DATASHEET: Nitrate vulnerable zone (NVZ) Eutrophic...

NVZ Name: Newtown Harbour, Medina Estuary, and Eastern Yar (Bembridge Harbour) NVZ ID: ET7

DATASHEET:

Nitrate vulnerable zone (NVZ) designation 2017 – Eutrophic Waters (Estuaries and Coastal Waters) Publication Date: June 2016

2 of 92

Introduction

This document provides a summary of the evidence used in proposing an area of land as one which

should be, or should continue to be, designated as a Nitrate Vulnerable Zone (NVZ) for the purposes

of the Nitrate Pollution Prevention Regulations 2015.

A full description of the methods used in developing the NVZ proposals is set out in the detailed

methodology for eutrophication-related NVZs, available via http://apps.environment-

agency.gov.uk/wiyby/141443.aspx. These methods were developed under the guidance of a review

group convened by the Defra for the last NVZ review (2011-2013), which included representatives

from the farming and water industries as well as independent academic experts. Minor refinements to

the methods have been made for the current review.

NVZs are areas of land that drain to polluted waters and which contribute to the pollution of those

waters. Polluted waters include those which are eutrophic or may in the near future become so if the

Regulations were not to apply there.

Eutrophication is defined as “the enrichment of water by nitrogen compounds, causing an accelerated

growth of algae and higher forms of plant life to produce an undesirable disturbance to the balance of

organisms present in the water and to the quality of the water concerned”.

For both freshwaters and saline waters, a weight-of-evidence based approach to assessing the risks

and impacts of eutrophication was employed. The evidence for individual water bodies was assessed

against a national suite of criteria for eutrophication in the different categories/ types of water for

review. The criteria are both quantitative and qualitative and reflect scientific understanding of the

process and effects of eutrophication. They are broken down in the same way for each water category

as follows:-

Nutrients

Plants/algae

Secondary and other effects

For each designated or candidate water body which might meet the criteria for eutrophication, a

datasheet such as this one was completed, bringing together information about the water body, its

catchment, its uses, evidence of eutrophication and the sources of nitrogen input.

This document is a record of the evidence used in the designation process, including results from

national monitoring and assessment programmes, and further information supplied by Area staff. The

proposals for NVZ designation are made as a result of close working between Area and national

Environment Agency teams, with further quality assurance for the eutrophication designations through

the use of a national expert panel.

Some features of the maps within this report are based on digital spatial data licensed from the

Centre for Ecology and Hydrology, ©.

Please note that any maps shown here have not used detailed field boundaries and therefore represent the indicative 'soft' boundary only. The definitive NVZ area can be seen on the “What’s in Your Backyard” (WIYBY) website ((http://apps.environment-agency.gov.uk/wiyby/141443.aspx).

The eutrophic water NVZ ID: ET7 was designated in 2005, and consists of the combined area draining to three estuaries on the Isle of Wight; Newtown Harbour, Medina Estuary, and Eastern Yar (Bembridge Harbour). There are individual datasheets relating to each Polluted Water (Eutrophic), but each has the same eutrophic water NVZ ID: ET7. A map of the combined NVZ is shown below. If you are appealing against the designation of land draining to one of the three estuaries, then please make sure you clearly reference which of the reports you are challenging.

http://apps.environment-agency.gov.uk/wiyby/141443.aspx

3 of 92

Report for existing Polluted Water Newtown Harbour

NVZ Name: Newtown Harbour NVZ ID: ET7

DATASHEET:

Nitrate vulnerable zone (NVZ) designation 2017 – Eutrophic Waters (Estuaries and Coastal Waters)

Publication Date: June 2016


Page 5

Introduction

This document provides a summary of the evidence used in proposing an area of land as one which should be, or should continue to be, designated as a Nitrate Vulnerable Zone (NVZ) for the purposes of the Nitrate Pollution Prevention Regulations 2015.

A full description of the methods used in developing the NVZ proposals is set out in the detailed methodology for eutrophication-related NVZs, available via http://apps.environment-agency.gov.uk/wiyby/141443.aspx . These methods were developed under the guidance of a review group convened by the Defra for the last NVZ review (2011-2013), which included representatives from the farming and water industries as well as independent academic experts. Minor refinements to the methods have been made for the current review.

NVZs are areas of land that drain to polluted waters and which contribute to the pollution of those waters. Polluted waters include those which are eutrophic or may in the near future become so if the Regulations were not to apply there.

Eutrophication is defined as “the enrichment of water by nitrogen compounds, causing an accelerated growth of algae and higher forms of plant life to produce an undesirable disturbance to the balance of organisms present in the water and to the quality of the water concerned”.

For both freshwaters and saline waters, a weight-of-evidence based approach to assessing the risks and impacts of eutrophication was employed. The evidence for individual water bodies was assessed against a national suite of criteria for eutrophication in the different categories/ types of water for review. The criteria are both quantitative and qualitative and reflect scientific understanding of the process and effects of eutrophication. They are broken down in the same way for each water category as follows:-

Nutrients Plants/algae Secondary and other effects

For each designated or candidate water body which might meet the criteria for eutrophication, a datasheet such as this one was completed, bringing together information about the water body, its catchment, its uses, evidence of eutrophication and the sources of nitrogen input.

This document is a record of the evidence used in the designation process, including results from national monitoring and assessment programmes, and further information supplied by Area staff. The proposals for NVZ designation are made as a result of close working between Area and national Environment Agency teams, with further quality assurance for the eutrophication designations through the use of a national expert panel.

Some features of the maps within this report are based on digital spatial data licensed from the Centre for Ecology and Hydrology, ©.







Form A (cover sheet) Page 6

Ref. Code: ET7

EC Urban Waste Water Treatment and Nitrates Directives

Use these forms for existing designations under:

Urban Waste Water Treatment Regulations: Sensitive Areas (Eutrophic); Sensitive Areas (Nitrate);

Nitrates Regulations: Polluted Waters (Eutrophic) leading to Nitrate Vulnerable Zone designation

Form A: Cover Sheet

Existing Sensitive Area (Eutrophic) and/or (Nitrate)/ Polluted Waters (Eutrophic)

Take information for questions 1 – 7 from original candidate reports (if available)

Sensitive Area coverage (highlight appropriate coverage):

England England &

Wales Wales

England & Scotland

1) Name of regulator

Environment Agency, Solent & South Downs Area

2) Designated Site name

Newtown Harbour

3) Main river catchment

There are several small inflowing streams, the main ones being the Caule Bourne and Rodge Brook

4) Location & extent of Designated Site

Whole harbour - see Figure 1

5) Type(s) of water body (Tick all boxes that apply)

Running freshwater

Still freshwater

Y Estuarine water

Coastal water



6) In previous reviews this site was designated as a: (Tick all that apply)

Y Sensitive Area (Eutrophic)

Y Polluted Water (Eutrophic)

Sensitive Area (Nitrate)

7) Summary of qualifying sewage treatment work (STW)

discharges (ie greater than p.e. 10,000) which contribute to the pollution of the sensitive area.

Candidate name: Newtown Harbour

Name of discharge

Direct / Indirect

NGR Population equivalent

Current Treatment

Planned Type of TER (N, P, NP)

Level (PRIM, SEC, TER)

if TER enter Type (N, P, NP)

Pennington STW Indirect SZ 3315 9187 52,671 TER N

Total PE 52,671

8) Executive summary of evidence of change in eutrophic status since designation:

Newtown Harbour has dual designation as both a Sensitive Area (Eutrophic) and a Polluted Water (Eutrophic). It was designated a Sensitive Area (Eutrophic) under the Urban Waste Water Treatment Directive (UWWTD) in 2007. There are no direct sewage treatment works (STW) discharges into Newtown Harbour but as a result of its designation, nutrient stripping was undertaken at an indirect qualifying sewage discharge to the Solent outside Newtown Harbour (Pennington STW). Newtown Harbour was designated a Polluted Water (Eutrophic) under the Nitrates Directive in 2008, with a Nitrate Vulnerable Zone (NVZ) established in its catchment. In addition the catchment forms part of the Solent Diffuse Water Pollution Plan which was set up to tackle diffuse nutrient sources in the Solent European Marine Sites.

At the time of the designations there was evidence that Newtown Harbour was eutrophic, based on the widespread growth of the opportunistic macroalgae Enteromorpha spp. and Ulva spp. Macroalgal surveys undertaken in 2001, 2002 and 2003 indicated that macroalgae (25 to 100% cover) covered 33 to 63 ha of the intertidal area, exceeding the ‘25% of the intertidal area’ UWWTD criteria in the 2001 survey.

This review focuses on nutrients and macroalgae because other potential indicators such as Dissolved Oxygen sags and phytoplankton blooms have never been an issue in Newtown Harbour (summary information is presented to confirm this).

Evidence from more recent studies show that Newtown Harbour remains hypernutrified with nitrogen concentrations exceeding the standards used to assess UWWTD compliance and producing a classification of Moderate under the Water Framework Directive (WFD). Similarly macroalgal cover remains high. Macroalgal surveys undertaken in 2008, 2012 and 2015 indicate that between 65 and 88 ha of intertidal area was covered in macroalgae. This represents between 45 and 61 % of the available intertidal area which



exceeds UWWTD criteria. Recent levels of cover are similar to pre-designation levels (2001), although there is significant inter-annual variation in extent over all the years monitored. The 2008 WFD macroalgae classification is Moderate, based on the combination of percentage cover, biomass, and small areas of entrained macroalgae (WFD classifications are not possible for the 2012 and 2015 surveys). Macroalgae in Newtown Harbour does not persist throughout the winter. Overall, there is clear evidence that there remains a eutrophication problem in Newtown Harbour.

The nutrient budget for Newtown Harbour shows that the biggest nitrogen contribution (about 40%) is from direct freshwater diffuse agricultural sources. Approximately 29% of nitrogen is from offshore coastal background sources and 27% is from indirect rivers and STW inputs via offshore. The remainder (<4%) is from direct STW inputs. The modelling supports the existing Polluted Water designation in that nitrogen from agricultural sources is a substantial contribution to the nitrogen inputs into Newtown Harbour.

Current measures to reduce nitrogen into Newtown Harbour from agricultural and sewage sources include a mixture of statutory and voluntary measures. Statutory measures include nutrient stripping at an offshore qualifying sewage works and mandatory agricultural practice rules in the NVZ known as the Action Programme Measures. Voluntary measures derive from advice and incentives to farmers and landowners and include Catchment Sensitive Farming projects, Environmental Stewardship Schemes and other measures detailed in the Solent Diffuse Water Pollution Plan.

Nutrient control measures should not be removed as the process of nutrient/ eutrophication reduction in Newtown Harbour will take a long time for a variety of reasons including the influence of groundwater (in which nitrogen will decline very slowly), the relatively recent and/or ongoing implementation of measures, the variety of sources, natural biological time lag and natural inter-annual variation.

A steady concerted effort to reduce different nutrient sources to Newtown Harbour is ongoing and this should not be interrupted or stopped.

On the basis of the evidence summarised in this document the NVZ should remain in place.

Now progress to the relevant form(s) for the Sensitive Area/Polluted Water

Form B – Running Freshwaters (information, data, evidence)

Form C – Still Freshwaters (information, data, evidence)

Form D – Estuarine (transitional) Waters (information, data, evidence)

Form E – Coastal Waters (information, data, evidence)

Form G – Actual effect of nutrient removal at qualifying discharge works


Form D (information, data, evidence) Page 9

Ref. Code: ET7


Form D: Estuarine Waters – Information, data, evidence

Existing Sensitive Area (Eutrophic) / Polluted Waters (Eutrophic)

1) Designated Site name: Newtown Harbour

2) Define approximate area of estuarine water using grid references:

The PW(E) designation covers the whole of Newtown Harbour (see Fig 1).

NGR 1: SZ 39966 89480 NGR 2: SZ 44766 89480

NGR 3: SZ 39966 92143 NGR 4: SZ 44766 92143

Surface area (ha): 210 ha

3) Attach map showing the SA(E)/PW(E), Water Framework Directive (WFD) waterbodies and locations of chemical sample points, biological sample points, any direct or indirect sewage treatment work discharges, direct or indirect discharges of nitrogen compounds from agricultural sources, and other significant discharges of nitrogen or phosphorus e.g. industrial.

See Figures 1 & 2

4) Approximate retention/flushing time (days): Approximately 2 days

5) Brief description of geo-morphological nature of estuary

Newtown Harbour (also known as Newtown River) is a small relatively sheltered, mixed, meso tidal estuary on the north coast of the Isle of Wight. It is a multi-armed estuary that receives input from a number of small freshwater streams, the main ones being the Caule Bourne and Rodge Brook. The only significant contribution from groundwater to Newtown Harbour is via the Caule Bourne: approximately 70% of baseflow in the Caule Bourne is from Central Chalk groundwater. The Central Chalk groundwater body is currently at poor status for groundwater quality due to rising trends in nitrate.

