The Benefit of using Geomorphic Principals in Project Design: Case Studies from an Extreme Flood Event in the Poultney and Mettowee Watersheds; Tropical Storm Irene, August 28, 2011

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H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


The Benefit of using Geomorph
ic Principals in Project Design:

Case Studies

f
rom

an Extreme
Flood Event in the P
oultney and Mettowee Watersheds;

Tropi
cal Storm Irene, August 28, 2011


H
ILARY
S
OLOMON
,

W
ATER
Q
UALITY
S
PECIALIST

P
OULTNEY
M
ETTOWEE
N
ATURAL
R
ESOURCES
C
ONSERVATION
D
ISTRICT


Abstract:
The
Poultney Metto
wee Natural Resources
Conservation District (PMNRCD)

is located in
southern Vermont and is
comprised

of lands in the Poultney and Mettowee watersheds, which
drain to the narrow South Lake of Lake Champlain. The District,

with assistance from the
Rutland
Regi
onal Planning Commission (RRPC, Lake Champlain Sea Grant,

and the Vermont Department of
Environme
ntal Conservation (DEC)
,

have conducted Phase 1
Stream

Geomorphology Assessments
(mapping and digital resources with a

quick
field verification) on the entire main stem and many of
the tributaries of the Poultney and Mettowee Rivers.
Additionally, Phase 2
, or field
-
level
assessments, have been conducted on the main stem and select tributaries within these
watersheds.
The goal of these assessments is to understand and promote

long
-
term
stream
stability
,

which

in the Poultney and Mettowee watersheds
,

will l
ead
to decreased phosphorus
transportation to

Lake Champlain
.
Each
geomorphic assessment
posits a number of
predictions
about stream stability and

probable future adjustments

and makes
recom
mendations for

compatible
stream
corridor

projects
and infrastructure management. This study will review
projects that used geomorphic data in their design and evaluate their
ability to withstand the
floodwaters of

Tropical Storm Irene.


Introduction


All streams are undergoing change, some based on the n
atural migration of stream channels
within the context
of their geological setting, while
other changes

are largely a reaction to

land

use
changes

and

human
-
made modifications to

stream channel
s

over the past several hundred years
.
U
nderstanding the
natural

tendency

of

stream
s

to migrate
,

and

predicting changes to

that

migration
process resulting from the influence of past

land

use
changes
,

can provide
valuable
information for future

management decisions

in

stream corridor
s
.



Human activities such a
s
channelizing and berming,

often result in stream
s

that are out of balance
with their surrounding environment. For example
,

straightened sections of stream have higher
slopes and velocities than stream
s

that meander naturally. Bermed sections can hold m
ore water
during floods, which may then break through
the
berm and cause damage in developed areas
. In
both of these examples

the

ultimate

result of human activities in and around the stream
channel

is
increased erosion
, which leads to the mobilization of

sediment and phosphorus to their receiving
waters
.

Stream
s

that are managed for improved stability will result in less long
-
term erosion and
,
in the Poultney and Mettowee watersheds,

contribute less phosphorus to Lake Champlain.


The
study of the
movement of water

o
n the landscape is termed Fluvial Geomorphology.
The
State of Vermont has codified the dat
a collection process for Stream

Geomorphic Assessm
ents

(SGA)
and funded surveys throughout the state.

As a result there is geomorphic assessment
data
availabl
e for all of the

largest streams in Vermont and many of their tributaries.

Within the

H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


Poultney and Mettowee watersheds, the District has assessment data for the Poultney River and
its largest tributaries, the Castleton
R
iver and its tributari
es, the Hubbardton River,

and

the
Mettowee River and its tributarie
s including Flower Brook and

Indian River.


There are several predictive models
built in
to the SGA database that use the data
for each
assessed stream reach

to make predictions about

probab
le future changes the stream may

undergo.
These models predict

stream reach sensitivity to future

landscape

changes or storm
events
, streambed
changes
(lateral or elevational)
that the stream will undergo over time
, and

assign an adjustment process level
(to human changes on the landscape)
to each evaluated stream
segment
.


