'Phase 2 Stream Geomorphic Assessment High Knob Brook Watershed', Milone and McBroom, Inc, February...

8/2/2019 'Phase 2 Stream Geomorphic Assessment High Knob Brook Watershed', Milone and McBroom, Inc, February 2009

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Phase 2 Stream Geomorphic Assessment

High Knob Brook Watershed

Town of Starksboro, VT

February 2009

Prepared for:

Lewis Creek Association

Charlotte, VT

Prepared by:

Milone & MacBroom, Inc.

South Burlington, VT

High Knob Brook T6.06 A

September 24, 2008


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Table of Contents

Executive Summary ....................................................................................................................................... i

1.0 Project Overview ............................................................................................................................. 1

2.0 Background ...................................................................................................................................... 1

2.1 Geographic Setting ............................................................................................................. 1

2.2 Geomorphic Setting ............................................................................................................ 3

2.3 Hydrologic Setting .............................................................................................................. 3

3.0 Methodology .................................................................................................................................... 3

3.1 Field Assessment Methods ................................................................................................. 4

3.2 Quality Assurance Methods ................................................................................................ 4

4.0 Results .............................................................................................................................................. 5

4.1 T6.06 ................................................................................................................................... 5

4.2 T6.05 ................................................................................................................................... 9

4.3 T6.04 ................................................................................................................................. 11

4.4 T6.03 ................................................................................................................................. 13

4.5 T6.02 ................................................................................................................................. 15

4.6 T6.01 ................................................................................................................................. 17

4.7 T6.31S.01 .......................................................................................................................... 19

5.0 Summary of Results ....................................................................................................................... 215.1 Geomorphic Results Summary ......................................................................................... 21

5.2 Habitat Results Summary ................................................................................................. 23

5.3 Bridge and Culvert Assessments ...................................................................................... 27

6.0 Habitat Recommendations ............................................................................................................. 28

6.1 T6.0 ................................................................................................................................... 28

6.2 T6.05 ................................................................................................................................. 29

6.3 T6.04 ................................................................................................................................. 30

6.4 T6.03 ................................................................................................................................. 316.5 T6.02 ................................................................................................................................. 32

6.6 T6.01 ................................................................................................................................. 33

6.7 T6.3S1.01 .......................................................................................................................... 33

7.0 References ...................................................................................................................................... 34


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Appendices

Appendix A Reach Location Maps

Appendix B Bridge and Culvert Assessment Reports

Acknowledgements

This project was completed in partnership with the U.S. Fish and Wildlife Service, Northeast

Region, specifically with the help of Madeleine Lyttle and Nick Sibley. The project was funded

by the Lewis Creek Association through its grant with the Vermont Department of

Environmental Conservation. Marty Illick of the Lewis Creek Association coordinated this

project. Technical assistance was provided by Shannon Pytlik and Shannon Bonney of the

Vermont Department of Environmental Conservation River Management Program.


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Executive Summary

A Phase 2 Stream Geomorphic Assessment was conducted on High Knob Brook (watershed area

= 5.2 square miles) in Starksboro, Vermont. The assessment utilized the Vermont rapid

geomorphic assessment and the newly developed reach habitat assessment protocols. The

assessment covers the entire stream length of High Knob Brook from the confluence with the

Lewis Creek upstream to the beginning of the defined channel (5.6 miles).

High Knob Brook drains a small mountain watershed before reaching the broad Lewis Creek

floodplain. The channel is dominated by wetlands, and then forms a defined channel in active

pasture land. In this headwater location the meadow stream (Rosgen type E) is trampled in

locations by active grazing in and along the channel and floodplain. Traveling downstream the

High Knob Brook gets steeper and becomes a riffle-pool channel in places, with periodic

sections of steep bedrock. Some encroachments such as homes and roadways exist in the river

corridor, yet overall the corridor is mostly undeveloped.

Stream reaches were segmented based on changes in channel morphology (E, C, B stream types),

buffer condition (pasture, meadow, and forested land cover), valley confinement (very broad or

narrower valley width), and river corridor encroachments (undeveloped or homes and roadways

present).

Geomorphic condition is generally similar to reference conditions. Of the 13 sites assessed, 2

were reference, 4 good, 4 fair, and 1 poor. Channel instabilities are generally caused by historic

channel alteration.

Preliminary stream restoration and protection recommendations were made based on results of

the habitat assessment. Streams had good (7 segments) to fair (4 segments) habitat relative to the

expected reference condition. River corridor protection from future development and

reestablishment of buffers in pasture areas is recommended along the entire corridor. Several

active restoration approaches such as riparian plantings and replacement of undersized culverts

would improve the system.


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1.0 Project OverviewA Phase 2 stream geomorphic assessment was completed in 2008 for the length of High Knob

Brook (T6.01 to T6.06) and one section of one of its tributaries (T6.3S1.01). Stream geomorphic

assessments provide a basis for understanding existing conditions relative to natural river form

and processes, and can guide planning efforts for conservation and restoration. The Vermont

Agency of Natural Resources (VTANR), through its River Management Program (RMP) has

developed a three-part Stream Geomorphic Assessment (VTANR, 2007). Phase 1 ofThe

Protocols, a map-based watershed assessment, identifies expected stream type based on its

valley. Phase 2 ofThe Protocols is a field exercise that identifies physical channel

characteristics (e.g., width, depth, slope, meander pattern, particle size distribution) via

observation and measurement, and verifies data collected during Phase 1. Phase 3 ofThe

Protocols consists of a survey assessment where expanded observations and field survey are

conducted to verify previous observations and create the detailed data set and site plan necessary

for the evaluation of restoration alternatives.

The Phase 1 Geomorphic Assessment for High Knob Brook was completed by South Mountain

Research and Consulting, in Bristol, VT (SMRC, 2007).

The Lewis Creek Association contracted with Milone & MacBroom, Inc. to complete the Phase

2 Assessment of High Knob Brook in 2008.

2.0 Background2.1 Geographic Setting

The assessment covers the entire stream length of High Knob Brook from the confluence with

the Lewis Creek upstream to the beginning of the defined channel. This tributary of Lewis Creek

drains a total area of 5.2 square miles (Figure 1). The High Knob Brook watershed is located

entirely within the Town of Starksboro. The stream runs along Big Hollow Road, travels south

through a remote area, passes under VT Route 116 and joins Lewis Creek at the upstream end of

mainstem reach M20. High Knob Brook was divided into 6 reaches during the Phase 1

Assessment and covers a total stream length of 5.6 miles. One reach of an unnamed tributary

(T6.3S1.01) was included in the assessment and was an additional 0.3 miles.


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Figure 1: High Knob Brook, Starksboro, Vermont.


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2.2 Geomorphic Setting

High Knob Brook slopes gently (S = 1.7%) downstream from its highest point at approximately

1,060 feet of elevation. Approximately 6,000 feet upstream from the confluence with Lewis

Creek, the channel has a locally steep slope (S = 14.2%) (Figure 2). From the confluence with

High Knob Brook, Lewis Creek flows another 26 miles before entering Lake Champlain.

Figure 2: High Knob Brook longitudinal profile is shown for all project reaches (USGS).

2.3 Hydrologic Setting

A USGS gage (watershed area = 5.3 sq mi) operated on High Knob Brook during the years 1963-

1974 and 1999-2000 near the Route 116 crossing (04282700, Lewis Creek Tributary at

Starksboro, VT). Peak flow regression analysis (Olson, 2002) indicated a 100-year flood of 704

cfs and a 10-year flood of 266 cfs. The 2-year flood, or approximate bankfull event, was

determined to be 118 cfs. Current peak flow estimates from the USGS StreamStats website

indicate 193, 362, and 668 cfs for the 2, 10, and 100-year floods.