The area of the harbour below mean spring high water mark is approximately 2.1km2; the area below the mean spring low water mark is approximately 0.2km2. As a consequence most of the water in the harbour is replaced each tide.

Much of the estuary lies within a rural environment containing woodland and farm land. The land to the north east of the estuary is MOD land which is used for training exercises. The harbour has considerable amenity



value and is used for both bird watching and for recreational boating. The harbour and much of the surrounding land is owned by the National Trust. The harbour is a designated shellfish water.

Newtown Harbour is included within the Solent and Southampton Water SPA and the Solent Maritime SAC. It is also a Ramsar site and an SSSI.

6) Summary of main uses and designations: (Tick all boxes that apply)

Y Amenity Y Boating

Y Water sports Y OSPAR problem area

EC Bathing Water Angling

Commercial fishery Y Designated EC Shellfish Water

Y Designated EC Shellfish Harvesting Area

Non - designated shellfish harvesting area

Other uses or designations:

1. 2.

7) If waterbody has conservation status provide details

SOLENT MARITIME Special Area of Conservation (SAC)(EC Habitats Directive)

SOLENT & SOUTHAMPTON WATER Special Protection Area (SPA)(EC Birds Directive)

SOLENT AND SOUTHAMPTON WATER Ramsar (wetland of international importance designated under the Ramsar Convention)

NEWTOWN HARBOUR Site of Special Scientific Interest (Wildlife and Countryside Act 1981, as amended)

The site includes extensive areas of estuarine mudflats and saltmarsh that form a dendritic pattern of tidal creeks and large areas of intertidal mud at the Solent shore with beds of eel grass occurring locally. The estuary and peripheral land is a very important component of The Solent estuarine system which supports internationally important overwintering populations of wildfowl and waders, and important breeding populations of waders, gulls and terns.

The SPA and SAC comprise Protected Areas under the EC Water Framework Directive and Marine Protected Areas (MPA) under the EC Marine Strategy Framework Directive. Natural England advises that eutrophication, due to elevated nitrogen, is a recognised threat to the condition of these designated sites, particularly through increased macroalgal abundance. The reported MPA target is to restore water quality to mean winter dissolved inorganic nitrogen levels at which biological indicators of eutrophication (opportunistic macroalgal and phytoplankton blooms) do not affect the integrity of the site and features.

8) What chemical data are available? (Tick boxes if evidence is supplied)

Y Dissolved available inorganic phosphorus (DAIP)

Y Dissolved available inorganic nitrogen (DAIN)

Y Chlorophyll-a

Cell counts

Dissolved Oxygen



9) What biological / observational data are available?

(Tick boxes if evidence is supplied)

Angiosperms

Y Planktonic algal blooms

Y Macroalgae

Presence of foam / scum

Shellfish / invertebrate / fish mortality

Photographs



Figure 1 Map showing Newtown Harbour, extent of Water Framework Directive water body, Polluted Waters (Eutrophic), rivers and the location of the STW discharge which has had improvements under the UWWTD and Habitats Directive. The extent of the NVZ in the catchment is shown hatched in yellow.

Newtown

Harbour



Figure 2 Newtown Harbour showing water sampling points from both the marine and freshwater environment and biological sample points for seasonal macroalgae surveys.

Newtown

Harbour



Nutrients

Nutrients have been monitored at five monitoring points throughout Newtown Harbour. Table 1 below summarises DAIN (Dissolved Available Inorganic Nitrogen) and DAIP (Dissolved Available Inorganic Phosphorus) data to 2015 for each site in the estuary, showing annual average and winter average concentrations (where winter is November to February).

Table 1 Summary of Chemical data for Newtown Harbour

Annual Average

Data Start Year

Count (DAIN)

Chlorophyll (ug/l)

DAIN (mmol/m3)

DAIN (mg/l)

DAIP (mmol/m3)

DAIP (mg/l) Salinity

Y0004445

NEWTOWN HARBOUR - SLIPWAY AT SHALFLEET QUAY 2004 83 3.25 70.25 0.984 1.01 0.031 27.07

Y0004446

NEWTOWN TOWN COPSE(FORMERLY QUAY NORTH TAYLORS COPSE) 2004 75 3.99 19.31 0.270 0.568 0.018 31.73

G0006461 NEWTOWN HARBOUR OFF NEWTOWN QUAY 2012 8 26.86 0.376 0.775 0.024 33.22

G0006460 NEWTOWN HARBOUR, CLAMERKIN LAKE 2012 8 26.92 0.377 0.694 0.022 32.95

Y0017476

NEWTOWN HARBOUR-SHELLFISH WATER, 50'43.350N, 01'24.500W 1999 117 13.37 0.187 0.499 0.015 33.55

Winter Average

Data Start Year

Count (DAIN)

Chlorophyll (ug/l)

DAIN (mmol/m3)

DAIN (mg/l)

DAIP (mmol/m3)


Y0004445

NEWTOWN HARBOUR - SLIPWAY AT SHALFLEET QUAY 2004 23 116.45 1.63 1.26 0.039 25.09

Y0004446

NEWTOWN TOWN COPSE(FORMERLY QUAY

NORTH TAYLORS COPSE) 2004 22 42.82 0.600 0.677 0.021 29.27

G0006461 NEWTOWN HARBOUR OFF NEWTOWN QUAY 2012 8 26.86 0.376 0.775 0.024 33.22

G0006460 NEWTOWN HARBOUR, CLAMERKIN LAKE 2012 8 26.92 0.377 0.694 0.022 32.95

Y0017476

NEWTOWN HARBOUR-SHELLFISH WATER, 50'43.350N, 01'24.500W 1999 40 24.42 0.342 0.729 0.023 33.22

Note: Newtown Harbour has been shown by previous work to be nitrogen limited, so nitrogen is the key nutrient of concern for macroalgal growth. In this report nitrogen is also referred to as DAIN and DIN (Dissolved Inorganic Nitrogen) because this is the terminology used for nitrogen standards that relate to relevant EU Directives. Since Newtown Harbour is nitrogen limited, phosphorus data is only shown initially to enable comparison with nutrient standards.

The data in Table 1 show that in all sampling locations nutrients exceed the CSTT* standards that were used to assess UWWTD compliance: these standards state that ‘hypernutrification exists when winter values of nutrient concentrations significantly exceed 12mmoles/m³ DAIN in the presence of at least 0.2mmoles/m³ DAIP’. The relevant data are shown in red in Table 1.

*CSTT = Comprehensive Studies Task Team



Similarly, annual Water Framework (WFD) classifications from 2009 to 2015 in Newtown Harbour show that DIN is consistently Moderate (ie less than Good).

Seasonal variation in nutrients

Seasonal averages are shown in Figure 3. Winter salinities are lower than summer salinities indicating that freshwater inputs are a greater influence in the winter months, especially at sites nearest the freshwater stream inputs. Winter DAIN concentrations are higher than summer concentrations, especially at sites which are influenced by the freshwater nutrient inputs.

Figure 3 Winter and summer average DAIN in Newtown Harbour from 1999 to 2015 (where where winter is November to February and summer is April to September). Site Y0004445 is nearest the Caule Bourne stream and site Y0017476 is nearest the harbour mouth.



Late winter nutrients give the best estimate of nutrients that will be available in spring to support primary production. Mid summer nutrient concentrations demonstrate if nutrients limit primary production in the summer.

Spatial variation in nutrients

Figure 4 shows a scatter plot of winter DAIN against salinity at all sites, confirming the general relationship between elevated nitrogen and low salinity (fresh water).

Figure 4 Scatter plot of winter DAIN vs salinity at all sites, data from 1999 to 2015 (where where winter is November to February).

Figure 5 shows the winter DAIN data spatially on a map of Newtown Harbour. This shows that winter nutrient concentrations are lowest near the estuary mouth and within the main body of the estuary. They are higher in the arms of estuary where the streams enter, reflecting the importance of riverine nutrient loads locally.



Figure 5 Average winter DAIN concentrations in Newtown Harbour and the Rivers Caule Bourne and Rodge Brook (1999 to 2015)

Trends in riverine nutrients

DAIN data from sampling points in the two main freshwater streams (Caule Bourne and Rodge Brook) suggests that DAIN levels in the rivers have not changed much over the last 25 years and 14 years respectively.



Figures 6 & 7: Trends in riverine DAIN at lowest sampling points in the Caule Bourne (1990 to 2015) and Rodge Brook (1990 to 2004)



0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

DA

IN (m

g/l)

Y0017476 - Newtown Harbour Shellfish Water

0.00

1.00

2.00

3.00

4.00

5.00

6.00

DA

IN (m

g/l)

Y0004445 - Shalfleet Quay Slipway

Trends in nutrients in Newtown Harbour

Similarly, nitrogen levels in the Newtown Harbour have not much changed over the last decade (no earlier data is available) as shown in Figures 8 and 9.

Figures 8 & 9 DAIN concentrations in the estuary mouth and upper estuary to 2015

(Please note different scales for DAIN on the two graphs)

Site Y0017476 nearest the harbour mouth, 2002-2015

Site Y0004445 is nearest the Caule Bourne, 2004-2015



Graphs for the other 3 sites in Newtown Harbour are shown in Appendix 1.

The estuarine DAIN data have been analysed prior to and following the NVZ designation in 2008, to see if there is any evidence of decreased nutrients following the designation. Table 2 shows the data prior to NVZ designation (up to 2007) and following NVZ designation (2009 to present). There are only three sites where both pre and post designation data is available. Figure 10 presents the winter pre & post NVZ designation data spatially on a map of the harbour.

Table 2 Winter DAIN data pre & post NVZ designation in 2008

Winter Average

DAIN (mg/l) Winter Average DAIN (mmol/m3)

1994-2007

2009-2015

1994-2007

2009-2015

Y0004445*

NEWTOWN HARBOUR - SLIPWAY AT SHALFLEET

QUAY* 0.985 2.242 70.3 160.0

Y0004446 NEWTOWN TOWN COPSE (FORMERLY QUAY NORTH TAYLORS COPSE)* 0.503 0.692 35.9 49.4

G0006461 NEWTOWN HARBOUR OFF NEWTOWN QUAY

0.376

26.862

G0006460 NEWTOWN HARBOUR, CLAMERKIN LAKE

0.377

26.916

Y0017476 NEWTOWN HARBOUR-SHELLFISH WATER, 50'43.350N, 01'24.500W 0.393 0.314 28.0 22.4

* Data set starts in 2004

Data in red shows it exceeds the CSTT winter DAIN standard of 12 mmol/m³



Figure 10 Mean winter DAIN concentration before and after NVZ designation in 2008

The data shows no clear trend of a reduction of N in the estuary in the 7 years following NVZ designation in 2008. Indeed at the two sites nearest the freshwater streams, DAIN appears to have increased; however there is insufficient data to support a detailed analysis. The data shows that Newtown Harbour remains subject to elevated nutrients in the period following designation as an NVZ. (There is insufficient data following recent nutrient stripping at STW discharges in 2014 to assess any changes from this).

In summary, all the data confirms that Newtown Harbour remains hypernutrified (high in nutrients) throughout the period. There are no clear signs of a reduction in nutrients in either the rivers or the estuary.

Chlorophyll data and planktonic algal blooms

Newtown Harbour does not exhibit high chlorophyll concentrations or significant phytoplankton blooms. Its status as an SA(E) and PW(E) relates only to macroalgal growth.

Recent WFD phytoplankton data confirms that Newtown Harbour is of consistently HIGH status for Phytoplankton, demonstrating that phytoplankton blooms are not of concern. The tool on which this classification is based includes an analysis of chlorophyll concentrations. Chlorophyll concentrations from 2009 to 2015 are consistently within the chlorophyll standard.

The annual average chlorophyll concentrations shown in Table 1 demonstrate the low chlorophyll concentrations found in Newtown Harbour.

Macroalgae

Previous studies of macroalgae within Newtown Harbour in the 2000’s reached the conclusion that Newtown Harbour should be designated as a Sensitive Area in 2007. Macroalgae surveys with aerial photography taken in 2001, 2002 and 2003 concluded that macroalgae (25 to 100% cover) covered 33 to 63 ha of the intertidal area, exceeding the ‘25% of the intertidal area’ UWWTD criteria in the 2001 survey. This review



resulted in the recommendation of consent conditions for nitrogen stripping at the qualifying sewage discharge from Pennington. This was delivered in 2014.

In the 2005 Habitats directive review, the quantity of macroalgae in Newtown Harbour was considered to contribute to adverse effect on site integrity in Solent and Southampton Water SPA (of which Newtown Harbour is part). This resulted in the recommendation of more stringent consent conditions for nitrogen stripping at Pennington and this improvement was delivered in 2015.