The geomorphic data results are

used to
help design

appropriate
stream restoration projects,
preserve

critical areas within the

stream corridor

that
maintain stream function and
stability
, and
locate areas sensitive to change that

may threaten valuable infrastructure. Common
recommendations

based on geomorphic assessment data

include increasing riparian buffer width
to increase stream stability; increasing the sizes of bridges an
d culverts to appropriately capture
the flow of water, sediment, and debris carried during storm events, an
d to maintain functioning
flood
plains to capture sediment and decrease
erosion levels

during a flood event.


This

paper will examine several projects

in the Poultney and Mettowee watersheds
that were a
result of recommendations based on the use of geomorphic data
and
examine how they fared
through the

flood event of August

28, 2011,

Tropical Storm Irene.


Tropical Storm Irene


Irene affected the entire Eastern seaboard and reached Hurricane level 3 status over the
Bahamas

before
landing several times in the US
;

in North Carolina, New Jersey, and finally, New York

City
.

Tropical Storm

Irene lingered over Vermont and

droppe
d an average of 5 to
7

inches of rain in
areas where soil moisture levels were already nearly saturated from previous storms

(Master’s
Wunderblog, August 30, 2011)
.
Rainfall across Vermont was highly variable with reported
measurements varying from 3.5 in
ches measured at the Rutland airport to 11.23 inches measured
in nearby Mendon (Weather Underground, historical precipitation data and Master’s Wunderblog,
August 30, 2011).



According to Governor Shumlin, Tropical Storm Irene was the biggest
flood

even
t in over 100 years
in Vermont (Curran, August 30, 2011)
. Over 30 bridges were damaged, including several of
Vermont’s beloved, historic covered bridges (Hallenbeck, August 29, 2011). Many streams were
measured at 100 year flood stage levels and several
news organizations reported 500 year flood
levels in New York State locations (Jonsson, August 29, 2011 and Curran, August 30, 2011).
Weather Underground listed many New England streams that measured record heights on their
USGS hydrographs, including the

Mettowee River

(Master’s Wunderblog
,
August 30, 2011
).


The following graph shows
that the
peak annual discharge for the Mettowee River

during Tropical
Storm Irene
,

16,800 cubic feet per second,

was the highest in

over thirty years of recorded history


H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


and

according to geologist Kristen Underwood, may qualify as a 50
-
year flood event

(USGS, NWIS

and Underwood, personal communication

and recurrence event Mettowee hydrograph
, August,
2012
, provided for the Mettowee Restoration Project Development ERP grant
).




Graph 1: Peak Annual Discharge for the Mettowee River, based on available data for three gaging
stations: North Dorset, near Rupert; Bette’
s Bridge, near Pawlet, and near Middle

Granville.

Stream
discharge recorded for 3/14/1977 and 5/31/1984, were
inferred from measured data at other
locations on the Mettowee River (USGS, NWIS, accessed June, 2012).




Projects Completed in the District


There were several

projects
recently completed in the Poultney and Mettowee watersheds
that
used geomorphic data

in their design. The first were two berm removal projects, one on Gully
Brook, a tributary to the Castleton River
,

and one on the Indian River, a tribu
tary to the Mettowee
River.
Other

project
s

that incorporated geomorphic data

in their design

included

building

a bridge
and

replacing
a
stream crossing

culvert with a larger box culvert
.
The

bridge construction was
located on North Brook, a tributary near the headwaters of the Poultney River, and the

culvert
replacement

was located
on a tributary to
Coggman
Creek, which flows to the Poultney River in
West Haven.


Fin
ally,

several tree planti
ng projects in the District

will increase the vegetated
buffer width along segments of streams in the watershed.


Other projects

based on the results

of geomorphi
c assessments might

include: conserving areas
with

function
ing flood plain access through

conservation easement
s
, cons
erving or restoring

riverine
wetland
s
, and

using geomorphic data to create

Fluvial Erosion Hazard map
s, which help

determine proper buildi
ng

and transportation

set
-
backs along a stream.

The District is interested
in assisting with any project that would increase water quality in the Champlain Basin.





