38
Quantifying nitrogen loading from land to sea in Nassau County
Quantifying nitrogen loading from land to sea in Nassau County
Many impairments associated with nitrogen overload
Impaired
Minor impacts
No known impacts
Salt marsh ecosystems
Salt marshes protect coastlines
Salt marshes protect coastlines
Flooding during Hurricane Sandy
“Coastal eutrophication as a driver of salt marsh loss”, Deegan et al 2012, Nature
Healthy marsh Nitrogen loaded marsh
Nutrient Dense, weakened, strong roots roots
Loss of wetlands on Long Island, since 1974 90
80
Per
cen
t lo
ss s
ince
19
74
NYSDEC survey data 70
60
50
40
30
20
10
0 So
uth
Man
hasset B
ay
Man
hasset, M
ano
r Hav
en
Man
hasset, P
lum
Po
int
Man
hasset, K
ing
s Po
int
Peco
nics, C
orey
Creek
Mou
nt S
inai H
arbo
r
Flax
Pon
d
Sto
ny B
rook
Harb
or
Nisseq
uog
ue R
iver
Western
Bay
s, East B
ay
Western
Bay
s, Mid
dle B
ay
So
uth
Oy
ster Bay
, Go
ose Is.
So
uth
Oy
ster Bay
, Gilg
o Is.
Peco
nics, C
edar B
each C
reek
Suffolk County, North Shore
Nassau County, North Shore Suffolk County Nassau County
East end South Shore South Shore
Seagrass: Critical habitat
for fish and shellfish
NYS seagrass, 1930 - 2030 200,000
150,000 A
cres
of
seag
rass
100,000
50,000
0 Extinction in NY
1930 2009 2030
NYSDEC Seagrass Taskforce Final Report, 2010; Suffolk County assessment, 2014
Nitrogen promotes in the water impairments: algal blooms, low oxygen
Point Lookout, seaweed bloom: unsightly, contributes to low oxygen, low pH
Percent bottom coverage of Ulva sp. in Western Bays in the Fall of 2011.
Jones Inlet
Effects of nutrients on the growth of Ulva in the Western Bays
Control N P Si
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
Ne
t gr
ow
th r
ate
, d⁻¹
Excessive nitrogen loading can leads to low
Nitrogen loading
Phytoplankton
CH2O + O2 Respiration
CO2 + H2O Consumed Produced
“More algae and warm temperatures during summer make bacteria hyperventilate”
Minimum dissolved oxygen, summer 2016
= Good = Fair = Poor
Good: DO minimum > 5 mg/L Fair: DO minimum 3 – 5 mg/L Poor: DO minimum < 3 mg/L
NYS landings of shellfish, 1980 – 2010
-100 -90 -80 -70 -60 -50 -40 -30 -20 -10
0
Perc
ent
dec
line
sin
ce 1
98
0
Clams Oysters Scallops Mussels
Losses due to nitrogen driven harmful algal blooms, seagrass loss, and water quality degradation.
Has nitrogen mitigation helped hypoxia in Long Island Sound?
• Goal to reduce N loads by 58.5% • In 2014, close to reaching this goal. • Ecosystem response?
Reduction in Long Island Sound hypoxic area with 60% nitrogen reduction
Squ
are
mile
s o
f h
ypo
xia
(<2
mg
/L)
200
180
160
140
120
100
80
60
40
20
0
R² = 0.4627
2002 2004 2006 2008 2010 2012 2014 2016 2018
Planned re-routing of Bay Park sewage to Cedar Creek ocean outfall
Potential recovery of seagrass in Western Bays
Potential gain of nearly 3,000 acres of seagrass with sewage abatement.
Nitrogen Loading Model (NLM) components:
Atmospheric
Deposition
Fertilizer
Wastewater
Total N Load
How much nitrogen?
What is the source?
Nitrogen Loading Model (NLM) Overview:
Source: Latimer and Charpentier 2010
Nitrogen Loading Model (NLM) Overview:
13 Nassau County watersheds
Base Layers created:
Tax map and census identification of all
properties: Lot size, number of individuals
per home, size of buildings.