More recently macroalgae in Newtown Harbour has been assessed under the WFD. The WFD classification method uses data on percent cover, biomass and the presence of entrained algae. Macroalgae surveys in Newtown Harbour were undertaken in 2008, 2012 and 2015 using remote sensing methods based on aerial imagery. Interpretation of the aerial images concluded that between 65 to 88 ha of intertidal area was covered in macroalgae. This represents between 45 and 61 % of the available intertidal area which exceeds UWWTD criteria.

The WFD survey from 2008 indicates that Newtown Harbour would only achieve Moderate status for macroalgae under WFD (EQR* score of 0.49). Unfortunately no classification is available for the 2012 and 2015 surveys because the surveys could not be fully completed (as no hovercraft access was allowed to enable the collection of biomass samples). No significant amounts of entrained macroalgae were present in the 2008 WFD survey.

* The WFD classification is reported as an Ecological Quality Ratio (EQR). The EQR value ranges from 0 to 1. An EQR with a value of 1 represents reference conditions and a value of 0 represents a severe impact.

Trends in macroalgae

Figure 11 shows the variability in the extent of macroalgae in Newtown Harbour during the different surveys. The least macroalgal cover was recorded in the summers of 2002 and 2003 with approximately 33 ha recorded; the highest macroalgal cover was recorded in 2008 at 88 ha. These changes are likely to represent natural inter-annual variability; there is little evidence of a temporal trend in macroalgal cover. Further macroalgal monitoring in future is recommended given the high inter-annual variability at Newtown.

Figure 11 Extent of macroalgae in Newtown Harbour (Summer 2001 to 2015)

0

10

20

30

40

50

60

70

80

90

100

2001 2002 2003 2008 2012 2015

Are

a (H

a)

Year

Newtown - Extent of macrolage (greater than 15% cover)



Seasonal macroalgal biomass surveys

Two sites in Newtown Harbour have been monitored for seasonal changes in macroalgae. Macroalgal biomass was measured every two months to assess how macroalgae varies throughout the year and whether it persists over winter. The sites at Shalfleet and Causeway Lake (see Figure 2) have been regularly monitored between March 2003 and May 2006. The results are shown in Figure 12.

Figure 12 Macroalgal seasonal biomass at Shalfleet and Causeway Lake in Newtown Harbour

0

500

1000

1500

2000

2500

3000

3500

4000

Ma

r-03

Ma

y-0

3

Ju

l-0

3

Sep

-03

Nov-0

3

Ja

n-0

4

Ma

r-04

Ma

y-0

4

Ju

l-0

4

Sep

-04

Nov-0

4

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5

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r-05

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5

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5

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-05

Nov-0

5

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6

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r-06

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6

We

t w

eig

ht

[g m

2]

Newtown - Shalfleet Mean Newtown - Causeway Lake Mean

The results show that peak biomass (up to 3.6 kg/m2) occurs between May and November. Macroalgae does not survive the winter months of January to March – biomass declines to nil. However some macroalgae persisted in Shalfleet creek in January 2005 but did not survive into March 2005.

Overall, the macroalgae evidence clearly indicates that macroalgae is still a problem in Newtown Harbour based on the combination of extent, percentage cover and biomass. However, there is no significant entrained macroalgae and macroalgae does not persist over winter.

10) Which of the methodology indicators are exceeded?

Y Nitrate concentrations (February nitrogen concentrations significantly enhanced)

WFD phytoplankton classification of moderate ecological status or worse

Occurrence of unusual algal blooms

Oxygen deficiency (based on WFD and/or UWWT/Nitrate directive methods )

Y Macroalgae exceeds thresholds (UWWT and WFD)



11) Other evidence of adverse effects on uses and designations:

If overwintering macroalgae is present at the same time as important overwintering birds (for which the site is designated under the Habitats Directive), the macroalgae may interfere with feeding patterns and prey distribution. However macroalgae is not present in the winter months in Newtown Harbour.

If present, entrained macroalgae and overwintering macroalgae reduces the time and opportunity for the mudflats to recover from its adverse effects. However there is no significant entrained macroalgae or overwintering macroalgae in Newtown Harbour.



12) List the current WFD status/potential for any WFD waterbodies within the SA(E)/PW(E)

Waterbody ID Waterbody Name

Current overall status

2015

Ecological status

2015

Status of biological elements sensitive to nutrient enrichment 2015

Status of Phys-chem supporting elements 2015

Phytoplankton Macroalgae Angiosperms Disolved Inorganic Nitrogen

Dissolved Oxygen

GB520710101700 NEWTOWN RIVER

(Transitional water

body)

Moderate Moderate High Moderate Moderate High

Based on the Environment Agency’s latest (December 2015) weight-of-evidence assessment for certainty of eutrophication, this estuary currently comes out as “Very Certain of a eutrophication problem”. Further details of the weight-of-evidence approach are set out in the method statement for waters subject to eutrophication (Defra, 2016).

13) Is/are the WFD waterbody catchment/s in the SA(E)/PW(E) failing or at risk of failing the dissolved inorganic nitrogen standard for WFD?

Newtown River transitional waterbody is failing the DIN standard for WFD (Moderate status). .

There is a groundwater contribution to Newtown Harbour from baseflow in the Caule Bourne. The Central Chalk groundwater body is currently at Poor status for groundwater quality due to rising trends in nitrate. It failed the Drinking Water Protected Area test for nitrate.



14) Executive summary of the chemical, biological and other evidence illustrating eutrophication in the SA(E)/PW(E)

DIN is classified as Moderate under the WFD and winter DAIN exceeds standards used to assess UWWTD compliance, indicating that Newtown Harbour is hypernutrified throughout. Average levels of DAIN in the two main inflowing streams have remained similar over the period monitored (up to 25 years).

The primary symptom of eutrophication in Newtown Harbour is the development of extensive mats of green macroalgae, primarily Enteromorpha spp. and Ulva spp., in intertidal areas throughout the harbour. Macroalgae in Newtown Harbour is classified as Moderate status under the WFD. Macroalgae surveys in 2008, 2012 and 2015 indicate that macroalgae cover between 45 and 61 % of the available intertidal area, which exceeds UWWTD criteria. Levels of macroalgal cover in 2012 and 2015 were similar to levels in 2001 (pre-designation). Further macroalgae monitoring is recommended particularly as there is significant inter annual variability in macroalgal growth. The summer biomass of macroalgae generally exceeds 1000g/m2 in sheltered sites (eg the bi-monthly monitoring sites). However there is no significant entrained macroalgae and macroalgae does not persists throughout the winter.

There is therefore clear evidence that there remains a eutrophication problem in Newtown Harbour.

15) Summary of eutrophication control measures (already in progress and/or already planned) if any, for

the existing area.

Statutory measures

Newtown Harbour was designated an SA(E) in 2007. As a result nitrogen stripping to 15 mg/l was installed by 2014 at Pennington indirect STW. This standard was further tightened as a result of the Habitats Directive Review of Consents, to 9.5 mg/l by 2015.

Newtown Harbour was designated a PW(E) in 2008 and the catchment draining to it was designated an NVZ (see Figure 1). This means that specific farming practices are controlled in the designated area to reduce nitrogen losses from agriculture to water. The NVZ designation:

Requires farmers within the NVZ to reduce nitrate pollution.

The farmers must follow a set of mandatory rules, known as the Action Programme Measures.

The Action Programme Measures are based on Good Agricultural practice and require the careful management and recording of fertiliser and manure use.

Voluntary measures

There are additional also voluntary measures in place within the catchment draining to Newtown Harbour. These measures derive from advice and incentives to farmers and landowners to reduce nutrient inputs to water, and include:

Catchment Sensitive Farming (CSF) projects

Environmental Stewardship Schemes

Solent Diffuse Water Pollution Plan which relates to several catchments that border the Eastern Solent and the Isle of Wight


Form G (Effects of Nutrient Reduction) Page 27

Ref. Code: ET7


Form G: Effects of Nutrient Reduction


1) Designated Site name: Newtown Harbour (take name from Form A)

2) Type(s) of water body: (take info from Form A)

Running freshwater

Still freshwater

Y Estuarine water

Coastal water

3) Summary of qualifying sewage treatment work discharges (copy info from Form A)

Candidate name: Newtown Harbour

Name of qualifying discharge

Direct/Indirect

NGR Population Equivalent

Current level of treatment

(>10,000 PE)

Pennington

STW Indirect SZ 3315 9187 52,671 TERTIARY

Total PE 52,671

Remarks:

Note: Newtown Harbour also receives sewage effluent from other STWs as follows, but these works are too small, or contribute too little, to qualify under the UWWTD; but they were including in all modelling work as discussed in section 5 below:

STWs in the freshwater Caule Bourne stream (Shalfleet and Bourne STWs)

Large marine STWs discharging outside the harbour into the Solent (with water exchange at the harbour entrance)

The locations of these other STW sources are shown in the map in Appendix 2.

4) Summarise the comparative impact of the discharges (e.g.compare chemical and biological data upstream and downstream of the sewage discharge) in relation to pre-designation.


Form G (effects of nutrient reduction) Page 28

N/A

5) Where available provide estimates of nutrient loading for contributions for both qualifying sewage treatment work discharges and agricultural sources. Summarise how this has changed over time

Annual nitrogen contributions to Newtown Harbour were calculated for WFD nutrient investigations. The contributions were calculated taking into account the nutrient reductions at Pennington STW. They are shown in Figure 13 (which is colour coded to show contributions from marine sources in blue, river sources in greens and sewage sources in reds).

Figure 13 Relative contributions of all nitrogen sources within Newtown Harbour

Other Streams Diffuse = 27%

Caulebourne Diffuse = 13.5%

Caulebourne STW (Shalfleet) = 3.5%

Offshore Coastal background = 29%

Offshore Christchurch Rivers = 12%

Offshore River Test = 4%

Offshore River Itchen = 2% Offshore other (<1% each) =

9%

Sources of nitrogen into Newtown Harbour

Other Streams Diffuse = 27%

Caulebourne Diffuse = 13.5%

Caulebourne STW (Shalfleet) = 3.5%



Offshore River Test = 4%

Offshore River Itchen = 2%

Offshore other (<1% each) = 9%

Notes:

The map in Appendix 2 should be viewed in association with this source apportionment information as it shows the locations of the rivers and point sources refered to.

The data is derived from model outputs from CPM, SAGIS and Telemac models.

These figures confirm that over a third of nitrogen in the Newtown Harbour (about 40%) is from direct freshwater diffuse agricultural sources: from the Caule Bourne (13.5%) and other local streams (27%). About 29% is from offshore coastal background sources and 27% is from indirect rivers and STW inputs via offshore. The remainder (<4%) is from two STW inputs into the freshwater Caule Bourne (Shalfleet STW and Bourne STW).

The figures support the Polluted Water designation as the biggest nitrogen contribution (about 40%) is from agricultural sources in the Newtown catchment.

Summarise how this has changed over time.

DAIN concentrations over time in the Caule Bourne and Rodge Brook are shown in Figure 14. The graphs do not show any clear trends in DAIN over the time periods for which data is available (25 years and 14 years respectively). There is no evidence of a decrease in nitrogen in the Caule Bourne



stream following the NVZ designation in 2008 (the Rodge Brook data set finishes prior to the NVZ designation). This may be partly because of the influence of groundwater in the catchment: nitrate in groundwater takes for a long time to travel to the water table so consequently it will take years to see the results of measures to reduce nitrate loading in the catchment.

Figure 14 Trends in annual average DAIN in the Caule Bourne (1990 to 2015) and Rodge Brook (1990 to 2004)

2008





Nitrogen concentrations from Pennington indirect STW discharge in the Solent are shown in Figure 15. Nitrogen reduction at this STW was only implemented very recently (2014/2015) and a consequent significant reduction in DAIN in the final effluent is evident from the graph. (Note: there is no data from 2010 to 2013).

Figure 15 Annual average concentration of DAIN in final effluent from Pennington STW 1995-2015. (This STW discharges outside Newtown Harbour and is large enough to qualify under the UWWTD).

6) Give a summary of the eutrophication control measures (in progress and/or planned), for the SA(E)/PW(E).

Statutory measures

Newtown Harbour was designated an SA(E) in 2007. As a result nitrogen stripping to 15 mg/l was installed by 2014 at Pennington indirect STW. This standard was further tightened as a result of the Habitats Directive Review of Consents, to 9.5 mg/l by 2015.

Newtown Harbour was designated a PW(E) in 2008 and the catchment draining to it was designated an NVZ (see Figure 1). This means that specific farming practices are controlled in the designated area to reduce nitrogen losses from agriculture to water. The NVZ designation:




Voluntary measures

There are additional also voluntary measures in place within the catchment draining to Newtown Harbour. These measures derive from advice and incentives to farmers and landowners to reduce nutrient inputs to water, and include:






7) If the SA(E)/PW(E) has previously been designated, is there any evidence to suggest that its status has changed (e.g. it is no longer eutrophic) and is this change a result of the control measures put in place, or due to a change in our methods/criteria, since the original designation?