0
2000
4000
6000
8000
10000
12000
14000
16000
18000
Date
3/14/1977
5/31/1984
3/12/1985
3/15/1986
11/27/1986
8/29/1988
5/6/1989
5/13/1990
5/14/1990
11/10/1990
11/11/1990
11/23/1991
3/29/1993
3/30/1993
4/7/1994
4/13/1994
3/8/1995
3/9/1995
1/19/1996
1/20/1996
12/2/1996
1/8/1998
1/24/1999
2/28/2000
12/17/2000
4/15/2002
3/21/2003
3/21/2003
12/24/2003
12/25/2003
3/28/2005
4/3/2005
1/18/2006
1/18/2006
3/15/2007
4/16/2007
3/8/2008
3/9/2008
12/12/2008
12/12/2008
1/25/2010
1/26/2010
8/28/2011
Mettowee River Peak Annual Discharge (ft/sec)

Mettowee north of Dorset
Mettowee near Pawlet
Mettowee near Middle Granville

H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


Gully Brook

Berm Removal

(CA T02.11 and GB T02.11
-
S1.01
-
0)


Gully Brook is a tributary

to the C
astleton River
(at reach T02.11)
with headwaters on

Birdseye
Mountain

in Castleton, Vermont
. As it flows off Birdseye Mountain, it is often

a steep, confined
stream

that

trans
p
ort
s

a lot of

water, sediment, and energy. When Gully Brook

reaches t
he flat
terrac
e to the Castleton River,

it
transitions

from the steep, narrow valley of
its upstream reaches
to the
flat
, ‘very broad’

vall
ey

confinement setting

near the Castleton River,
where it slows
and
deposits

cobble
-

and gravel
-
sized

sediment.
At the project site (on reach T02.11
-
S1.01
-
0) Gully
Brook

was
his
torically
channel
i
zed and bermed

along the flat depositional reach upstream of the
Castleton confluence.
Gravel

d
e
posited al
ong the channel bottom

so heavily and quickly each year
that

durin
g low
-
flow summer months,
stream
w
ater flowed below the surface through

the
interstitial spac
es in the unconsolidated stone layer, creating a section with no surface water. In
addition
, sediment filled the confluence with the Castleton River

causing the C
astleton River to
flood the nearby barnyard and cattle pastu
res of the Traverse Farm, a family
-
run dairy
.


In 2004,
PMNRCD and Vermont DEC’s River Management Program with additional funds and
survey assistance from US Fish and Wildlife, designed a project
that removed the

berm

located on
the eastern bank of Gully Brook as well as

adjacent
fi
ll material to recreate a flood
plain.
The
excavator
s
, Pete Ruby

and Michael Smith
,

also removed material that had built up in the
confluence with the Castleton River.
Several years later this same consortium agreed to remove
several hundred feet of berm along the left

or western

bank of the brook as well
, and again
removed some material at the confluence
.


Gully Brook

now utilizes the newly

accessible floodplain

on a regular basis
.

The
Brook
deposits

much of the sediment

in the floodplain

that, since being channelized in 1959, had

clogged the
confluence and cause
d

water in the Castleton River to back up

and flood the
Traverse
barnyard
.
Additionally,
once the
berms were removed, the natural migration process of the brook

has

transformed
the conf
luence with the Castleton River into

a

sustainable, gently
-
sloping curve
instead of a channelized T.


This post
-
Irene photo (left)

captures

the
Castleton River flowing
freely t
hrough the

previously backed
-
up section

just upstream of
the

Gully Brook confluence
. The channel
appears to have

appropriate

water

depth
, bed
substrate,

and channel dimensions.
This view is
from the Birdseye Road Bridge. Prior to
completion of t
his project, this section of the
Castleton River was slow, murky, and stagnant
behind the dam of sediment at the Gully Brook
confluence.




H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


A site visit

also reveal
ed

that the new Gully
Brook floodplain worked well through the
flooding of Irene

(photo lef
t)
.

Notice the
deposition of sediment in the new floodplain to
the right of the Brook

(center of photo), above
the water)
.
According to property owner, Bob
Traverse, “Gully Brook did as well as any stream
in Vermont” during Tropical Storm Irene
(personal

communication, July 2012).


Photos by Hilary Solomon, July 2012.