3.0 MethodologyThe assessment followed protocols developed by the Vermont Agency of Natural Resources

(VTANR, 2007). Protocols were downloaded from the RMP website, and guidance for the new

rapid habitat assessment (Schiff et al., 2008) was previously obtained during method

development by MMI and RMP.


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3.1 Field Assessment Methods

All project reaches were assessed on foot following the VTANR protocols. Segment breaks were

identified during a stream walk based on cross section measurements and other reach data. A

sketch of the stream was made during the stream walk. Current geomorphic condition was

documented along with dominant channel processes at a representative cross section (i.e.

aggradation, degradation, widening, planform change).

The habitat assessment followed the 2008 protocols. Large woody debris, pools, undercut banks,

and identification of refuge areas were counted and measured during the stream walk and logged

on a tally sheet. Field forms were completed at the representative cross section to quantify key

habitat features on condition.

Bridge and Culvert assessments were completed for each structure in the project area using the

protocols in Appendix G of the Stream Geomorphic Assessment. Structure width, clearanceheight, length and general characteristics describing the interaction of the channel and structure

were recorded.

Assessments were completed between August 5, 2008 and November 6, 2008. Key physical and

habitat features were sketched and approximately located using a hand-held GPS unit (Garmin

GPS 76). Features were documented with a digital camera.

Features were indexed with reference to the Vermont Hydrography Dataset (VHD) using the

Feature Indexing Tool in the SGAT (Version 4.53) GIS extension. Reach segmentation was

recorded, where necessary, using the Segmentation Tool. Data was submitted online using theData Management System (DMS).

3.2 Quality Assurance Methods

All data were thoroughly examined in-house by MMI. Geomorphic stream type and channel

evolution stage were compared to various classification systems (e.g., Montgomery and

Buffington, 1993; Rosgen and Silvey, 1996; Rosgen et al., 2006) to verify decision-making in

the field. The data were submitted to RMP for QA review on December 8, 2008.


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4.0 ResultsResults of the stream geomorphic assessment for High Knob Brook reaches T6.01 T6.06, and

unnamed tributary T6.3S1.01 are presented here. Reaches and segments are presented from

upstream to downstream. Reference to right bank and left bank assume facing downstream.

Reach mapping can be found in Appendix A and data summary reports for each reach in

Appendices B and C.

4.1 T6.06

This reach marks the upstream limits of High Knob Brook, with the upper part of the reach

dominated by wetland. The Phase 1 reach reference stream type was changed from C to E based

on field observations of valley characteristics. This reach was divided into three segments.

Segment C contained mostly wetlands and overland flow without a clearly defined channel.

Segment B contained a well-defined channel with multiple encroachments in the river corridor.Segment A is largely ponded due to the presence of multiple beaver dams.

Segment C

The upstream-most segment on High Knob Brook is dominated by wetland characteristics and

was therefore not fully assessed since the assessment protocols refer to alluvial channels. The

segment was walked, sketched, photo-documented, and GPS points were taken to facilitate

feature indexing. Channel dimensions were not measured, as this segment did not have a defined

channel. The reach started in an herbaceous wetland field, which at the time of assessment was

flooded (Figure 3). This segment occupies a corridor approximately 65 feet wide confined

between the Big Hollow Road embankment on the right and a steep wooded hillside on the left.A private driveway crosses this segment with an undersized culvert, likely increasing flooding in

the upstream wetland. This segment includes a short section of wooded wetland before entering

the pasture downstream.

Figure 3: Wetland conditions in T6.06 segment C

looking downstream.


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Segment B

This segment is the upstream limit of a defined stream channel and is dominated by pasture and

occasional residential encroachments. The channel is a shallow, narrow E4 riffle-pool stream.

The channel is in fair geomorphic condition relative to its expected reference stream type and in

stage III of channel evolution (F model), indicating widening and aggradation due to historic

incision.

Cows and horses out to pasture have direct access to a significant portion of this segment both

upstream and downstream of a run-of-the river residential dam (Figure 4a). At the most upstream

end of the segment the channel is trampled, which appears to be leading to some localized

increases in erosion and deposition, and channel braiding (Figure 4b). The small channel size and

trampled channel in the pasture makes it unclear exactly where the stream would naturally

transition from wetland to defined water course. Nevertheless, the entire pasture was included inSegment B due to the departure from natural reference conditions.

The impoundment in the middle of this segment is dammed by a private driveway embankment.

The ponded area is much wider than the channel and filled with sediment and algae. This dam

appears to have one small outflow pipe that goes through the dam and into the downstream

channel. There was evidence of recent work on this dam, possibly due to damage during heavy

rains through July and August of this summer.

The influence of cows continues downstream of the dam, but the channel maintains a more

defined E stream type with less trampling than upstream. The channel flows through a shortsection of alder thicket just upstream of a home and barn on the right floodplain. There is

possible historic filling behind this home, and evidence of minor recent filling. A new culvert for

a trail crossing causes a minor constriction at the downstream end of the segment.

The RHA score for this segment is in the lower end of the scale in the fair category (38 %). Poor

condition rankings were assigned in parameters of woody debris cover, scour and deposition

features, connectivity, and riparian area. Woody debris recruitment potential for this segment is

very low due to non-forested river banks and a notable lack of woody debris. Connectivity

scored low due to the large dam blocking all aquatic organism passage and due to lack of refuge

areas. The riffle-pool structure was generally weak with minimal pools and very few well-

defined riffles in this segment. The riparian area scored low due to lack of natural buffer and

minimal tree cover in the riparian area.


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a) b)

Figure 4: Stream alteration in T6.06 B includes a) run-of-river impoundment and b) an active

pasture area with instream trampling.

Segment A

This segment begins at the current upstream limit of beaver dam influence, downstream of a

home and barn on the right bank and downstream of the tributary joining from the right. This

segment was segmented because of historic and current beaver activity, and the absence of the

residential encroachments and pasture in segment B.

The downstream reach break was not obvious in the field as the Phase 1 downstream reach break

was placed at the upstream end of a ponded area that no longer exists. According to local

residents the ponding in this area caused by beaver dams is variable. The more natural

downstream reach break would be just upstream of the confluence with T6.5S1.

Beaver dams were present throughout segment A, some of which spanned the width of the

valley. Some dams are currently impounding short portions of the segment or have been recently

breached, while others appear to have breached some time ago and are fully vegetated creating

local floodplain constrictions (Figure 5a). The beaver dams have caused the stream to change

course, traveling along the length of the dam to the breached location. The cycle of beaver dam

building and breaching has increased local inundation and sediment deposition of fines.

This segment is an E (Rosgen) stream type with a gravel bottom and a riffle-pool morphology in

good condition. This segment is in Stage I of the F channel evolution model. There is goodconnection to the broad, flat floodplain that lies between the toe of the steep forested valley wall

on the left and the toe of the Big Hollow Road embankment against the right valley wall. Bank

and floodplain vegetation is primarily thick alders and herbaceous wetland plants.

Segment A has good habitat (RHA score = 73%). The bed substrate cover was scored fair due to

periodic accumulations of fine sediments from breached beaver impoundments.


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a) b)

Figure 5: a) A typical section of T6.06A showing a breached beaver dam on the left in contrast

to b) the narrowly confined section on the right side of Big Hollow Road.