There is no evidence that the eutrophication status of Newtown Harbour has changed – it is still eutrophic as shown by all the evidence above.

The coastal background source is a large nutrient source to Newtown Harbour and this is anticipated to reduce very slowly over time, reflecting improvements in agricultural diffuse and sewage sources throughout the Solent area. Sewage discharges are a relatively small nutrient source and many of the larger sewage discharges have already been tackled via nutrient stripping and STW diversion schemes. Agricultural diffuse sources are the biggest nutrient source and further reductions from this sector are anticipated as the uptake of statutory and regulatory measures continues.

Any changes are likely to take a long time for reasons including:

nutrients will take a long time to decrease in groundwater

STW improvements were relatively recently delivered

uptake of some agricultural measures is ongoing

the changes in nutrient loadings are relatively are small

there are a variety of nutrient sources

there is a natural biological time lag

there is inter-annual variation in natural factors like the weather

8) If control measures were removed, would the area be at risk of becoming eutrophic once more?

Nutrient control measures should not be removed as the process of nutrient reduction in Newtown Harbour will take a long time as outlined above. A steady concerted effort to reduce different nutrient sources to the harbour is ongoing and this should not be interrupted or stopped.

If nutrient control measures were removed Newtown Harbour might never change its status as a eutrophic water body.


Appendices Page 33

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IN (m

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G0006460

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G0006461

Appendix 1

Graphs of DAIN concentrations in the rest of Newtown Harbour to 2015

Site G0006460 Newtown Harbour Clamerkin Lake (2012-2015)

Site G0006461 Newtown Harbour Off Newtown Quay (2012-2015)


Appendices Page 34

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Y0004446

Site Y0004446 Newtown Town Copse, 2004-2015


Appendices Page 35

Appendix 2

Locations of the rivers and sewage treatment works (STWs) used in the modelling to calculate the contribution of nitrogen from each source into the harbours in the Solent area. Please note that all the small STWs in each of the freshwater catchments are included in the model, but may have not been included on this map.


NVZ Name: Medina Estuary NVZ ID: ET7

DATASHEET:



Report for existing Polluted Water Medina Estuary

Page 37

Introduction

















Ref. Code: ET7




Nitrates Regulations: Polluted Waters (Eutrophic) leading to Nitrate Vulnerable Zone designation

Form A: Cover Sheet




England England &

Wales Wales

England & Scotland




Medina Estuary


River Medina


Whole estuary - see Figure 1


Running freshwater

Still freshwater

Y Estuarine water

Coastal water




Y Sensitive Area (Eutrophic)





Candidate name: Medina Estuary

Name of discharge

Direct / Indirect


Current Treatment




Fairlee STW Direct SZ 3315 9187 -

Was diverted to Sandown STW in

2010. Sandown STW is distant

(discharges offshore) and has no

impact on the Medina.

Peel Common STW Indirect SZ5780097800 246,851 TER N

Total PE 246,851


The Medina Estuary has dual designation as both a Sensitive Area (Eutrophic) and Polluted Water (Eutrophic). It was designated a Sensitive Area (Eutrophic) in 2007 under the Urban Waste Water Treatment Directive (UWWTD). At that time there was one direct qualifying STW discharge into the estuary from Fairlee STW and one indirect qualifying STW discharge to the Solent, outside the Medina, from Peel Common STW. Fairlee STW was diverted to an offshore location (Sandown long sea outfall) in 2010 and nutrient stripping was undertaken at Peel Common STW in 2008. Further reductions in nitrogen from Habitats Directive requirements were delivered at Peel Common STW in 2015. The Medina Estuary was designated a Polluted Water (Eutrophic) under the Nitrates Directive in 2008, with an NVZ established in its catchment.

At the time of the designations there was clear evidence that the Medina Estuary was eutrophic, based on the widespread growth of the opportunistic macroalgae Enteromorpha spp. and Ulva spp. Macroalgal surveys undertaken in 2002 and 2003 indicated that macroalgae (25 to 100% cover) covered 42 to 50 ha of the intertidal area, exceeding the ‘25% of the intertidal area’ UWWTD criteria in both surveys.

This review focuses on nutrients and macroalgae because other potential indicators such as dissolved oxygen sags and phytoplankton blooms have never been an issue in the Medina Estuary (summary information is presented to confirm this).



Evidence from more recent studies show that the Medina Estuary remains hypernutrified with nitrogen concentrations exceeding the standards used to assess UWWTD compliance and producing a classification of Moderate under the Water Framework Directive (WFD). Similarly macroalgal cover remains high. Macroalgal surveys undertaken in 2008, 2012 and 2015 indicate that between 16 and 44ha of intertidal area was covered in macroalgae. This represents between 20 and 55 % of the available intertidal area which exceeds UWWTD criteria in 2012 and 2015. There is significant inter-annual variation in extent over the years monitored. Taken together, the 2008 and 2012 WFD macroalgae surveys indicate that the Medina would only achieve Moderate status for macroalgae under WFD, based on the combination of percentage cover, biomass, and small areas of entrained macroalgae. Macroalgae in the Medina Estuary does not persist throughout the winter. Overall, there is clear evidence that there remains a eutrophication problem in the Medina Estuary.

The nutrient budget for the Medina shows that the biggest nitrogen contribution (about 68%) is from direct freshwater diffuse agricultural sources. Approximately 12% of nitrogen is from offshore coastal background sources and 11% is from indirect rivers and STW inputs via offshore. The remaining 9% is from freshwater STW, urban and intermittent inputs. The modelling supports the existing Polluted Water designation in that nitrogen from agricultural sources is a large contribution to the nitrogen inputs into the Medina Estuary.

Current measures to reduce nitrogen into the Medina Estuary from agricultural and sewage sources include a mixture of statutory and voluntary measures. Statutory measures include nutrient stripping at an offshore qualifying sewage works and mandatory agricultural practice rules in the NVZ known as the Action Programme Measures. Voluntary measures derive from advice and incentives to farmers and landowners and include Catchment Sensitive Farming projects, Environmental Stewardship Schemes and other measures detailed in the Solent Diffuse Water Pollution Plan.

Nutrient control measures should not be removed as the process of nutrient/ eutrophication reduction in the Medina Estuary will take a long time for a variety of reasons including the influence of groundwater (in which nitrogen will decline very slowly), the relatively recent and/or ongoing implementation of measures, the variety of sources, natural biological time lag and natural inter-annual variation.

A steady concerted effort to reduce different nutrient sources to the Medina Estuary is ongoing and this should not be interrupted or stopped.










Ref. Code: ET7




1) Designated Site name: Medina Estuary


The PW(E) designation covers the whole of the Medina Estuary (see Fig 1).

Start point Newport Docks NGR 1: 450100 89400

End point East Cowes breakwater to West Cowes slipway NGR 3: 450040 96360 NGR 4: 449600 96360

Surface area (ha): 160 ha


See Figures 1 & 2

4) Approximate retention/flushing time (days): A few days


The Medina is a mixed, meso tidal estuary on the north coast of the Isle of Wight. It is a narrow estuary that extends 7 km from its tidal limit at Newport to the Solent at Cowes. It is fed at Newport by its main river, the River Medina with a smaller river, the Lukely Brook also joining from the west at Newport. The River Medina has approximately twice the flow of the Lukely Brook.

The Medina Estuary comprises a single subtidal channel, the deepest part of which is less than 3 m below chart datum. The low water channel is fairly straight and narrow and dries in much of its southern half. In the middle sections it widens with significant intertidal areas before narrowing to little more than 100 m in the middle of Cowes where both banks are built up. There are approximately 79 hectares of available intertidal habitat.

There is significant groundwater contribution to the estuary. The majority of the groundwater comes from the Lower Greensand aquifer which is not failing for nitrate (some denitrification occurs naturally in this groundwater body due to the groundwater chemistry). There also is some chalk groundwater contribution



from the Lukely Brook and the Central Chalk groundwater body which feeds into the lower reaches of the River Medina. The Central Chalk is currently at poor status for groundwater quality due to rising trends in nitrate. The Medina Estuary is included within the Solent and Southampton Water SPA and the Solent Maritime SAC. It is a Ramsar site and an SSSI.

The Medina Estuary is a centre for leisure sailing, particularly around Cowes. It is a designated shellfish water.


Y Amenity Y Boating


EC Bathing Water Y Angling

Y Commercial fishery Y Designated EC Shellfish Water

Y Designated EC Shellfish Harvesting Area



1. 2.


SOLENT MARITIME Special Area of Conservation (SAC)(EC Habitats Directive)



MEDINA ESTUARY Site of Special Scientific Interest (Wildlife and Countryside Act 1981, as amended)

The Medina Estuary comprises a tidal channel flanked by intertidal mudflats and saltmarsh in close association with a variety of brackish, freshwater and terrestrial habitats. The Medina is an important component of the wider Solent estuarine system which supports internationally important over-wintering migratory populations of wildfowl and wading birds, and importance breeding populations of waders, gulls and terns.

The SPA and SAC comprise Protected Areas under the EC Water Framework Directive and Marine Protected Areas (MPA) under the EC Marine Strategy Framework Directive. Natural England advises that eutrophication, due to elevated nitrogen, is a recognised threat to the condition of the Medina Estuary, particularly through increased macroalgal abundance. The reported MPA target is to restore water quality to mean winter dissolved inorganic nitrogen levels at which biological indicators of eutrophication (opportunistic macroalgal and phytoplankton blooms) do not affect the integrity of the site and features.

8) What chemical data are available? (Tick boxes if evidence is supplied)



Y Chlorophyll-a

Cell counts

Dissolved Oxygen




(Tick boxes if evidence is supplied)

Angiosperms


Y Macroalgae



Photographs



Figure 1 Map showing the Medina Estuary, extent of Water Framework Directive water body, Polluted Waters (Eutrophic), rivers and the location of the STW discharges which have been diverted or had improvements under the UWWTD and Habitats Directive. The extent of the NVZ in the catchment is shown hatched in yellow.

Medina Estuary



Figure 2 The Medina Estuary showing water sampling points from both the marine and freshwater environment and biological sample points for seasonal macroalgae surveys.

Medina Estuary



Nutrients

Nutrients have been monitored at six monitoring points throughout the Medina Estuary. Table 1 below summarises DAIN (Dissolved Available Inorganic Nitrogen) and DAIP (Dissolved Available Inorganic Phosphorus) data to 2015 for each site in the estuary, showing annual average and winter average concentrations (where winter is November to February).

Table 1 Summary of Chemical data for the Medina Estuary

Annual Average

Data Start Year

Count (DAIN)

Chlorophyll (ug/l)

DAIN (mmol/m3)

DAIN (mg/l)

DAIP (mmol/m3)


Y0004369 MEDINA NEWPORT DOCKS 1992 161 9.23 314.5 4.41 2.00 0.062 10.5

Y0004366 MEDINA VALLEY CENTRE 2011 9 186.1 2.61 1.07 0.033 23.3

Y0004361 MEDINA ESTUARY AT FOLLY INN 1990 222 4.90 55.0 0.77 1.92 0.060 30.3

Y0004385 MEDINA-SHELLFISH WATER 2010 48 2.49 29.1 0.41 0.70 0.022 32.3

Y0004438

MEDINA SHELLFISH - CEFAS BED REF - B063B 2011 9 35.3 0.49 0.84 0.026 32.4

Y0004356

MEDINA ESTUARY, WEST COWES-*CLOSED* 1992 141 2.30 25.7 0.36 0.94 0.029 32.5

Winter Average

Data Start Year

Count (DAIN)

Chlorophyll (ug/l)

DAIN (mmol/m3)

DAIN (mg/l)

DAIP (mmol/m3)


Y0004369 MEDINA NEWPORT DOCKS 1992 58 3.48 362.4 5.08 1.82 0.056 9.9

Y0004366 MEDINA VALLEY CENTRE 2011 9 186.1 2.61 1.07 0.033 23.3

Y0004361 MEDINA ESTUARY AT FOLLY INN 1990 72 3.42 78.5 1.10 2.09 0.065 28.7

Y0004385 MEDINA-SHELLFISH WATER

2010 22 2.25 45.8 0.64 0.96 0.030 31.0

Y0004438

MEDINA SHELLFISH - CEFAS BED REF - B063B 2011 9 35.3 0.49 0.84 0.026 32.4

Y0004356

MEDINA ESTUARY, WEST COWES-*CLOSED* 1992 45 1.32 38.7 0.54 1.27 0.039 32.0

Note: In this report nitrogen is also referred to as DAIN and DIN (Dissolved Inorganic Nitrogen) because this is the terminology used for nitrogen standards that relate to relevant EU Directives. Phosphorus data is only shown initially to enable comparison with nutrient standards.