This Google earth aerial photo dated

October 8, 2011
,

shows the Gully B
rook
floodplain and
confluence

with the Castleton River
. After completing the berm
-
removal
project at this site,
Gully

Brook looks more geomorphically

stable.
Notice the curved confluence with
t
he
Castleton River
and the active

use of the new floodplain

indicated by deposition of sediment along the v
-
shaped
area betwee the stream and the road
.
Someday the brook may

regain its

natural sinuosity as
the
channel

migrate
s

into the new floodplain.

One new meander, a flood chute with a

braided
channel is seen in this photo.







H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


Indian River

Berm Removal


The Indian River flows
through West Pawlet
to the Mettowee River in Granville, New York.
Much
of the Indian River upstream of West Pawlet is channelized and bermed
along an

old railroad
grade

(now a rails to trails path)
. In 2007,
Poultney Mett
owee NRCD along with Vermont ANR

Rivers
Management Pr
ogram, USDA, and the Vermont Agency of Agriculture
, worked together to
remove 2000 feet of

berm along one
channelized
section of the river

(reach MNY10T1.07E)
upstream of a beaver pond
. Based on geomor
phic principles, now that the berm has been

removed f
r
om the left

or east

bank

of the river, the

river has

the opportunity to

regain access to
its
floodplain during high water events and eventually increase its sinuosity through this section.

Now
, w
hen the Indian River flo
ods, sediment and nutrients will
acc
umulate in the floodplain

and
be assimilated

by vegetation, instead of flushing to Lake Champlain. The increases

in

floodplain
access will also improve ecological habitat

along the stream banks by increasing the width of the
riparian buffer, improve habit
at in the stream channel
by decreasing sedimentation
,

and reduce
erosion hazards by reducing scour in the channel.

(
Shannon Pytlik,
undated document
Rivers
Management Program, V
ermont
ANR).


Graph 2
:
Indian River channel with former rail road track to
right and the channel constricting berm
to the left

(Pytlik)
.














This photo
(taken by Shannon Pytlik)
shows the
Indian River after the
left bank
berm was
removed.

Shortly after Shannon took this
photo, the area was seeded and shaped into a
filter strip, with assistance from NRCS,
using

C
onservation
R
eserve
P
rogram (CRP)

cost
-
share
funds
.

Aerial photos (Google, 2011) show that
the strea
m is slowly regaining its sinuosity and
that
during
Tropical Storm Irene

flood waters
deposited s
ediment up to 623 feet from the
Indian River channel in the newly
-
accessible
floodplain.

0.0
2.0
4.0
6.0
8.0
10.0
0.00
20.00
40.00
60.00
80.00
100.00
120.00
140.00
160.00
180.00
Height
Length
Indian River Berm
Field

Berm

Channel

Rail Trail


H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


Coggman

Creek

Culvert Replacement


The Town of Benson recently completed a
culvert repla
cement on a tributary to Coggman

Creek
on Park Hill Road
. The old crossing structure consisted of a culvert with a smaller overflow culvert

beside it.
The landowner, farmer Ray Richards
,

reported that
the culvert often backed up and
flooded his cow pasture

(personal communication, August 2012)
. This flooding was not only a
nuisance, but also a source of E. coli
, sediment,

and nutrient contamination for the Poultney River
and Lake Champlain.

The culver
ts were replaced in the fall of 2010 wit
h
a larger box culvert,
5 feet tall and 10 feet wide.

The culvert does

not

appear

wide enough to
measure bankfull
width
plus 20%
,
the State
standard

based on geomorphic principles, which
was implemented in 2010 for

all

new structure
crossings (Borg, personal communication, August
2012)
, but
it
is an improvement over the old
structure.

(The measured bankfull width just
upstream of the culvert was wider than 10 feet,
but
this area

is accessed by cows an
d may not be a

good indicator of

bankfull width. Bankfull width is generally measured in riffles on a
representative section of stream

in good condition.
)
Photo provided by Kristen Underwood.


According to Mr. Richards, since the new culvert has been installed, there

has been no flooding in
his cow pasture and that the culvert had no problem passing the floodwaters generated by
Tropical Storm Irene.