Mid-way along this segment, just upstream of Dugway Lane and a home located in the

floodplain, the channel is diverted to the left side of Big Hollow Road. The channel flows on the

left side of the road for approximately 200 feet, before traveling through another culvert back to

the right side of the road. This portion of the channel is narrowly confined between the steep

right valley wall and the Big Hollow Road embankment (Figure 5b). The channel is wider, very

straight, and takes on plane-bed morphology in this short stretch. Both culverts are fixed

constriction points, with steep riffles forming upstream of each structure. This altered portion of

the channel is not accurately represented on either the USGS topography maps or the Vermont

hydrogaphy data set (Figure 6). The tributary T6.6S1 enters the channel upstream of Dugway

Lane and travels north to the High Knob Brook mainstem before traveling under Big Hollow

Road upstream of Dugway Lane. This flow path was field verified and no channels were found

on the left side of the valley as originally shown in the GIS and topography map.


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Figure 6: Altered channel location in segment T6.06 Aidentified during the assessment.

4.2 T6.05

In Phase 1, the upstream reach break was identified according to mapping as the upstream end of

a ponded area that is no longer present. The upper approximately 250 feet of this reach are

similar to T6.06A, but determined not to be long enough to segment. This 1.2 mile reach has

consistent valley characteristics, but was segmented due to significant differences in channel

condition. The upper half of the reach (Segment B) was historically straightened and has

transported most of its sediment downstream, and the downstream half of the reach (Segment A)

shows has indications of channel migration and fine sediment deposition.

Segment B

Historic straightening occurred over almost the entire segment and sinuosity remains low. The

channel was pushed against the right valley wall near Stokes Hill Road crossing, before the

channel crosses the valley where it was further channelized along the left valley wall. Despite

historic channelization, this channel remains in Good condition. Widening is occurring in some

locations. This segment is in Stage I of the F channel evolution model.


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The corridor has three rural homes along it, with minimal encroachment in the active river

corridor. The Stokes Hill Road culvert is a channel constriction accumulating some sediment

upstream (Figure 7b). The channel runs along a driveway armored with rip-rap and tree

revetments on the valley wall for a few hundred feet. In general a good forested riparian buffer is

maintained.

This segment has Fair habitat condition (RHA = 63%), although it generally scored each

parameter in the low end of the Good category. Local stream widening and historic channel

straightening lowered habitat scores slightly, but overall habitat features were good relative to

anticipated reference condition.

a) b)

Figure 7: a) Typical T6.05B cross-section and b) Stokes Hill Road culvert, looking downstream.

Segment A

This segment begins just downstream of the last home in this reach, and downstream of the

historically straightened stretch of river. This segment is migrating through its floodplain and has

multiple flood chutes, avulsions, and braided areas (Figure 8). There is a large increase in

depositional features compared to the upstream segment including many mid-channel and island

bars. This segment is moderately incised (IR = 1.4) and more entrenched (ER = 1.4) than the

upstream segment, indicating a C to B stream type departure. The observed widening and

aggradation may be caused by instabilities in stream planform from upstream channelization.

This segment is in Poor condition and in stage III of the F channel evolution model.

There is an increase in large woody debris retention on segment A, not seen upstream. This may

be due to the forested floodplains in this segment, but also due to importation of wood from

forested upstream segment B. T6.06 has a wet meadow floodplain, not naturally contributing

LWD to the channel. This is the first segment with a high potential to receive LWD from

upstream sources. The increase in sediment deposition and LWD may be due to a decrease in

channel slope.


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The overall physical habitat on this segment is in Good condition (RHA = 70%), although

scoring Fair in parameters of Bed Substrate Cover, Scour and Deposition Features, and Channel

Morphology. High levels of embeddedness, fining, and riffle stability index were observed along

with general evidence of sediment mobility and lack of sorting. The riffle-pool pattern was

moderately formed, with small pools, non-uniform riffle spacing, and low percentage of riffle

coverage. Abundant mid-channel accumulation was observed. The high incision ratio contributes

to a low channel morphology score.

a) b)

Figure 8: a) Looking downstream at a typical widened section along T6.05A and b) looking

upstream at a flood chute.

4.3 T6.04

T6.04 is a transitional reach, where the valley width and confinement changes from upstream

conditions. This reach was divided into two segments. Segment B, in the upper section of the

reach, has a locally confining terrace on the left bank blocking access to the broader floodplain.

This segment has experienced some incision and is classified as a B type departure from the

reference C due to moderate entrenchment. Segment A is located in a broad flat floodplain,

historically straightened, and is classified as an E type channel due to its low width to depth

ratio. Segment A was defined as a sub-reach of the overall C reference type reach.

Segment B

This segment parallels Big Hollow Road that is located between 50 and 250 feet to the right of

the channel over the entire segment. The stream passes by two homes, flows under Brown Hill

Road, jogs away from Big Hollow road and ends just before a sharp turn at the top of a pasture.

This segment has a very wide valley width, but is confined by a terrace on the left for most of its

length. The existing stream type has been identified as B4 riffle-pool due to moderate width to

depth ratio (W/D = 14.7) and moderate entrenchment (ER = 1.7). This is a departure from the


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reference condition of C. This reach has experienced some incision (IR = 1.8). Stream condition

has been determined to be Fair and in the channel evolution stage II of the F model. The physical

habitat condition was scored as Good (RHA = 83%). Habitat parameters all were in good or

reference condition with no major departure from reference condition.

Encroachments include the road embankment of Big Hollow Road on the right traveling the

entire length of the segment, two constrictions at crossings, and two homes on the left. The

channel in proximity to each of the two homes has a decreased buffer and appears to have been

straightened in the past. Channel dimensions tend to be narrower than reference conditions, than

in these locally encroached and straightened areas. One private driveway bridge and the Brown

Hill Road culvert are both fixed channel constrictions. A local resident reported that there may

be a water quality issue related to waste from kennels at 1127 Big Hollow Road located at the

upstream end of the reach. The presence of a small kennel facility was confirmed, yet water

quality was not investigated as part of this assessment. A tractor crossing exists at the

downstream end of the segment B.

a) b)

Figure 9: a) T6.04 segment B looking downstream with B channel characteristics and b)

segment A looking downstream with E channel characteristics.

Segment A

Just before the channel takes a 90 degree turn to the left, the channel flows around the end of a

confining terrace and into the much wider valley. The channel narrows from a bankfull width of18 feet to 13 feet, the width to depth ratio decreases, and the entrenchment ratio dramatically

increases from 1.7 to 21.6. This downstream segment has reference characteristics of an E type

channel and was designated as a sub-reach of T6.04 which has a C type reference. This segment

is in Good channel condition in Stage I of the F channel evolution model. The physical habitat is

in Fair overall condition (RHA = 62%), although most parameters scored Good. The adjoining


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pasture on the left and lack of forest vegetation, refuge, connected wetlands and seeps decrease

habitat value, as does the presence of some unstable soft sediments.

This segment has a broad flat floodplain on the left comprised of fallow pasture. Historically the

channel was pushed against a tall confining terrace in the right overbank to allow for the

agriculture. The right wooded terrace slope is very tall (>20 feet) and exposed areas are made up

of cobble and boulder size material. The terrace slopes up approximately 100 feet to where it is

bordered by another broad flat pasture. The channel has a relatively low sinuosity near the base

of the confining terrace. This channel has maintained its reference condition of the E channel

after straightening due to the low valley slope. There is no development or encroachment along

segment A.

4.4 T6.03

T6.03 varied in sinuosity, riparian buffer cover, and channel dimensions leading to segmentation.Upstream segment B exhibits E reference condition in an otherwise C reference reach due to

high sinuosity, low width to depth ratio, and channel shape. Segment A is wider, with higher

width to depth ratio, less sinuosity, and generally more consistent with the C reach reference

type.