The data in Table 1 show that in all sampling locations nutrients exceed the CSTT* standards that were used to assess UWWTD compliance: these standards state that ‘hypernutrification exists when winter values of nutrient concentrations significantly exceed 12mmoles/m³ DAIN in the presence of at least 0.2mmoles/m³ DAIP’. The relevant data are shown in red in Table 1.




Similarly, annual Water Framework (WFD) classifications from 2009 to 2015 in the Medina show that DIN is consistently Moderate (ie less than Good).


Seasonal averages are shown in Figure 3. Winter salinities are lower than summer salinities indicating that freshwater inputs are a greater influence in the winter months, although salinities are very similar at the top and bottom sites. Winter DAIN concentrations are higher than summer concentrations, especially at sites which are influenced by the freshwater nutrient inputs.

Figure 3 Winter and summer average DAIN in the Medina Estuary from 1990 to 2015 (where winter is November to February and summer is April to September). The top site Y0004369 is nearest the River Medina and the bottom site Y0004356 is nearest the estuary mouth.

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IN (m

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Seasonal Averages

DAIN Summer Mean

DAIN Winter Mean

Salinity Summer Mean

Salinity Winter Mean

River >-

Late winter nutrients give the best estimate of nutrients that will be available in spring to support primary production. Mid summer nutrient concentrations demonstrate if nutrients limit primary production in the summer.


Figure 4 shows a scatter plot of winter DAIN against salinity at all sites. This shows that there is a general relationship between elevated nitrogen and low salinity (fresh water), although there are also several elevated results with high salinity in the Medina Estuary.



Figure 4 Scatter plot of winter DAIN vs salinity at all sites, data from 1990 to 2015 (where where winter is November to February).

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Winter DAIN vs Salinity

Figure 5 shows the winter DAIN data spatially on a map of the Medina. This shows that winter nutrient concentrations are lower towards the estuary mouth and higher near the top of the estuary where the rivers enter, reflecting the importance of riverine nutrient loads locally.

Figure 5 Average winter DAIN concentrations in the Medina Estuary and the Rivers Medina and Lukely Brook (1990 to 2015)




DAIN data for the last 25 years from sampling points in the two main freshwater rivers (River Medina and Lukely Brook) is shown in Figures 6 and 7. The data suggest that overall DAIN levels in the River Medina have decreased over the last 25 years whereas DAIN levels in the Lukely Brook have increased (although there is no data from 2005 to 2012).

Figures 6 & 7 Trends in riverine DAIN at lowest sampling points in the River Medina and Lukely Brook (1990 to 2015)



Trends in nutrients in the Medina Estuary

Nitrogen levels in the Medina Estuary over time are shown in Figure 8 (mid estuary) and Figure 9 (nearest to inflowing rivers). Sites near the harbour mouth had insufficient data for temporal trend analysis. Data from the other four sites in the Medina Estuary are shown in Appendix 1. Figures 8 and 9 suggest that nitrogen levels in the Medina Estuary have not much changed over the last 25 years.

Figures 8 & 9 DAIN concentrations mid-estuary and in the estuary mouth to 2015 (Please note different scales for DAIN on the two graphs)

Site Y0004361 mid-estuary at Folly Inn, 1990-2015

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Y0004361 - Medina Estuary at Folly Inn

Site Y0004369 nearest the river inputs, 1992-2015

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Y0004369 - Medina Newport Docks



The estuarine winter DAIN data have been analysed prior to and following the diversion of Fairlee STW outfall out of the estuary in 2010, to see if there is any evidence of decreased nitrogen following this change. (The NVZ designation occurred in a similar period, in 2008, with implementation of measures in the catchment progressing during subsequent years). Table 2 shows the data before Fairlee diversion (up to 2010) and after diversion (2011 to present). Figure 10 presents the data spatially on a map of the estuary. There are only three sites where both pre and post designation data is available.

Table 2 DAIN data before and after diversion of Fairlee STW in 2010

Winter Average (mg/l)

Winter Average (mmol/m3)

1994-2010

2011-2015

1994-2010

2011-2015

Y0004369 MEDINA NEWPORT DOCKS 5.22 4.62 372.4 329.5

Y0004366 MEDINA VALLEY CENTRE 2.61 186.1

Y0004361 MEDINA ESTUARY AT FOLLY INN 1.11 0.987 79.18 70.47

Y0004385 MEDINA-SHELLFISH WATER 0.486 0.666 34.70 47.54

Y0004438 MEDINA SHELLFISH - CEFAS BED REF - B063B 0.494 35.25

Y0004356 MEDINA ESTUARY, WEST COWES-*CLOSED* 0.508

Data in red shows it exceeds the CSTT winter DAIN standard of 12 mmol/m³

Figure 10 Mean winter DAIN concentration before and after diversion of Fairlee STW



There is no clear overall trend in the data following diversion of Fairlee STW but it is clear that the Medina Estuary remains subject to elevated nutrients in the period following the diversion of Fairlee STW and the NVZ designation.

In summary, all the data confirm that the Medina Estuary remains hypernutrified (high in nutrients) throughout the period. There are some signs of a reduction in nutrients the River Medina; nutrients in the Lukely Brook, however, have increased.

Chlorophyll data and planktonic algal blooms

The Medina Estuary does not exhibit high chlorophyll concentrations or significant phytoplankton blooms. Its status as an SA(E) andPW(E) relates only to macroalgal growth.

Recent WFD phytoplankton data confirm that the Medina is of consistently HIGH status for Phytoplankton, demonstrating that phytoplankton blooms are not of concern. The tool on which this classification is based includes an analysis of chlorophyll concentrations. Chlorophyll concentrations from 2009 to 2015 are consistently within the chlorophyll standard.

The annual average chlorophyll concentrations shown in Table 1 demonstrate the low chlorophyll concentrations found in the Medina.

Macroalgae

Previous studies of macroalgae within the Medina Estuary in the early 2000’s reached the conclusion that the Medina should be designated as a Sensitive Area in 2007. Macroalgae surveys with aerial photography taken in 2002 and 2003 concluded that macroalgae (25 to 100% cover) covered 42 to 50 ha of the intertidal area, exceeding the ‘25% of the intertidal area’ UWWTD criteria in both surveys. This review resulted in the recommendation of consent conditions for nitrogen stripping at the qualifying sewage discharge from Peel Common STW, which was implemented in 2008. The review also endorsed the diversion of the qualifying sewage discharge from Fairlee STW to Sandown STW, and this was implemented in 2010.

In the 2005 Habitats directive Review of Consents, the quantity of macroalgae in the Medina was considered to contribute to adverse effect on site integrity in Solent and Southampton Water SPA (of which the Medina Estuary is part). The review also endorsed the diversion of Fairlee STW and recommended more stringent consent conditions for nitrogen stripping at Peel Common STW which was delivered in 2015.

More recently macroalgae in the Medina Estuary has been assessed under the WFD. The WFD classification method uses data on percent cover, biomass and the presence of entrained algae. Macroalgae surveys in the Medina were undertaken in 2008, 2012 and 2015 using remote sensing methods based on aerial imagery. Interpretation of the aerial images concluded that between 16 and 44 ha of the intertidal area was covered in macroalgae. This represents between 20 and 55 % of the available intertidal area and exceeds UWWTD criteria in 2012 and 2015.

Taken together, the 2008 and 2012 WFD surveys indicate that the Medina would only achieve Moderate status for macroalgae under WFD (EQR* score of 0.56). No classification is yet available for the 2015 survey. Some areas of entrained macroalgae were present in the WFD surveys.

* The WFD classification is reported as an Ecological Quality Ratio (EQR). The EQR value ranges from 0 to 1. An EQR with a value of 1 represents reference conditions and a value of 0 represents a severe impact.


Figure 11 shows the variability in the extent of macroalgae in the Medina Estuary during the different surveys. The least macroalgal cover was recorded in the summer of 2008 with approximately 16 ha recorded; much higher macroalgal cover was recorded in the other surveys (up to 50 ha). The lower amount in 2008 is likely to represent natural inter-annual variability; there is little evidence of a temporal trend in macroalgal cover. Further macroalgal monitoring in future is recommended given the high inter- annual variability in the Medina.



Figure 11: Extent of macroalgae in the Medina Estuary (Summer 2002 to 2015)

Seasonal macroalgal biomass surveys

Two sites in the Medina Estuary have been monitored for seasonal changes in macroalgae. Macroalgal biomass was measured every two months to assess how macroalgae varies throughout the year and whether it persists over winter. The sites at the Folly Inn and Newport-Hurst Lake (see Figure 2) have been regularly monitored between May 2004 and May 2006. The results are shown in Figure 12.

Figure 12 Macroalgal seasonal biomass at the Folly Inn and Newport-Hurst Lake in the Medina

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The results show the summer biomass of macroalgae generally exceeds 500 g/m2 at these sites, and can exceed 1000g/m2 at the Folly Inn. The peak biomass of up to 2.9 kg/m2 occurs in May. Macroalgae do not survive the winter months of January to March – biomass declines to less than 30g/m2 in March.



Overall, the macroalgae evidence clearly indicates that macroalgae is still a problem in the Medina Estuary based on the combination of extent, percentage cover and biomass. There is some entrained macroalgae but macroalgae does not persist over winter.








If overwintering macroalgae is present at the same time as important overwintering birds (for which the site is designated under the Habitats Directive), the macroalgae may interfere with feeding patterns and prey distribution. However macroalgae is not present in the winter months in the Medina Estuary.

If present, entrained macroalgae and overwintering macroalgae reduces the time and opportunity for the mudflats to recover from its adverse effects. There are some areas of entrained macroalgae in the Medina Estuary.



12) List the current WFD status/potential for any WFD waterbodies within the SA(E)/PW(E)

Waterbody ID WaterbodyName Current overall status

2015

Ecological status

2015


Status of Phys-chem supporting elements 2015

Phytoplankton Macroalgae Angiosperms Disolved Inorganic Nitrogen

Dissolved Oxygen

GB5207010101600 MEDINA

(Transitional water body)

Moderate Moderate High Moderate Moderate High

Based on the Environment Agency’s latest (December 2015) weight-of-evidence assessment for certainty of eutrophication, the Medina Estuary currently comes out as “Quite Certain of a eutrophication problem”. Further details of the weight-of-evidence approach are set out in the method statement for waters subject to eutrophication (Defra, 2016).


The Medina transitional waterbody is failing the DIN standard for WFD (Moderate status). .

There is a groundwater contribution to the Medina Estuary from the Central Downs Chalk groundwater body, which is currently at poor status for groundwater

quality due to rising trends in nitrate. This groundwater body failed the Drinking Water Protected Area test for nitrate. However, the majority of groundwater contribution to the estuary comes from the Lower Greensand aquifer, which is not failing for nitrate.




DIN is classified as Moderate under the WFD and winter DAIN exceeds standards used to assess UWWTD compliance, indicating that the Medina Estuary is hypernutrified throughout. Average levels of DAIN in the two main inflowing streams have shown some change over the period monitored (up to 25 years): DAIN levels have decreased slightly in the River Medina and increased slightly in the Lukely Brook.

The primary symptom of eutrophication in the Medina Estuary is the development of extensive mats of green macroalgae, primarily Enteromorpha spp. and Ulva spp., in intertidal areas throughout the harbour. Macroalgae in the Medina is classified as Moderate status under the WFD. Macroalgae surveys in 2008, 2012 and 2015 indicate that macroalgae cover between 20 and 55 % of the available intertidal area, exceeding UWWTD criteria in 2012 and 2015. Further macroalgae monitoring is recommended particularly as there is significant inter annual variability in macroalgal growth. The summer biomass of macroalgae generally exceeds 500g/m2 in sheltered sites (eg the bi-monthly monitoring sites). There is some entrained macroalgae but macroalgae does not persist throughout the winter.

There is therefore clear evidence that there remains a eutrophication problem in the Medina Estuary.

15) Summary of eutrophication control measures (already in progress and/or already planned) if any, for

the existing area.

Statutory measures

The Medina Estuary was designated an SA(E) in 2007 and, improvements at Fairlee STW and Peel Common STWs were made. Fairlee was diverted to discharge offshore at Sandown in 2010 and Peel Common was improved in 2008 (UWWTD) and 2015 (Habitats Directive).

The Medina was designated a PW(E) in 2008 and the catchment draining to it was designated an NVZ (see Figure 1). This means that specific farming practices are controlled in the designated area to reduce nitrogen losses from agriculture to water. The NVZ designation:




Voluntary measures

There are additional also voluntary measures in place within the catchment draining to the Medina Estuary. These measures derive from advice and incentives to farmers and landowners to reduce nutrient inputs to water, and include:





Form G (effects of enhanced treatment) Page 57

Ref. Code: ET7




1) Designated Site name: Medina Estuary (take name from Form A)


Running freshwater

Still freshwater

Y Estuarine water

Coastal water

3) Summary of qualifying sewage treatment work discharges (copy info from Form A)

Candidate name: Medina Estuary


Direct/Indirect

NGR Population Equivalent


(>10,000 PE)

Fairlee STW Direct SZ 3315 9187 -

Was diverted to Sandown STW in

2010. Sandown STW is distant

(discharges offshore) and has no

impact on the Medina.