Lawn raster
Impervious raster
Lawn Raster High Resolution Normalized Difference Orthoimagery Vegetation Index > 80
Lawns
Where both
are true
LiDAR Object Height < .1m
Impervious Raster
High Resolution Normalized Difference Impervious
Orthoimagery Vegetation Index < 90
Atmospheric Deposition
N-Load from
Atmospheric
Deposition
Natural
Vegetation
Turf
Agriculture
Ponds
Wetlands
Roads
Residential
Impervious
Other
Impervious
Residential + Golf + Park Lawns
All area that is not included
below
Land Use Data
Land Use Data
Land Use Data
?
Impervious limited to Residential Parcels
Impervious total – Road – Res Impervious
Fertilizer
N-Load
from
Fertilizer
Agriculture
Residential
Lawns
Golf Lawns
Park Lawns
Land Use Data
Lawns limited to
Residential Parcels
Lawns limited to Golf
Course Parcels
Lawns limited to Park
Parcels
Wastewater
N-Load
from
Wastewater
Cesspools within
200m of shore
Cesspools outside
200m of shore
Septic systems within
200m of shore
Septic systems outside
200m of shore
Sewer Plants N Output
# of People
2010 Census
# of People
2010 Census
# of People
2010 Census
# of People
2010 Census
Lloyd Aquifer
Raritan Clay Confining Unit
Upper Glacial Aquifer
Water Table
Magothy Aquifer
Agriculture
Stream
Loading Rates (lb-N/A/yr)
Pasture/Hay: 20
Orchards: 70
Vineyards: 15 Sod: 250
“Other”: 110
40%
Atmospheric Deposition
0.04 lbs-N/1,000sf/yr
Leaching:
25% natural
30% turf
40% agriculture
Fertilizer inputs: Agriculture
Lloyd Aquifer
Raritan Clay Confining Unit
Upper Glacial Aquifer
Water Table
Magothy Aquifer
Parks/Golf
Courses
Stream
Atmospheric Deposition
0.04 lbs-N/1,000sf/yr
3.89 lbs-N/1,000sf/yr
20%Leaching:
25% natural
30% turf
40% agriculture
Fertilizer inputs: Parks, golf, homes
Homes2.5 lbs-N/1,000sf/yr
30%
Lloyd Aquifer
Raritan Clay Confining Unit
Upper Glacial Aquifer
Water Table
Magothy Aquifer
Residential
(unsewered)
Stream
Loading Rates
10 lbs-N/person/yr
U.S. Census Data
6% removal from tank
10% removal in “plume”
Atmospheric Deposition
0.04 lbs-N/1,000sf/yr
Leaching:
25% natural
30% turf
40% agriculture
Wastewater: residential
Lloyd Aquifer
Raritan Clay Confining Unit
Upper Glacial Aquifer
Water Table
Magothy Aquifer
Commercial
Stream
Atmospheric Deposition
0.04 lbs-N/1,000sf/yr
Leaching:
25% natural
30% turf
40% agriculture
Commercial:
0.07 gpd/sf x 60 mg/L
+ 2 residential units in
downtown areas
Industrial:
0.04 gpd/sf x 60 mg/L
Institutional:
0.06 gpd/sf x 60 mg/L
Wastewater: commercial
Sewage treatment plants: Wastewater (treatment facilities): Flow and concentration data for sewage
treatment plants subwatersheds. Averaged across years. Source NYSDEC or
EPA- ECHO.
Missing Data
The model is 90% done. Outstanding needs include.
Freshwater wetlands: Publicly available shapefile is clearly wrong.
Sewersheds for Suffolk and Queens Counties (some of the watersheds of Nassau extend into these counties).
Outfall Locations of Sewer Plants (Not facility location)
Roads: The shapefile available is for roads only has two categories: Local and Secondary. It would be nice to get a shapefile with more divisions, but maybe this is not necessary.
Next steps
Apply residence times to nitrogen loading rates to determine
nitrogen residence times.
Compiled water quality data from across the north and south shore
to compare to nitrogen residence times.
Rank watersheds?