Segment B

This segment has high sinuosity relative to the straightened condition of upstream T6.04 A,

although channel dimensions remain similar to the upstream segment. This segment is classified

as a sub-reach because the channel exhibits reference conditions of an E4 riffle-pool stream typeand the reference for the rest of the reach is C. The channel is in Good condition and appears to

be in Stage I of the F channel evolution model, with no major adjustment occurring. Overall

physical habitat is Good (RHA = 68%), with major departures in Bed Substrate Cover due to

high fining and riffle stability index and left riparian area due to reduced buffer width and tree

canopy.

This segment has a steep narrow wooded riparian buffer on the right side and an inactive pasture

on the left. This segment may have been historically straightened between the agricultural fields.

Some evidence of lateral migration was observed as the stream increases sinuosity, in the form of

erosion on the outside of meander bends (Figure 10). There are very few encroachments in this

segment. A tractor crossing exists in the segment.


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a) b)

Figure 10: a) A typical riffle section and b) typical meander bend on T6.03B.

Segment A

This segment is wider than the upstream E type channel and maintains the reference stream type

of C riffle-pool. This segment is in fair condition and in stage III of the F channel evolution

model. Sinuosity is moderate, lower than the upstream segment, and there is little evidence of

lateral migration. The upstream half of the segment has a narrow wooded buffer and inactive

pasture in the right overbank and a deciduous forest in the left overbank. The downstream

corridor contains a mature coniferous forest. There are signs of old pastures on the right, as well

as disposed waste (old cars, refrigerators, etc.) near and in the channel. There are no permanent

encroachments in segment A.

The overall physical habitat condition is good (RHA = 74) and similar to the segment B

upstream. This segment has reference LWD, connectivity, and river bank condition. Increased

fining and riffle stability index negatively affect bed substrate cover condition. The pasture on

the right has minimal forested buffer, decreasing riparian area condition.

The very broad valley begins to narrow in this segment, ultimately ending at a confined valley at

the downstream end of this segment. Bedrock grade control is present. The outcropping is

catching fine gravel and causing local widening of the channel (Figure 11b).


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a) b)

Figure 11: Looking upstream in segment T6.03A at both a) a typical riffle section and b)

widened, aggrading section near downstream end of segment.

4.5 T6.02

This reach is in a confined valley and ends with a bedrock gorge. T6.02 was segmented into two

parts. Segment B, at the upstream end of the reach exhibits typical B type channel characteristics

and a step-pool morphology. Segment A is a steep bedrock gorge.

Segment B

The valley abruptly narrows at the top of T6.02, with abundant exposed bedrock in the channel

and valley walls. The valley width is 1 to 1.5 times the channel width, with very little available

floodplain (Figure 12a). The channel is in reference condition (B4 stream type), and has a well-

formed step-pool morphology. The entrenchment ratio measured at the typical cross section is

low (ER = 1.3) for a typical B channel (1.4 < ER < 2.2), but within the acceptable error range (+

or 0.2). Although no floodplain was present at the typical cross section, floodplain widths of 5

to 10 feet were measured in other locations. This segment is in reference stream condition and in

Stage I of the D channel evolution model or may not evolve according to typical models due to

constraints from bedrock.

A mature coniferous forest borders the channel on both sides with a steep, wide, and

unencroached buffer. The only man-made encroachment in this segment is the remains of an old

dam sitting on the left bank (Figure 12b).

Overall physical habitat is in good condition (RHA = 74%). Multiple bedrock grade controls

were present in the segment, affecting connectivity at low flows by possibly blocking aquatic

species. There is also a general lack of refuge at both low and high flows.


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a) b)

Figure 12: Looking upstream in segment T6.02B at a) a typical section and b) old dam remains

on left bank near upstream end of reach.

Segment A

The downstream portion of T6.02 is a bedrock gorge. Geomorphic measurements were not taken

in this segment due to its non-alluvial nature. This segment is very steep and fully confined in

bedrock. There are 5 large drops, a long natural flume section, and multiple cascades in this

segment (Figure 13). Natural bedrock channel constrictions were measured to be as narrow as 5

feet wide in multiple locations. Bed elevation drops at waterfalls were measured to be up to 9

feet tall. These large drops are assumed to naturally limit aquatic organism movement under

most flow conditions. No man-made encroachments existed in this segment and riparian buffer

condition is excellent buffer.

a) b)

Figure 13: Looking upstream in segment T6.02A at a) one of the five large drops and b) a

natural bedrock flume section.


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4.6 T6.01

This reach begins at the downstream end of the bedrock gorge and continues to the confluence

with Lewis Creek. This is a steep reach, with an average channel slope of 3.1%. The channel has

a Cb riffle-pool morphology for the majority of the reach (Figure 14). This is the likely reference

condition of this reach based on valley characteristics and thus a change from the B step-pool

stream type assigned during the Phase 1 assessment. The channel is in Stage I of the D channel

evolution model.

The channel generally has a broad confinement with a wooded floodplain accessible at higher

flows. Multiple bedrock outcroppings are present in the reach, providing vertical and horizontal

grade control. Two short sections of bedrock gorge are present; each less than 500 feet long

(Figure 15). These locations have locally higher slope and are more confined.

The overall physical habitat is good (RHA = 67%). Due to the reachs unencroached nature,most habitat features were in reference or good condition. The bed substrate condition is

compromised of high values of embeddedness, fining, and riffle stability index, and major

evidence of sediment mobility and lack of sorting was noted. The bedrock gorge sections may

influence aquatic organism passage at low flows.

a) b)

Figure 14: a) A typical broadly confined cross section along T6.01 compared to b) a more

narrowly confined portion with bedrock control.


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Figure 15: Valley walls and bedrock constricted area locations along T6.01.

This reach has few encroachments, likely due to low development density and difficult access

down steep valley walls. A quarry near the top of the reach on the right side has recentlyexpanded (as noted based on comparison of footprint in 2003 aerial photographs, Figure 15).

Active work was occurring at the top of the tall steeply sloping right bank for a few hundred feet

along the reach. The work was at least 100 feet from the channels edge and the intervening

wooded buffer was maintained for that distance, with silt fencing installed near the top of the

bank.

The crossings at both Freedom Acres (private road) and VT Route 116 both constrict the channel

(Figure 16). A large sediment bar has formed directly upstream of the Freedom Acres culvert.

This structure is located at a break in channel slope downstream of a bedrock constriction and is

thus prone to sediment deposition.

The VT Route 116 culvert is at the base of a very tall road embankment completely filling the

floodplain. This culvert is undersized and sediment appears to be eroding the concrete slab

bottom. This culvert likely limits aquatic organism passage due to its long length, small size

compared to channel bankfull width, and small outlet drop.


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19

a) b)

Figure 16: The bankfull width and floodplain are constricted in T6.01 by both a) Freedom Acres

and b) VT Route 116 culverts.

4.7 T6.31S.01

This tributary of High Knob Brook is locally referred to as High Knob Brook leading to

confusion when talking to local residents about the area streams. This tributary starts just

downstream of the crossing with Brown Hill Road and ends just upstream of the agricultural

field before flowing into High Knob Brook near the top of reach T6.03. The landowners mother

reported that this stream dries up whenever it doesnt rain for a month, and is typically dry in

August and September. Large ice flows were also reported that covered the adjacent right

floodplain carrying lots of gravel onto the farm field.