Peel Common

STW Indirect SZ5780097800 246,851 TER

Total PE 246,851

Remarks:

Note: The Medina Estuary also receives sewage effluent from other STWs as follows, but these works are too small, or contribute too little, to qualify under the UWWTD; but they were including in all modelling work as discussed in section 5 below:

STWs in the freshwater rivers (eg Chale STW and Chillerton STW on the River Medina)

Large marine STWs discharging outside the harbour into the Solent (with water exchange at the harbour entrance)

The locations of these other STW sources are shown on the map in Appendix 2.

4) Summarise the comparative impact of the discharges (e.g.compare chemical and biological data upstream and downstream of the sewage discharge) in relation to pre-designation.



N/A

5) Where available provide estimates of nutrient loading for contributions for both qualifying sewage treatment work discharges and agricultural sources. Summarise how this has changed over time

Annual nitrogen contributions to the Medina Estuary were calculated for WFD nutrient investigations. The contributions were calculated taking into account the diversion of Fairlee STW and improvements at Peel Common STW. They are shown in Figure 13 (which is colour coded to show contributions from marine sources in blue, river sources in greens and sewage sources in reds).

Figure 13 Relative contributions of all nitrogen sources within the Medina Estuary

Freshwater Intermittents = 1%

Freshwater Urban Diffuse = 5%

Freshwater STWs = 3%

Freshwater Rivers (Medina & Lukely Brook) = 68%



Offshore Test = 3%

Offshore Itchen = 2%

Southampton Water STWs = 1%

Notes:

The map in Appendix 2 should be viewed in association with this source apportionment information as it shows the locations of the rivers and point sources refered to.

The data is derived from model outputs from CPM, SAGIS and Telemac models.

These figures confirm that over two thirds of nitrogen in the Medina Estuary (about 68%) is from direct freshwater diffuse agricultural sources, 12% is from offshore coastal background sources and 11% is from indirect rivers and STW inputs via offshore. The remainder (9%) is from STW, urban and intermittent inputs into the direct freshwater rivers (the freshwater STWs include Chale and Chillerton STWs).

The figures support the Polluted Water designation as the biggest nitrogen contribution (about 68%) is from agricultural sources in the Medina catchment.




Annual DAIN concentrations over time in the River Medina and Lukely Brook are shown in Figure 14.

In the River Medina overall DAIN levels have decreased (see Form D Figure 6). Figure 14 suggests that DAIN was highest in the mid 1990s/early 2000s but has remained at slightly lower levels for the last 10 years. The decrease in nitrogen in River Medina does not appear to be associated with the NVZ designation in 2008 as levels decreased in about 2005 and have since remained similar. Groundwater baseflow to the River Medina is relatively low in nitrate.

In the Lukely Brook overall DAIN levels have increased over time (although there is no data from 2005 to 2012). This may be partly because of the influence of groundwater. Groundwater baseflow to the Lukely Brook is relatively high in nitrate; nitrate in groundwater takes for a long time to travel to the water table so consequently it will take years to see the results of measures to reduce nitrate loading in the catchment.

Figure 14 Trends in annual average DAIN in the River Medina and Lukely Brook (1990 to 2015)

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2008



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Nitrogen concentrations from Peel Common indirect STW discharge to the Solent have significantly reduced since nutrient removal was installed starting in December 2008 (Figure 15).

Figure 15 Annual average concentration of DAIN in final effluent from Peel Common STW 1995-2015. (This STW discharges outside the Medina Estuary and is large enough to qualify under the UWWTD).

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Peel Common STW


Statutory measures

2008



The Medina Estuary was designated an SA(E) in 2007 and improvements at Fairlee STW and Peel Common STWs were made. Fairlee was diverted to to discharge offshore at Sandown in 2010 and Peel Common was improved in 2008 (UWWTD) and 2015 (Habitats Directive).

The Medina was designated a PW(E) in 2008 and the catchment draining to it was designated an NVZ (see Figure 1). This means that specific farming practices are controlled in the designated area to reduce nitrogen losses from agriculture to water. The NVZ designation:




Voluntary measures

There are additional also voluntary measures in place within the catchment draining to the Medina Estuary. These measures derive from advice and incentives to farmers and landowners to reduce nutrient inputs to water, and include:





There is no evidence that the eutrophication status of the Medina Estuary has changed – it is still eutrophic as shown by all the evidence above.

The coastal background source is a sizeable nutrient source to the Medina Estuary and this is anticipated to reduce very slowly over time, reflecting improvements in agricultural diffuse and sewage sources throughout the Solent area. Sewage discharges are a relatively small nutrient source and many of the larger sewage discharges have already been tackled via nutrient stripping and STW diversion schemes. Agricultural diffuse sources are by far the biggest nutrient source to the Medina and further reductions from this sector are anticipated as the uptake of statutory and regulatory measures continues.

Any changes are likely to take a long time for reasons including:

nutrients will take a long time to decrease in groundwater

STW improvements were relatively recently delivered

uptake of some agricultural measures is ongoing

the changes in nutrient loadings are relatively are small

there are a variety of nutrient sources

there is a natural biological time lag

there is inter-annual variation in natural factors like the weather


Nutrient control measures should not be removed as the process of nutrient reduction in the Medina Estuary will take a long time as outlined above. A steady concerted effort to reduce different nutrient sources to the harbour is ongoing and this should not be interrupted or stopped.

If nutrient control measures were removed the Medina Estuary might never change its status as a eutrophic water body.


Appendix Page 62

Appendix 1

Graphs of DAIN concentrations in the rest of the Medina Estuary to 2015

Site Y0004366 Medina Valley Centre (2011-2015)

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Appendix Page 63

Site Y0004438 Medina Shellfish - Cefas Bed Ref B063B (2011-2015)

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Site Y0004356 Medina Estuary, West Cowes (1992-2015)

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Appendix Page 64

Appendix 2 Locations of the rivers and sewage treatment works (STWs) used in the modelling to calculate the contribution of nitrogen from each source into the harbours in the Solent area. Please note that all the small STWs in each of the freshwater catchments are included in the model, but may have not been included on this map.

Medina Estuary

NVZ Name: Eastern Yar (Bembridge Harbour) NVZ ID: ET7

Medina Estuary


DATASHEET:



Report for existing Polluted Water Eastern Yar (Bembridge Harbour)

Page 67

Introduction
















Form A (Cover Sheet) Page 68

Ref. Code: ET7




Nitrates Regulations: Polluted Waters (Eutrophic) leading to Nitrate Vulnerable Zone (NVZ) designation

Form A: Cover Sheet




England England &

Wales Wales

England & Scotland




Eastern Yar (Bembridge Harbour)


Eastern Yar


Whole harbour - see Figure 1


Running freshwater

Still freshwater

Y Estuarine water

Coastal water


Sensitive Area (Eutrophic)







A previous Sensitive Area review concluded the contribution of nutrients from STWs is extremely small. Hence there are no qualifying sewage treatment works and the Eastern Yar (Bembridge Harbour) is only a Polluted Water (Eutrophic).

Candidate name: Eastern Yar (Bembridge Harbour)

Name of discharge

Direct / Indirect


Current Treatment




Total PE

Note: Bembridge Harbour receives sewage effluent from STWs, but these works are too small or contribute too little, to qualify under the UWWTD, but they are included in all the modelling work as discussed on page 21. The locations of these other STW sources and rivers included in the model are shown in Figure 16 in the Appendix.


The Eastern Yar (Bembridge Harbour) was designated as a Polluted Water under the Nitrates Directive in 2008. As a result of this designation the catchment draining into Bembridge Harbour was designated as a Nitrate Vulnerable Zone (NVZ). Later as part of the Habitats Directive Review of Consents the catchment was included as part of the Solent Diffuse Water Pollution Plan which was set up to tackle diffuse nutrient sources in the Solent European Marine sites. More recently in 2015, Southern Water diverted the small Brading STW discharge (currently discharging into the freshwater river), to the long sea outfall offshore at Sandown. This transfer will have the benefit of reducing the direct nitrogen load from sewage sources to Bembridge Harbour by an estimated 3%.

At the time of the designation there was evidence that Bembridge Harbour was eutrophic, based on the widespread growth of the opportunistic macroalgae Enteromorpha spp. and Ulva spp. Macroalgal surveys undertaken in 2003, indicated that macroalgae covered 36% of the intertidal area.

This review focuses on nutrients and macroalgae because other potential indicators such as dissolved oxygen sags and phytoplankton blooms have never been an issue in Bembridge Harbour (summary information is presented to confirm this).

Evidence from more recent studies show that Bembridge Harbour remains hypernutrified with nitrogen concentrations exceeding the standards used to assess UWWTD compliance and producing a classification of Moderate under the Water Framework Directive (WFD). Similarly macroalgal cover remains high. Macroalgal surveys undertaken in 2012 and 2015 indicate that macroalgae covers between 28% and 42% of the available intertidal area. These levels of cover exceed UWWTD guidelines, and are similar to pre-designation levels. The WFD macroalgae classification is Moderate, based on the combination of percentage cover and biomass. There is therefore clear evidence that there remains a eutrophication problem in Bembridge Harbour. However the macroalgae is not buried in the sediment and it does not persist throughout the winter months and therefore will have limited impact on overwintering birds.

The nutrient budget for Bembridge Harbour shows that diffuse riverine sources of nitrogen from the Eastern Yar dominate (51%) and approximately a quarter is from offshore coastal background sources. The modelling supports the Polluted Water designation in that the biggest nitrogen contribution is from agricultural sources in the Eastern Yar river catchment.



Current measures to reduce nitrogen into Bembridge Harbour from agricultural and sewage sources include a mixture of statutory and voluntary measures. Statutory measures include mandatory agricultural practice rules in the NVZ known as the Action Programme Measures. Voluntary measures derive from advice and incentives to farmers and landowners and include Catchment Sensitive Farming projects, Environmental Stewardship Schemes and other measures detailed in the Solent Diffuse Water Pollution Plan.

Nutrient control measures should not be removed as the process of nutrient/ eutrophication reduction in Bembridge Harbour will take a long time for a variety of reasons including the relatively recent and/or ongoing implementation of measures, the variety of sources, natural biological time lag and natural inter-annual variation.

A steady concerted effort to reduce different nutrient sources to Bembridge Harbour is ongoing and this should not be interrupted or stopped.









Form D (information, data, evidence) Page 71 Page 3

Ref. Code: ET7




1) Designated Site name: Eastern Yar/Bembridge Harbour (take name from Form A)


The PW(E) designation covers the whole of Eastern Yar/Bembridge Harbour (see Figure 1)

Start point NGR 1:SZ 63436 89285 NGR 2: SZ 63057 88600

End point NGR 3:SZ 63870 88753 NGR 4: SZ 64143 88693

Surface area (ha): 36ha (approx area below Mean High Water)


See Figures 1, 2 and 3

4) Approximate retention/flushing time (days): less than 3 days


The river Eastern Yar drains a predominantly rural catchment with an approximate area of 92km2 and discharges into the Solent via Bembridge Harbour. Bembridge Harbour has an approximate area of 0.36km2 with a further 0.68km2 in the outer embayment. It also has an old millpond which drains into the north of the harbour (Figure 1). At low tide the harbour drains almost entirely leaving intertidal mudflats. Consequently a large proportion of water will be exchanged on each tide and the flushing time is very short.

Bembridge Harbour is included within the Solent and Southampton Water SPA. The adjacent brackish lagoons are included with the Solent and Isle of Wight Lagoons SAC. The harbour is a Ramsar site and a SSSI. The estuary of the Eastern Yar comprises a wide range of nationally important estuary and associated coastal habitats and supports large numbers of overwintering wildfowl and waders which form an important component of the internationally important bird populations of the Solent. Natural England advises that eutrophication, due to elevated nitrogen, is a recognised threat to the condition of the designated sites, particularly through increased macroalgal abundance.

The SPA is a Protected Area under the EC Water Framework Directive and Marine Protected Areas (MPA) under the EC Marine Strategy Framework Directive. The reported MPA target is to restore water quality to



mean winter dissolved inorganic nitrogen levels at which biological indicators of eutrophication (opportunistic macroalgal and phytoplankton blooms) do not affect the integrity of the sites and features.

Bembridge Harbour is a popular recreational area with facilities for small boats and yachts. The harbour is popular with bird watchers and is a popular tourist location. In the outer embayment there is a designated bathing water (St Helens). The north-east side of the harbour is protected by St. Helens Duver; a sand and shingle spit partly owned and managed by the National Trust.


Y Amenity Y Boating


Y EC Bathing Water Angling

Commercial fishery Designated EC Shellfish Water

Designated EC Shellfish Harvesting Area



1. 2.

3. 4.




BRADING MARSHES TO ST. HELEN'S LEDGES Site of Special Scientific Interest (Wildlife and Countryside Act 1981, as amended)

The estuary of the Eastern Yar supports an extensive and diverse range of wetland habitats including saline and freshwater lagoons, botanically rich ditches, reedbeds, intertidal mudflats and sandflats. The intertidal mudflats, sandflats, eelgrass beds, and shingle, together with Brading Marshes, support large numbers of overwintering wildfowl and waders which form an important component of the internationally important bird populations of The Solent.

Natural England advises that eutrophication, due to elevated nitrogen, is a recognised threat to the condition of the designated sites, particularly through increased macroalgal abundance.

The SPA is a Protected Area under the EC Water Framework Directive and Marine Protected Areas (MPA) under the EC Marine Strategy Framework Directive. The reported MPA target is to restore water quality to mean winter dissolved inorganic nitrogen levels at which biological indicators of eutrophication (opportunistic macroalgal and phytoplankton blooms) do not affect the integrity of the sites and features.

8) What chemical data are available?



Y Chlorophyll-a

Cell counts

Dissolved Oxygen




Angiosperms


Y Macroalgae



Photographs

The Nitrate Vulnerable Zone designation in the Eastern Yar catchment was established following its designation as a Polluted Water (Eutrophic) under the Nitrates directive in 2008 (Figure 1).

The 2005 Sensitive Area review concluded that the contribution of nutrients from sewage treatment works (STWs) was extremely small. Hence there are no designated sewage treatment works and Bembridge Harbour is only a Polluted Water. However even though these STWs are too small or contribute too little to qualify under the UWWTD, they have been including in the modelling work summarised on page 21.

Figure 1: Map showing Bembridge Harbour (extent of Water Framework Directive water body), Polluted Waters (Eutrophic) and rivers. The extent of the NVZ in the catchment is shown hatched in yellow.

Note: Bembridge Harbour receives sewage effluent from STWs, but these works are too small or contribute too little, to qualify under the UWWTD and therefore are not shown in Figure 1, but they are included in all the modelling work. The locations of nutrient sources from STWs and rivers included in the model are shown in the map in Appendix 1.

Eastern Yar

Bembridge Harbour



The Eastern Yar WFD water body boundary overlaps with the Polluted Water designation but continues further out to sea. In addition the WFD water body splits into two along the boundary of the old millpond (Figure 2).

Figure 2: Bembridge Harbour showing the extent of the PW(E) and WFD water body

Figure 3: Bembridge Harbour showing water sample points from the marine and freshwater environment and the biological sample point for seasonal marcroalgae.

Easter Yar

(Bembridge Harbour)

Solent



The locations of discharges which are not qualifying have been included in the model are shown in Figure 16 in Appendix 1

Nutrients

Nutrients have been monitored at monitoring points throughout Bembridge Harbour. Table 1 below summarises DAIN (Dissolved Available Inorganic Nitrogen) and DAIP (Dissolved Available Inorganic Phosphorus) data to 2015 for each site in the estuary, showing annual average and winter average concentrations (where winter is November to February).

Table 1: Summary of Chemical data for Bembridge Harbour:

Site Code Annual Average

Data Start

Year

Count

(DAIN)

Chlorophyll

(ug/l)

DAIN

(mmol/m3)

DAIN

(mg/l)

DAIP

(mmol/m3)

DAIP

(mg/l)

Salinity

(ppt)

Y0004443 BEMBRIDGE HARBOUR - EASTERLY PONTOON ON SOUTH QUAY 2005 41 3.580 34.454 0.483 0.751 0.023 29.644

Y0004398 BEMBRIDGE HARBOUR - HM PONTOON 1992 152 11.976 84.316 1.181 1.115 0.035 28.540

Y0004444 SEAWARD END OF BEMBRIDGE SAILING CLUB LANDING STAGE 2005 41 2.555 26.748 0.375 0.649 0.020 32.019

G0006438 EASTERN YAR AT MOUTH 2011 6 20.312 0.285 0.769 0.024 34.235

Y0004287

from 2011 ST HELEN DUVERS 1992 6 14.910 0.209 0.737 0.023 34.213

Site Code Winter Average

Data Start

Year

Count

(DAIN)

Chlorophyll

(ug/l)

DAIN

(mmol/m3)

DAIN

(mg/l)

DAIP

(mmol/m3)

DAIP

(mg/l)

Salinity

(ppt)

Y0004443 BEMBRIDGE HARBOUR - EASTERLY PONTOON ON SOUTH QUAY 2005 15 0.953 43.265 0.606 0.793 0.025 31.988

Y0004398 BEMBRIDGE HARBOUR - HM PONTOON 1992 52 0.920 114.699 1.607 1.092 0.034 27.802

Y0004444 SEAWARD END OF BEMBRIDGE SAILING CLUB LANDING STAGE 2005 16 1.610 51.078 0.715 0.747 0.023 29.840

G0006438 EASTERN YAR AT MOUTH 2011 6 20.312 0.285 0.769 0.024 34.235

Y0004287

from 2011 ST HELEN DUVERS 1992 6 14.910 0.209 0.737 0.023 34.213

The data in Table 1 shows that in all sampling locations nutrients exceed the CSTT* standards used to assess UWWTD compliance: these state that ‘hypernutrification’ exists when winter values of nutrient concentrations significantly exceed 12mmoles/m³ DAIN in the presence of at least 0.2mmoles/m³ DAIP’. The relevant data are shown in red in Table 1 for both winter and annual averages.


The annual Water Framework (WFD) classification for Eastern Yar Harbour is mainly Moderate from 2009 to 2015, but in 2012 it achieved GOOD status due to a bias in marine samples.

Note: Eastern Yar (Bembridge Harbour) has been shown by previous work to be nitrogen limited, so nitrogen is the key nutrient of concern for macroalgal growth. In this report nitrogen is also referred to as DAIN and DIN (Dissolved Inorganic Nitrogen) because this is the terminology used for nitrogen standards that relate to relevant EU Directives. Because Bembridge Harbour is nitrogen limited, phosphorus data is only shown initially to enable comparison with nutrient standards.




Seasonal averages are shown in Figure 4. Winter DAIN concentrations are higher than summer concentrations. This is more pronounced at sites which have more variable salinity and are influenced by freshwater nutrient inputs.

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Salinity Winter Mean

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Figure 4: Winter and Summer average DAIN and salinity in Bembridge Harbour from 1992 to 2015, with sampling sites arranged from river to mouth (where Y0004287 site is the Harbour Mouth and Y0004443 is the estuarine site nearest the River Yar). Note winter (Nov-Feb) and summer (May-Sep).

Not only are winter nutrients generally higher than summer nutrients, late winter nutrients give the best estimate of nutrients that will be available in summer to support primary production; mid-summer concentrations demonstrate if nutrients limit primary production in summer.




Winter DAIN concentrations ranged from 13 to 319 mmoles/m3 and the range in salinity from 1 to 35 ppt (Figure 5). The scatter plot of winter DAIN against salinity shows that there is a relationship between elevated nitrogen and low salinity (freshwater).

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Figure 5: Winter DAIN vs salinity data from 1992 to 2015 at all sites in Bembridge Harbour

Winter nutrient concentrations are lowest at the estuary mouth, they are highest to the west of the estuary where the River Yar enters the harbour.(Figure 6). This reflects the importance of riverine nutrient loads locally.

Figure 6: Average winter DAIN concentrations in Bembridge Harbour and the River Eastern Yar (1990 to 2015)



Trends in nutrients


DAIN data from the lowest sampling point in the freshwater Eastern Yar suggests that DAIN levels in the river have shown a slight decline from 2009. Annual average concentrations in the river ranged from 3 to 5mg/l DAIN. Maximum concentrations prior to 2009 were recorded at 6.4 mg/l, however maximum concentrations since 2009 have been less than 5 mg/l, suggesting some improvement in peak concentrations.

Figure 7: Trends in riverine DAIN at lowest sampling point in the Eastern Yar river from 1990 to 2015

Trends in nutrients in Bembridge Harbour

Figures 8 to 10 show winter and summer data collected at sample points within the Harbour over several years.

Site Y0004443 closest to the River shows an increase in DAIN concentration post 2012 (Figure 7). However the sampling programme changed in 2012 to collecting samples over a wide variety of tidal states. Nitrogen levels in the estuary are highly dependent on tidal state at which they have been taken. Figure 4 has shown that freshwater has a much higher concentration of DAIN than saline samples. Additional samples taken at mid-tide and lower salinities in the winter of 2012/2013 have therefore biased the long term trend assessment shown in Figure 7.



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Figure 8 DAIN concentrations in the upper estuary site Y0004443 from 2005 - 2014

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Bembridge Harbour - HM Pontoon

Figure 9: DAIN concentrations in the middle estuary at site Y0004398 from 1992 - 2014

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Figure 10: DAIN concentrations in the lower estuary at site Y000444 from 2005 - 2014

Low salinity samples



Long term data from the middle estuary and lower estuary (Figure 9 and 10) show a slight decrease after 2009.

Appendix 2 shows the data from all 4 sites for which data is available.

Comparison of winter DAIN levels before and after the designation of NVZ in the Eastern Yar catchment in 2008

The DAIN data can be analysed prior to and following the NVZ designation in 2008, to see if there is any evidence of decreased nutrients following designation. Table 2 shows the data prior to NVZ designation (up to 2007) and following NVZ designation (2009 to present).

Table 2: Average winter DAIN pre and post NVZ designation (note pre data only available at 3 sites)

1994-2007 2009-2015 1994-2007 2009-2015

Y0004443 BEMBRIDGE HARBOUR - EASTERLY PONTOON ON SOUTH QUAY 0.667 1.155 47.620 82.478

Y0004398 BEMBRIDGE HARBOUR - HM PONTOON 1.641 1.337 117.128 95.478

Y0004444 SEAWARD END OF BEMBRIDGE SAILING CLUB LANDING STAGE 1.104 0.620 78.784 44.237

G0006438 EASTERN YAR AT MOUTH 0.285 20.312

Y0004287

from 2011 ST HELEN DUVERS 0.209 14.910

Winter Average

(mmol/m3)Winter Average (mg/l)

The data in Table 2 shows a clear reduction in average DAIN in two out of three of the sites in the 7 years following NVZ designation in 2008.

Figure 11 below presents the data prior to and after NVZ designation in 2008 on a map. The two sites in the middle and lower estuary appear to have had a reduction in the average winter DAIN coinciding with the NVZ designation in 2008. However, an increase is seen at Y0004443 closest to the river, this is due in part to a change in the monitoring programme when samples were taken over a wider tidal range and therefore included a higher proportion of samples with lower salinities.

Figure 11: Mean winter DAIN concentration before and after NVZ designation in 2008



Overall the data confirms that Bembridge Harbour remains hypernutrified (high in nutrients) throughout. There are slight positive signs in the reduction of nitrogen in the river and some parts of the estuary but the levels of nitrogen remain very high throughout the monitoring period.

Interpretation and discussion of biological evidence:

Chlorophyll data and Phytoplankton status

Bembridge Harbour does not exhibit high chlorophyll concentrations or significant phytoplankton blooms. Its status as a PW(E) relates only to macroalgal growth.

Previous reviews for the UWWTD, Nitrates Directive and Habitats Directive Review of Consents concluded that there was no evidence of blooms of unusual scale or duration and that chlorophyll concentrations are generally within a salinity-based chlorophyll standard within Bembridge Harbour.

More recently, WFD phytoplankton data confirms that Bembridge Harbour is of consistently HIGH status for Phytoplankton: the tool on which this classification is based includes an analysis of chlorophyll concentrations. Chlorophyll concentrations from 2010 to 2014 are consistently within the chlorophyll standard. The WFD status of Bembridge Harbour is based only on chlorophyll as no phytoplankton species data has been collected.

The annual average chlorophyll concentrations shown in Table 1 demonstrate the low chlorophyll concentrations found in Bembridge Harbour.

Macroalgae

Previous studies of macroalgae in Bembridge Harbour reached the conclusion that Bembridge Harbour should be designated as a Polluted Water. Macroalgae surveys with aerial photography taken in 2003 concluded that denser macroalgae (25 to 100%) covered 13 ha of the intertidal area which included the Old Millpond. The levels exceeded the 25% of the intertidal area UWWTD criteria.

In the 2005 Habitats Directive review, the levels of macroalgae in Bembridge Harbour within the Solent and Southampton Water SPA were considered to have an adverse effect on a precautionary basis.

As a result of these studies it was recommended that Bembridge Harbour should be designated as a Polluted Water in 2008 with Nitrate Vulnerable Zones subsequently required in the whole of the Eastern Yar catchment.