The channel is a Cb gravel bed riffle-pool stream, as identified in the Phase 1. The channel is in

Fair condition due to the widespread degradation occurring. It is in Stage III of the F evolution

model. The gravel bed appears to be made up of remaining parts of eroded glacial till that has

come from the banks following the historic relocation of the channel to the left valley edge. The

channel was likely moved to facilitate floodplain agriculture. A short berm runs along the right

side of the channel mid-reach that is non-cohesive and eroding in spots. The channel is relatively

straight, has excessive sediment deposition (i.e., thick bed sediment and large bars) bars, and

eroding banks as it attempts to regain sinuosity (Figure 17 b).

The current left bank and floodplain vegetation at the valley toe is a dense mixed forest, with one

home inside the very wide buffer. The right floodplain is very wide and flat and was until thisyear covered with 21,000 Christmas trees. Recently the soil was amended and seeded with

alfalfa, clover and timothy. There is a narrow strip of trees on the right bank varying between 0

and 100 feet wide.

The overall physical habitat of this reach is fair (56%), indicating a major departure from

reference habitat condition. Bed substrate condition is reduced due to high embeddedness, high


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20

fining, high riffle stability index, and observed unstable, unsorted soft sediments. Scour and

deposition features had a moderately defined riffle-pool pattern, yet pools are small, have no

cover, and are being filled with sediment. Riffles are poorly formed and spaced close together.

Extensive channel alterations due to the straightening and berming decreased habitat condition.

The right side near bank and buffer vegetation is limited.

a) b)

Figure17: Aggradation in T6.3S1.01 is evident a) at mid-channel bars and b) a large side bar.

The crossing at Brown Hill Road is an undersized culvert collecting sediment upstream and

causing scour downstream (Figure 18 a). This culvert appears to have stopped the movement of a

likely headcut that traveled up the channel. The private driveway bridge located mid-reach is not

a channel constriction and appears to provides ample conveyance for water, sediment, and

debris.

The downstream extent T6.3S1.01 identified in the Phase 1 work is at the beginning of the

agricultural field rather than at the confluence with High Knob Brook. Downstream of the reach

break, the channel is a deep narrow channel with E type characteristics (Figure 18b). A meadow

floodplain exists and the bank and buffer vegetation change to primarily herbaceous pasture

grasses and perennials. Bank texture also changed, to a deep silt and sand layer, with a gravel

near the bottom of the bank. This material and channel characteristics are similar to T6.03B and

T6.04A, also located in a broad, flat meadow floodplain. It is hypothesized that this may be the

reference condition of T6.3S1.01, instead of the steeper C channel identified in the Phase 1 and

verified in the Phase 2.


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21

a) b)

Figure 18: a) The Brown Hill Road crossing upstream of the T6.3S1.01 and b) the section of

channel between the downstream end of the reach and the confluence with High Knob Brook.

5.0 Summary of Results5.1 Geomorphic Results Summary

The RGA was not completed for two segments; T6.06 C due to wetland conditions and T6.02 A

because it is a bedrock gorge. Reference condition of segments were verified or adjusted to be

either E or C type channels with riffle-pool morphology, except for T6.02, a steeper B type

channel exhibiting step-pool structure (Table 1).

The channel is typically in good geomorphic condition and in the first stage of the F evolution

model, indicative of a stable channel in many locations. All assessed reaches have gravel bed

substrate. C and E type gravel bed channels in good condition have high sensitivity to changedue to stressors, while B channels in good condition have moderate sensitivity (tend to be more

stable).

The stream starts in wetland conditions in T6.06 C. The channel is an E type channel and travels

through a low gradient wide wetland floodplain to the downstream end of T6.06. T6.06 B and A

maintain their reference stream type and are in fair and good condition.


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22

The valley steepens with a C reference stream type as it enters a forested floodplain at the top of

T6.05. It maintains reference stream type in good condition for T6.05 B, but departs to a B

channel type in segments T6.05 A and T6.04 B due to local confinement and straightening.

T6.05 A is in poor condition exhibiting widening and aggradation. T6.04 A is currently

degrading and in fair condition. The departed condition of these segments increases stream

sensitivity to stressors from moderate to high.

Moving downstream the valley then returns to a lower gradient and widens. T6.04 A and T6.03

B have E reference types and are both designated as sub-reaches. The valley slope then

increases, and T6.03 A maintains its reference stream type of C. The valley then narrows

significantly confining T6.02 B leading to a B type channel in reference condition. This segment

is in stage I of the D evolution model due to bedrock control and has only moderate stream

sensitivity. The stream passes through the bedrock gorge in T6.02 A. T6.01 is a C type channel

with sections of bedrock control and in stage I of the D evolution model or will not evolveaccording to a typical model.

T6.3S1.01 is in fair condition and is degrading, but has not departed from its reference stream

type. It is currently in stage III of the F channel evolution model. It has very high stream

sensitivity.

Reaches along High Knob Brook generally exhibit high stream sensitivity. Exceptions include

the bedrock controlled T6.02 B with a moderate sensitivity and T6.06B, T6.03A, andT6.3S1.01

with very high sensitivity.


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Table 1: Summary of Representative Stream Geomorphic Assessment Data.

ReachLength

(feet)

Entrenchment

Ratio

Incision

Ratio

Width

to

DepthRatio

Reference

Stream

Type

Existing

Stream

Type

Sub-

reach

RGA

Score

Process

T6.06 C 1918 - - - Wetland

Not

Assessed N/A N/A

T6.06 B 3677 5.6 1.2 12.61 E4 R-P E4 R-P 0.56 none

T6.06 A 2887 16.25 1 12.07 E4 R-P E4 R-P 0.8 none

T6.05 B 2378 4.12 1.09 29 C4 R-P C4 R-P 0.66 none

T6.05 A 3858 1.43 1.36 21.5 C4 R-P B4 R-P 0.26

widening

and

aggrading

T6.04 B 2263 1.66 1.81 14.86 C4 R-P B4 R-P 0.64 degrading

T6.04 A 644 21.58 1 10.82 E4 R-P E4 R-P yes 0.75 aggrading

T6.03 B 1370 2.31 1.29 10.9 E4 R-P E4 R-P yes 0.675 none

T6.03 A 2068 2.62 1.25 14.54 C4 R-P C4 R-P 0.71 none

T.602 B 1094 1.27 1.06 15.35 B4 S-P B4 S-P 0.91 none

T6.02 A 760 - - -

Bedrock

Gorge

Not

Assessed N/A N/A

T6.01 5649 6.84 1.06 20.46 C4 R-P C4 R-P 0.88 none

T6.3S1.01 1586 2.5 1.31 12.54 C4b R-P C4b R-P 0.56 degrading


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24

5.2 Habitat Results Summary

Assessed stream segments were identified to have good to fair overall physical habitat

conditions, with no streams having exceptionally poor or reference habitat (Table 2).

Large woody debris condition is adequate, although not in reference condition except for

T6.05A. T6.06 has naturally low amounts of LWD which not only affected LWD locally, but

failed to provide wood to downstream reaches. Fallow agricultural land adjacent to T6.3S1.01,

T6.04, and T6.03 also contributed to reduced input of LWD. Retention of LWD was reduced for

the step-pool stream in T6.02 and was possibly affected by limited upstream inputs.

River bank and riparian area condition were mostly in reference or good condition due to the

rural nature of much of the project area. T6.06 B has reduced bank and riparian area conditiondue to animal grazing in the stream and corridor. The river banks and riparian areas had limited

vegetation on the left side of T6.04 A and T6.03 B. The right floodplain of T6.3S1.01 is

currently pasture. The right buffer of T6.03A is narrow and adjacent to pasture.

Bed substrate cover was found to be in good to fair condition across assessed reaches. Many

reaches had evidence of sediment mobility, moderate to high embeddedness, and / or increased

fining, but sedimentation was not causing a severe departure from reference conditions. T6.02 A

and T6.05 B appear to be sediment transport reaches. T6.3S1.01 has significant amounts of

unstable sediments that are soft underfoot, as well as high values of embeddedness and fining.

Dense algae growth was not observed in the project area except in the pond on segment T6.06B.

Scour and deposition features were generally good across the project area, with well defined

riffle-pool pattern (step-pool pattern in T6.02 A) and sufficient distribution, density, and size of

bed features. In many locations pools were shallow, which is a function of both small overall

stream size and sedimentation occurring in much of the project area. Bed feature quality was

reduced in T6.06 B and T6.3S1.01, the two segments with the greatest, most recent alteration and

encroachment.

Hydrologic characteristics were in reference or good condition in all assessed areas. Although in

good condition, this parameter was ranked lower in T6.06 B due to flow regulation at the run-of-

river dam, T6.01 due to amount of exposed substrate, and in T6.05 B and T6.3S1.01 from

absence or alteration of wetlands and seeps.

Connectivity was generally high across the project area, except for blockages of aquatic

organism passage including a private dam in T6.06B and large natural bedrock controls in T6.02


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25

B. Refuge was often lacking or limited at either low or high flow conditions over the assessed

area. The stated presence of intermittent stream was not confirmed during this assessment, but is

likely influencing connectivity.

Planning recommendations for each individual assessed segment are provided in Section 6.0

based on these results.


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Table 2: Reach Habitat Assessment Summary.

Reach ID

Segment

ID WoodyDebrisCover

BedSubstrateCover

ScourandDepositionFe

atures

ChannelMorphology

HydrologicCharacteristics

Connectivity

RiverBanks,Left

RiverBanks,Right

RiparianArea,

Left

RiparianArea,

Right

Total

Score

(out of

160)

Total

Score

(Percent)

T6.06 C - - - - - - - - - - - -

T6.06 B 3 8 5 13 13 3 5 5 3 2 60 38

T6.06 A 12 8 13 17 17 16 9 9 8 8 117 73

T6.05 B 11 12 11 10 13 13 7 7 8 8 100 63 T6.05 A 19 8 9 10 15 13 9 9 10 10 112 70

T6.04 B 13 11 13 13 16 15 9 9 7 7 113 83

T6.04 A 11 11 11 15 15 12 3 9 3 9 99 62

T6.03 B 12 10 15 14 18 11 6 9 4 9 108 68

T6.03 A 16 9 14 15 14 19 9 9 10 4 119 74

T6.02 B 11 15 14 17 15 8 9 9 10 10 118 74

T6.02 A - - - - - - - - - - - -

T6.01 - 15 8 13 16 13 13 8 8 9 9 112 70

T6.3S1.01 - 16 6 6 8 13 13 8 5 9 3 87 55


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27

5.3 Bridge and Culvert Assessments

All of the structures along High Knob Brook are undersized (Table 3, Appendix B) as indicated

by structure width well under the stream bankfull width. The structures assessed along High

Knob Brook are significant channel constrictions and many are disrupting sediment transport.

The driveway culvert in T6.06 C is the greatest constriction and was ponding water upstream

when assessed. The culverts under Route 116 and at Freedom Acres Road are both severely

undersized leading to upstream sediment aggradation. Each of these structures is likely limiting

aquatic organism passage. The structure on the unnamed tributary to High Knob Brook is

adequately sized with no obvious effects on stream processes.

Table 3: Summary of Bridge and Culvert dimensions measured as part of the Bridge and Culvert

Assessment.

Crossing

Location

Reach

Location

Crossing

Type

Clearance

Height

(feet)

Width

Across

Stream

(feet)

Length

Along

Stream

(feet)

Measured

Channel

Width

(feet)

Percent

Bankfull

Width

(%)

3382 Big Hollow

Road Driveway T6.06C Culvert 1.5 1.5 38 9 17

Private Path T6.06B Culvert 3 3 15 7.7 39

Big Hollow Road -

U/S of Dugway

Road T6.06A Culvert 4 5 40 11 45

Big Hollow Road -D/S of Dugway

Road T6.06A Culvert 3.5 5.5 40 11 50

Stokes Hill Road T6.05 Culvert 6 8 30 16 50

1127 Big Hollow

Road Driveway T6.04 Bridge 4 11 11 17.5 63

Brown Hill Road T6.04 Culvert 6 9 38 17.5 51

Freedom Acres T6.01 Culvert 6.9 9.7 46 22 44

Vermont Route

116 T6.01 Culvert 7 6 85 25 24

Brown Hill Road

Driveway T6.3S1.01 Bridge 6.2 24 10 15 160


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28

6.0 Habitat RecommendationsThis section contains preliminary recommendations for habitat improvement projects based on

habitat and geomorphic assessment data. These recommendations are broad scale and mark a

preliminary step in the creation of planning guidance including habitat features.

6.1 T6.06

Segment C

The RHA was not fully applicable to this segment due to the absence of a defined channel. A

private driveway culvert is undersized creating a severe constriction to flow and sediment

transport, and blocking aquatic organism passage. Retrofit or replacement should be explored at

this structure.

Segment B

Segment B has fair habitat (RHA score = 38%), indicating a major departure from reference

habitat conditions. Poor condition rankings were assigned in parameters of woody debris cover,

scour and deposition features, connectivity, and riparian area. Specific habitat deficiencies noted

include:

Low woody debris recruitment potential and retention; Increases in sediment with major evidence of sediment mobility and lack of sorting; Large dam blocking aquatic organism passage; Lack of refuge areas; Riffle-pool structure is generally weak with minimal pools and few well defined riffles;

and

Riparian area lacks buffer and minimal tree cover in the riparian area.The following recommendations would improve habitat condition over segment B.

Work with landowners to keep animals out of stream. Protect riparian lands to allow return to natural vegetation and sediment filtering. Protect river corridor to give the channel space to establish a natural pattern and natural

processes of flood inundation, sediment transport, and debris transport.

Explore upgrade of undersized culverts to improve connectivity and sediment/debristransport.

Consider alternatives at residential pond to naturalize water quality and sediment/debristransport.

Monitor water quality up- and downstream of pond in summer to explore impairment.


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29

Segment A

Segment A has good habitat (RHA score = 73%), indicative of a minor departure from reference

condition. The following habitat deficiencies were identified during the assessment:

Low woody debris recruitment potential resulting in no debris jams; Periodic accumulations of fine sediments from breached beaver impoundments; Bank canopy is open with very few trees near bank or in buffer; and Channel straightening and diversion through two culverts under Big Hollow Road

removed all habitat features in section.

The low woody debris recruitment potential is likely due to the natural vegetation condition of

the reach, mainly comprised of alders and herbaceous wetland plants. No action is recommended

to increase woody debris or trees in the near bank or buffer areas. More woody debris would be

incident on the project site if upstream culverts and dam were allowed to pass debris to this

segment.

Periodic accumulation of fine sediments is a natural condition associated with beaver dam

building and breaching cycles. Fine sediment storage does not appear to be impairing habitat on

this segment likely due to the ability for this segment to periodically flood and clean out local

substrate sending fines downstream.

Recommendations for segment A follow.

Explore possible return of channel to historic location at the left side of valley instead ofconfining along Big Hollow Road.

Protect river corridor from future development.6.2 T6.05

Segment B

Segment B has fair habitat (RHA = 63%) each parameter generally scored in the low end of the

Good category. There is a minor departure from reference habitat conditions. The following

specific habitat deficiencies were identified during the assessment:

Absence of debris jams; Moderate riffle-pool pattern with small pools and poorly formed riffles; and Stream widening and historic channel straightening.