Macroalgae surveys were undertaken in 2012 and 2015 using remote sensing methods based on aerial imagery covering the whole of the harbour. Interpretation of the aerial images concluded that 15.5 and 10 ha of intertidal area (including the millpond) was covered in macroalgae. This represents 42% and 28% respectively of the available intertidal area, which exceeds the UWWTD criteria.

The more recent 2012 and 2015 surveys were also assessed under Water Framework Directive, which excludes the Old Millpond. The WFD classification method uses data on extent, percent cover, biomass and the presence of entrained algae. Under the WFD the Eastern Yar Harbour (excluding the millpond) achieved MODERATE status in the 2014 classification. This was based only on the 2012 survey data of the Eastern Yar water body. The two surveys undertaken in 2012 and 2015 will be used for the 2016 classification (unconfirmed EQR scores of 0.54 and 0.58 respectively) and indicate that Bembridge Harbour would achieve MODERATE status for macroalgae in both 2012 and 2015.


Figure 12 shows the extent of macroalgae (greater than 15% cover) in Bembridge Harbour and Millpond has remained at similar levels to 2003. The least amount of macroalgae was recorded in the summer of 2015 with 10.23 ha recorded. Further macroalgal monitoring in 2016 to 2021 is strongly recommended to assess if there is a long term trend of improvement or just inter-annual variability.



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Figure 12: Extent of macroalgae in both areas of the Eastern Yar (Summer 2003 to 2015)

Over wintering macroalgae

Winter biomass surveys have also been undertaken at a single site in the south of Bembridge Harbour (location shown in Figure 3) to assess if macroalgae persists through the winter. The site was monitored bi-monthly between November 2014 and March 2015. Macroalgae was only present at an extremely low density and biomass in November (less than 10g/m2) and was not present at this site or the remainder of the harbour during winter months of January and March. The results are shown in Figure 13.

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Figure 13: Winter biomass at Bembridge in the Eastern Yar (May 2014 to March 2015)

The primary symptom of eutrophication in Bembridge Harbour is the development of extensive mats of green macroalgae, primarily Enteromorpha spp. and Ulva spp., in intertidal areas throughout the harbour. Macroalgae surveys in 2003, 2012 and 2015 indicate that macroalgae cover between 28 % and 42% of the available intertidal area. The average summer biomass of macroalgae for the whole of the harbour generally exceeds1000g/m2 . However there is no entrained algae and it does not persist throughout the winter.



In summary, the biological evidence clearly indicates that macroalgae is still a problem in Bembridge Harbour based on the combination of extent, percentage cover and biomass but there is no entrained macroalgae and it does not persist over winter.








If overwintering macroalgae is present at the same time as important overwintering birds (for which the site is designated under the Habitats Directive), the macroalgae may interfere with feeding patterns and prey distribution. However macroalgae is not present in the winter months in Bembridge Harbour possibly due to the greater exposure compared to the more sheltered mainland harbours.

If present, entrained macroalgae and overwintering macroalgae reduces the time and opportunity for the mudflats to recover from its adverse effects. However entrained macroalgae in not present in Bembridge Harbour possibly due to the exposure of this harbour.



12) List the current WFD status/potential for any WFD waterbodies within the SA(E)/PW(E

Waterbody ID Waterbody

Name

Current overall status

2015

Ecological status

2015


Status of Phys-chem supporting elements

2015

Phytoplankton Macroalgae Angiosperms Dissolved Inorganic Nitrogen

Dissolved Oxygen

GB520710102000 EASTERN YAR

Moderate Moderate High Moderate No data Moderate High

Note that these are Cycle 2 classification.

Based on the Environment Agency’s latest (December 2015) weight-of-evidence assessment for certainty of eutrophication, the Eastern Yar currently comes out as “Quite Certain of a eutrophication problem”. Further details of the weight-of-evidence approach are set out in the method statement for waters subject to eutrophication (Defra, 2016).


Eastern Yar transitional waterbody is failing the DIN standard for WFD.

There is only a very small contribution to the harbour from Chalk groundwater so the influence of trends in levels of nitrate in the groundwater will be small to the Eastern Yar transitional waterbody.


Winter DAIN levels exceed the UWWTD criteriaand the WFD good/moderate boundary and indicate Bembridge Harbour is hypernutrified throughout. Average levels of DAIN in the Eastern Yar River have decreased slightly since 2009.

The primary symptom of eutrophication in Bembridge Harbour is the development of extensive mats of green macroalgae, primarily Enteromorpha spp. and Ulva spp., in intertidal areas throughout the harbour. Macroalgae in Eastern Yar Harbour is classified as moderate status under the Water Framework Directive. Macroalgae surveys in 2003, 2012 and 2015 indicate that macroalgae cover between 28% and 42% of the available intertidal area (including the millpond). The summer biomass of macroalgae generally exceeds 1000g/m2 . However there is no entrained algae and the macroalgae does not persist throughout the winter and therefore will have limited impact on overwintering birds.



There is therefore clear evidence that there remains a eutrophication problem in Bembridge Harbour.

15) Summary of eutrophication control measures (already in progress and/or already planned)

if any, for the existing area.

Statutory measures

Southern Water has recently diverted the small Brading STW discharge into the freshwater river to Sandown STW, to be discharged offshore (see Appendix 1). This is being done to deliver a National Environmental Programme (NEP) improvement scheme required by the Environment Agency. The project, delivered in 2015, will have the benefit of reducing the direct nitrogen load from sewage sources to the Eastern Yar by an estimated 3%.

Bembridge Harbour was designated a PW(E) in 2008 and the catchment draining to Bembridge Harbour has been designated an NVZ (see Figure 1). This means that specific farming practices are controlled in the designated area to reduce nitrogen losses from agriculture to water. The NVZ designation:




Voluntary measures

There are also additional voluntary measures within the catchment draining into Bembridge Harbour. These measures derive from advice and incentives to farmers and landowners to reduce nutrient inputs to water, and include:



Solent Diffuse Water Pollution Plan which relates to several catchments that border the Eastern Solent and the Isle of Wight.



Ref. Code: ET7




1) Designated Site name: Eastern Yar (Bembridge Harbour) (take name from Form A)


Running freshwater

Still freshwater

Y Estuarine water

Coastal water

3) Summary of qualifying sewage treatment work (STW) discharges (copy info from Form A)

The Eastern Yar (Bembridge Harbour) is only a Polluted Water (Eutrophic) as the contribution of nutrients from STWs is extremely small. Hence there are no qualifying sewage treatment works.

Candidate name: Eastern Yar (Bembridge Harbour)


Direct/Indirect NGR

Population Equivalent


(>10,000 PE)

None

Total PE

Remarks: The 2005 Sensitive Area review concluded the contribution of nutrients from STWs is extremely small. Hence there are no qualifying sewage treatment works and Bembridge Harbour is only a Polluted Water.

Note: Bembridge Harbour receives sewage effluent from STWs, but these works are too small or contribute too little to qualify under the UWWTD, but they are included in all the modelling work as discussed in section 5 below:

Small STWs, including those in freshwater river Eastern Yar (including St Helens and Brading STW)

Large marine STWs discharging outside the harbour offshore (with water exchange at the harbour entrance) The locations of these other nutrient sources from STWs and rivers included in the model are show in the map in Appendix1.

4) Summarise the comparative impact of the discharges (e.g. compare chemical and biological data upstream and downstream of the sewage discharge) in relation to pre-designation.

N/A



5) Where available provide estimates of nutrient loading for contributions for both qualifying sewage treatment work discharges and agricultural sources. Summarise how this has changed over time.

Annual nitrogen contributions to Bembridge Harbour were calculated for WFD nutrient investigations. The contributions were calculated taking into account the nutrient reductions at many STWs around the Solent including smaller STWs (too small to be UWWTD qualifying discharges) in the Eastern Yar catchment. They are shown in Figure 14 (which is colour coded to show contributions from marine sources in blue, riverine sources in greens and sewage sources in reds).

Notes:

The map in Appendix 1 should be viewed in association with this source apportionment information as it shows the location of the rivers and point sources refered to.

This data is derived from model outputs from CPM, SAGIS and Telemac models.

Figure 14: Relative contribution of all nitrogen sources combined within Bembridge Harbour

Available evidence from recent modelling work confirms that approximately half of the nitrogen in Bembridge Harbour is from freshwater diffuse sources from the River Eastern Yar and a quarter is from offshore coastal background sources The remainder is mostly from small STWs and urban diffuse sources in the River Eastern Yar.

The figures support the Polluted Water designation as the biggest nitrogen contribution (51%) is from agricultural sources in the River Eastern Yar catchment.

Southern Water has recently diverted the Brading STW discharge from the freshwater river to Sandown STW which is offshore. This is being done to deliver a National Environmental Programme (NEP) improvement scheme required by the Environment Agency. The transfer, delivered in 2015, will reduce the direct nitrogen load from sewage sources to the Eastern Yar. Brading STW contributes nearly 3% of the nitrogen load in the Eastern Yar estuary so removing the input from Brading STW would therefore reduce the nitrogen load in the estuary by almost 3%.



The remaining STWs in the catchment (Wroxall, Roud ,St Helens ,Godshill and Hazely Combe Arreton STWs) are too small to quality for UWWTD, and contribute approximately 2% each of the nitrogen load in the Eastern Yar estuary. Sandown STW which discharges offshore only contributes < than 1% of the nitrogen load to the estuary.


DAIN concentrations over time in the Eastern Yar River are shown in Figure 15. DAIN levels in the river have been decreasing since 2009 coinciding with the designation of the NVZ in the freshwater catchment. However concentrations are still high in the river and further monitoring for 2016 to 2021 is recommended to assess if there is a long term trend of improvement or just inter annual variability linked to climatic conditions.

There is only a very small contribution to the harbour from Chalk groundwater so the response to tackling diffuse sources in the Eastern Yar catchment is likely to be quicker than other catchments and rivers which have a significant contribution from groundwater such as Langstone Harbour.

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Figure 15: Trends in annual average DAIN in the River Eastern Yar at site Y0004399 (1990 to 2015)


Statutory measures:

Bembridge Harbour was designated a PW(E) in 2008. As a result all of the catchment draining into Bembridge Harbour was designated as an NVZ. Southern Water has recently proposed to divert the small Brading STW discharge into the freshwater river to Sandown STW, to be discharged offshore. This is being done to deliver a National Environmental Programme (NEP) improvement scheme required by the Environment Agency. The proposal, delivered in 2015, will have the benefit of reducing the direct nitrogen load from sewage sources to the Eastern Yar by an estimated 3%.



The catchment draining to Bembridge Harbour has been designated an NVZ (see Figure 1). This means that specific farming practices are controlled in the designated area to reduce nitrogen losses from agriculture to water. The NVZ designation:




Voluntary measures:

There are additional voluntary measures in place within the catchment draining into Bembridge Harbour. These measures derive from advice and incentives to farmers and landowners to reduce nutrient inputs to water, and include:



Solent Diffuse Water Pollution Plan which related to several catchments that border the Eastern Solent and the Isle of Wight.


There is no evidence that the eutrophication status of Bembridge Harbour has changed – it is still eutrophic as shown by all the evidence above.

The coastal background source is a substantial nutrient source to Bembridge Harbour and this is anticipated to reduce very slowly over time, reflecting improvements in agricultural diffuse and sewage sources throughout the Solent area. Sewage discharges are a relatively small nutrient source and many of the larger sewage discharges in the wider Solent area have already been tackled via nutrient stripping and STW diversion schemes. Agricultural diffuse sources are significant and further reductions from this sector are anticipated as the uptake of statutory and regulatory measures continues.

Any changes as a result of nutrient reductions from agriculture or sewage inputs are likely to take a long time for reasons including:

Uptake of some agricultural measures is ongoing

STW improvements only recently delivered

The changes in nutrient loadings are relatively small

There are a variety of nutrient sources (including nutrients in sediments)

There is a biological time lag

There is inter-annual variation in natural factors like weather


Nutrient control measures should not be removed as the process of nutrient reduction in Bembridge Harbour will take a long time as outline above. A steady concerted effort to reduce different nutrient sources to the harbour is ongoing and this should not be interrupted or stopped.

If nutrient control measures were removed Bembridge Harbour might never change its status as a eutrophic water body.


Appendices Page 90

Appendix 1

Figure 16: Locations of the rivers and STWs used in the modelling to calculate the contribution of nitrogen from each source into the harbours in the Solent area. Please note that all the small STWs in each of the freshwater catchments are included in the model, but may have not been included on this map.


Appendices Page 91

Appendix 2

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a Bembridge South Quay Easterly pontoon b Bembridge Harbour

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Figure 17 : Graphs of DAIN concentration from 1993 to 2015 at 4 sample points within Bembridge Harbou

Medina Estuary


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