The absence of debris jams is primarily due to unforested upstream segments and action within

this segment is not recommended to directly change this feature.


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30

Recommendations for segment B follow.

Protect river corridor to give the channel space to establish a natural pattern and naturalprocesses of flood inundation, sediment transport, and debris transport.

Explore upgrade of undersized Stokes Hill Road culvert to improve connectivity andsediment/debris transport.

Segment A

The physical habitat is good in segment A (RHA = 70%), indicating a minor departure from

reference conditions. Reduced habitat quality is evident by altered Bed Substrate Cover, Scour

and Deposition Features, and Channel Morphology. The following were identified as specific

habitat deficiencies:

Increase in sediment deposition and mobility; Riffle-pool pattern is moderately formed, with small pools, non-uniform riffle spacing,

and low percentage of riffle coverage;

Abundant mid-channel sediment accumulation; High incision ratio indicates a reduction in floodplain access; and Limited low and high flow refuge.

Recommendations for segment A follow.

Protect river corridor from future development to allow continued adjustment towardequilibrium.

6.3 T6.04

Segment B

The physical habitat in segment B is in Good condition (RHA = 83%). The following specific

variables have been identified as habitat deficiencies:

Small pool size; High fining and RSI indicating an increase in fine sediment; Incision has decreased access to floodplain; and River corridor development and infrastructure is common.

The following recommendations would increase habitat quality in segment B.

Protect the river channel in proximity to each of the two homes to increase natural buffersand allow creation of a more natural planform.

Protect existing naturally vegetated buffers. Protect the river corridor to allow for new floodplain creation to improve habitat/water

quality and establish sediment/nutrient attenuation areas.


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31

Segment A

Segment A physical habitat is in fair condition (RHA = 62%), although most parameters scored

Good. The overall habitat condition is a major departure from reference condition. The following

have been specifically identified as habitat deficiencies:

Debris jams are absent; Sediments are unstable, unsorted and soft underfoot; Large depositional features and abundant mid-channel accumulation; Pools are generally small, with little cover; Adjacent springs seeps and wetlands are absent or were historically altered; No refuge is present; Major historic straightening occurred; and Left side River Banks and Riparian Area have little tree cover and no buffer from the

pasture.

The following is recommended to improve habitat in segment A:

Protect the river corridor to allow channel to regain sinuosity and establish naturalvegetation.

6.4 T6.03

Segment B

Segment B physical habitat is in good condition (RHA = 68%), although major departures wereseen in the parameters of Bed Substrate Cover and Left Riparian Area. The following specific

habitat deficiencies were identified:

Large woody debris and CPOM were limited; Sedimentation was evident in the parameters of fining and RSI; Refuge was absent; and Left bank canopy and buffer width were reduced.

The following is recommended to improve habitat in segment B:

Protect the river corridor to allow for reestablishment of a wooded buffer and discouragefuture development.


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32

Segment A

Segment A overall physical habitat is in good condition (RHA = 74%). This segment has only a

minor departure from reference habitat conditions. The following specific habitat deficiencies

were identified:

Increased fining and RSI indicating an increase in sediments; and Minimal forested buffer on the right.

Excess sediments are generally caused by grade control at the downstream end of the reach. No

action is recommended to decrease them in the segment.

The following is recommended:

Protect the river corridor to allow for reestablishment of a wooded buffer and discouragefuture development.

Remove debris from river corridor.6.5 T6.02

Segment B

Segment B overall physical habitat is in Good condition (RHA = 74%). The following habitat

deficiencies were identified:

Large woody debris was typically small with few debris jams; Pools were generally small with little cover; Adjacent springs, seeps and wetlands were minimal; Natural bedrock grade control existed in multiple locations blocking aquatic organism

passage;

Lack of refuge at both low and high flows; and Few undercut banks providing cover.

The confined, steep nature of the valley does not provide many locations for adjacent wetlands or

other refuge outside the channel. The grade control affecting aquatic organism passage is

typically small and naturally formed so no action is recommended. Although the large woody

debris was generally small, it was abundant and the riparian areas and buffers are alreadyforested. There were 14 debris jams per mile, which is low for a step-pool channel, but not a

severe departure. No action is recommended to increase large woody debris in this segment.

No action is recommended:


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34

migrate across the valley bottom again. Give the channel space to establish a pattern toreturn towards stable equilibrium and reduce bank erosion and sediment load.

Remove berm on right side of channel to encourage channel to return to valley bottom. Explore active channel restoration to return channel to its historic location. Establish natural floodplain vegetation.

7.0 ReferencesMontgomery, D. R. and J. M. Buffington, 1993. Channel Classification, Prediction of Channel

Response, and Assessment of Channel Condition (Tfw-Sh10-93-002). Timber, Fish, andWildlife Agreement, Department of Natural Resources, Olympia, WA.

Olson, S., 2002. Flow-Frequency Characteristics of Vermont Streams. WRI Report 02-4238.

U.S. Geological Survey in cooperation with the Vermont Agency of Transportation,Pembroke, NH.

Rosgen, D. and L. Silvey, 1996. Applied River Morphology, Wildland Hydrology, Pagosa

Springs, CO.Rosgen, D., L. Silvey, and D. Frantila, 2006. Watershed Assessment of River Stability and

Sediment Supply (WARSSS), Wildland Hydrology, Fort Collins, CO.

Schiff, R., J. S. Clark, G. Alexander, and M. Kline, 2008. The Vermont Agency of Natural

Resources Reach Habitat Assessment (RHA). Prepared by Milone & MacBroom, Inc.with the Vermont Agency of Natural Resources, Departments of Environmental

Conservation and Fish and Wildlife, Waterbury, VT.

SMRC, 2007. Phase 1 Stream Geomorphic Assessment 23 Tributary Reaches, Lewis CreekWatershed, Addison & Chittenden Counties, Vt. Prepared for the Lewis Creek

Association by South Mountain Research and Consulting, Charlotte, VT.

VTANR, 2007. Vermont Stream Geomorphic Assessment Protocol Handbooks: Remote Sensingand Field Surveys Techniques for Conducting Watershed and Reach Level Assessments

(Http://Www.Anr.State.Vt.Us/Dec/Waterq/Rivers/Htm/Rv_Geoassesspro.Htm) .

Acquired via the internet May 17, 2007. Vermont Agency of Natural Resources,

Department of Environmental Conservation, Division of Water Quality, RiverManagement Program, Waterbury, VT.


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Appendix A: Reach Location Maps


40/56

!(

!(

!( !(

!(

!(

!(

!(

STARKSBORO

Big

Holl

ow

Rd

MasonHill

S

Dugway

Ln

StokesHillRd

MasonHillN

RubleeRd

T6.07

T6.06

T4.3S1.02

T6.6S1.02T6.6S1.01

T6.5S1.01

C

B

High Knob Brook T6.061,000 2,000500 Feet

!( Reach Break

!( Segment Break

Phase 2 Valley Walls

Roads

Streams (VHD)


41/56

!(

!(

!(

!(

!(

STARKSBORO

BigH

ollow

Rd

BrownHil

lW

Stokes

HillR

d

MasonH

illS

OutlookWy

T6.06

T6.05

M16S1.05

T6.5S1.01

B

High Knob Brook T6.05500 1,000250 Feet

!( Reach Break

!( Segment Break


Roads

Streams (VHD)


42/56

!(

!(

!(

!(

!(

STARKSBORO

Big

Hollo

wR

d

BrownHillW

T6.05

T6.04

T6.3S1.02

T6.3S1.01

B

High Knob Brook T6.04 and T6.3S1.01250 500125 Feet

!( Reach Break

!( Segment Break


Roads

Streams (VHD)


43/56

!(

!(!(

!(

STARKSBORO

Big

Hollo

wRd

T6.04

T6.03

T6.3S1.01

B

High Knob Brook T6.03250 500125 Feet

!( Reach Break

!( Segment Break


Roads

Streams (VHD)


44/56

!(

!(

!(

STARKSBORO

T6.03

T6.02

B

High Knob Brook T6.02250 500125 Feet

!( Reach Break

!( Segment Break


Roads

Streams (VHD)


45/56

!( !(

!(

STARKSBORO

Route116

TatroRd

FreedomAcres

HiddenAcre

s

AvianLn

BrooksideDr

Bluebird

Ln

Ea

gle Ln

ChickadeeLn

FinchLn

DoveLn

M21

T

T6.01

High Knob Brook T6.01500 1,000250 Feet

!( Reach Break

!( Segment Break


Roads

Streams (VHD)


46/56

36

Appendix B: Bridge and Culvert Assessment Reports


47/56

General Information

SgaID 100005000001191 Local SgaID ---

VOBCIT struct_num

Observers j.clark, m.lyttle Assessment Date 08/20/2008

Town Starksboro Project Name: Lewis Creek

Locationcorner of Dugway Lane and Big HollowRoad

Reach VTID T6.06

Latitude 44.25 Longitude -73.03

Road Name BIG HOLLOW RD Road Type Gravel

Stream Name High Knob Brook High flow stage No

Channel width 11 ft. ( Measured)

Culvert Information

Material Steel Corrugated

Culvert Length 40 ft. Number of culverts 1

Culvert Height 4 ft. Culvert Overflow Pipe No

Culvert Width 5 ft. Skewed to roadway? No

Geomorphic Information

General

Floodplain filled by roadway approaches Entirely

Structure is located at significant break in valley slope No

Culvert slope as compared with channel slope is significantly Same

Upstream

Obstructions at the opening of the structure None

Steep riffle present immediately upstream of structure Yes

If channel avulses, stream will Follow RoadEstimated distance avulsion would follow road 200 ft.

Angle of stream flow approaching structure Mild Bend

Downstream

Water depth in culvert (at outlet) 0.8 ft.

Culvert outlet invert At Grade

Backwater Length (measured from outlet) 0.0 ft.

Outlet drop (invert to water surface) 0.0 ft.

Pool present immediately downstream of structure Yes

Pool Depth at point of streamflow entry 1.2 ft.

Maximum pool depth 1.2 ft.

Downstream bank heights are substantially higher than upstream bankheights

No

More Geomorphic Information

Upstream Downstream In Structure

Dominant Bed Material Cobble Gravel Gravel

Bedrock Present No No

Material Present throughout Yes

Type of Sediment Deposits Mid-channel None None

Elevation of sediment depositsgreater than 1/2 bankfull

Yes No No

Bank Erosion None None

Hard Bank Armoring None None

Stream bed scour causingundermining around or understructure

None None

Beaver Dam near Structure Yes No

Beaver Dam distance (ft.) 200 ---

Vegetation


Dominant Vegetation Type - Left Herbaceous/Grass Road Embankment

Dominant Vegetation Type - Right Road Embankment Deciduous Forest

Does a band of shrub/forest vegetation 50 ft. wide start within 25 ft. of the structure and extend at least 500 ft. up/downstream?

Vegetation Band - Left No No

Vegetation Band - Right No Yes

Wildlife

Roadkill Outside Structure Inside Structure

Species None Beaver - Lodge ---

Other Information

Spatial location data collected withGPS?

No Photos taken? Yes

Comments stream appears to have been diverted across the road in this location for the home to be built

Page Structures | Lewis Creek

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General Information


VOBCIT struct_num



Location just downstream of dugway road Reach VTID T6.06


Road Name BIG HOLLOW RD Road Type Gravel



Culvert Information




Culvert Width 6 ft. Skewed to roadway? Yes


General




Upstream



If channel avulses, stream will Cross Road

Estimated distance avulsion would follow road --- ft.

Angle of stream flow approaching structure Sharp Bend

Downstream



Backwater Length (measured from outlet) 0.0 ft.


Pool present immediately downstream of structure No




No



Dominant Bed Material Cobble Gravel GravelBedrock Present No No

Material Present throughout No

Type of Sediment Deposits None None None


No No No


Hard Bank Armoring Failing Intact


Culvert Culvert

Beaver Dam near Structure No No

Beaver Dam distance (ft.) --- ---

Vegetation


Dominant Vegetation Type - Left Road Embankment Shrub/Sapling

Dominant Vegetation Type - Right Mixed Forest Road Embankment


Vegetation Band - Left No Yes

Vegetation Band - Right Yes No

Wildlife


Species None None None

Other Information


Yes Photos taken? Yes

Comments culvert returning river to correct side of road


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General Information


VOBCIT struct_num



LocationBrown Hill Road off of Big HollowRoad

Reach VTID T6.04


Road Name BROWN HILL W Road Type Gravel



Culvert Information






General




Upstream



If channel avulses, stream will Cross RoadEstimated distance avulsion would follow road --- ft.

Angle of stream flow approaching structure Naturally Straight

Downstream



Backwater Length (measured from outlet) --- ft.






No



Dominant Bed Material Cobble Gravel None

Bedrock Present No No


Type of Sediment Deposits None None None


No No No


Hard Bank Armoring Intact Intact


None None



Vegetation


Dominant Vegetation Type - Left Herbaceous/Grass Herbaceous/Grass

Dominant Vegetation Type - Right Deciduous Forest Deciduous Forest


Vegetation Band - Left No No

Vegetation Band - Right Yes Yes

Wildlife



Other Information



Comments ---


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General Information


VOBCIT struct_num

Observers j.clark, s.pytlik Assessment Date 09/24/2008


Location Private Road - Freedom Acres Reach VTID T6.01


Road Name FREEDOM ACRES Road Type Gravel



Culvert Information

Material Aluminum Corrugated





General



Culvert slope as compared with channel slope is significantly Lower

Upstream





Angle of stream flow approaching structure Naturally Straight

Downstream









No



Dominant Bed Material Gravel Gravel NoneBedrock Present Yes No


Type of Sediment Deposits Side Side None


Yes No No

Bank Erosion Low None

Hard Bank Armoring Intact Intact


None None



Vegetation


Dominant Vegetation Type - Left Mixed Forest Mixed Forest

Dominant Vegetation Type - Right Mixed Forest Mixed Forest


Vegetation Band - Left No Yes

Vegetation Band - Right Yes Yes

Wildlife



Other Information



Comments ---


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General Information


VOBCIT struct_num

Observers j.clark, r.schiff Assessment Date 08/26/2008


Location Stokes Hill Rd off of Big Hollow Rd Reach VTID T6.05


Road Name STOKES HILL RD Road Type Gravel



Culvert Information

Material Metal Pipe





General




Upstream





Angle of stream flow approaching structure Mild Bend

Downstream







Maximum pool depth > 4.0 ft.


Yes



Dominant Bed Material Cobble Cobble NoneBedrock Present No No


Type of Sediment Deposits Side None None


No No No


Hard Bank Armoring Failing Intact


None None



Vegetation


Dominant Vegetation Type - Left Herbaceous/Grass Herbaceous/Grass

Dominant Vegetation Type - Right Road Embankment Deciduous Forest


Vegetation Band - Left Yes Yes

Vegetation Band - Right Yes No

Wildlife



Other Information

Sp

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'Phase 2 Stream Geomorphic Assessment High Knob Brook Watershed', Milone and McBroom, Inc, February...

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