The box culvert cont
ains fish baffles that allow

fish to pass upstream through the culvert more
easily and

also trap

se
diment to provide cover and habitat within the culvert.

With the inclusion of
fish baffles in the culvert, this site should be assessed for a fish habitat restoration and an
exclusion fencing and watering project.


Coggman Creek Tree Planting Project

There have been several tree planting projects in the
District as a result of geomorphic assessments. One
tree planting is pi
ctured here on the north (left)

bank of Coggman

Creek upstream of the
Burr Road
crossing.

This low
-
lying, well
-
connected floodplain is
a
n

ideal location

for a tree planting project. T
he
floodp
l
ain connection will be conserved by allowing
this farmland
to
revert
back
to a riparian forest. T
he
larger pine trees in the foreground are protected

by
wire cages and, more difficult to see in this photo,
smaller hardwood
s are protected by tree tubes.
Photo

by Hilary Solomon, August, 2012.


H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


North Brook

Bridge Construction


North Brook is a small brook (
2.28

mi^2 drainage area) that flows along North S
treet in
Middletown Springs and joins the Poultney River at its confluence in Mineral Springs Park.


There are only
four

crossin
g

structures
along this
brook. One of those structures is a driveway
bridge

located about 1.5 miles up North Street
(
at
0.9
mi
2

watershed size
, reach M15
-
S1.03(B)
)

from
the center of Middletown Springs. The

property
owners hired a
hydrologist who specializes in
geomorphic assessments,
Kristen Underwood, to
measure the bank
full width and recommend an
appropriate

span and

locati
on to place the bridge
(Smid/Solomon, 2006).

At the time of
construction the bankfull width of North Brook
was 21 feet, just upstream of the bridge
, and the
bridge span is

24 feet (this bridge was designed prior to the bankfull plus 20% rule, but is
appro
ximately bankfull plus 14%)

The bridge is pictured (left
) at the height of stream flow during
Tropical Storm Irene, and though the water is high and some erosion of the stream banks occurred
above and below the bridge, the structure passed all of the water

and sediment and suffered no
structural damage.

In addition, the wing walls are still
secure

in the bank and did not receive any
up
-

or downstream scour, a common problem with undersized bridges.


J
ust upstream, a

culvert for a small, but steep,

tributa
ry, which passes under North Street
,

failed during Tropical Storm Irene and washed
out hundreds of feet of the class 3 road. The
culvert
wa
s
over three times
smaller than
the
bankfull

width of approximately 10 feet
. T
he
culvert, while

three

feet
around
originally
, was

much smaller at the inlet and outlet
, with the
upstream end deformed and the downstream
end obstructed due to failing riprap from the
culvert header and footer
.


I
t
plugged

during

the

storm and washed

out
the
road.

This
photo (right)

ta
ke
n during Tropical Storm Irene

shows the tributary to North Brook actively
avulsing and washing out the road. Bedrock sloping
from the left shoulder and running under the
road
bed
helped

to facilitate the loss of road materials, most of which
washed into

N
orth Brook
just downstream of the bridge pictured above.

Photos by Hilary Solomon
, August 28, 2011
.






H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation



The tributary culvert pictured at left

(photo from
Underwood,
October
2010)
, was originally 3 feet round,
but the armoring is failing and
causing
deformation of the opening

(first photo) and blocking the
downstream exit (second photo).
This culvert should be replaced with a
larger culvert size to prevent future
road washouts. Unfortunately, the
waterfall located just upstream of
this culvert
may

p
revent it from
qualifying for
aquatic organism
passage (
AOP
)

culvert replacement
funds

soon to be available in the watershed
.

Photos provided by Kristen Underwood, through the
Aquatic Organism Passage stud
y completed for The Nature Cons
ervancy, Vermont Ch
apter.


Flower Brook
,

Instability in the Headwaters


Flower Brook

is included here because it

will probably be targeted by the 201
2
-
2013 PMNRCD
‘Mettowee Project Prioritization
Grant’ provided through the
Vermont
ANR Ecosystems
Restoration Program (
ERP
). The grant
focuses on using all previously
-
collected data, including
geomorphic assessment data, to inform future projects.

The objective of the grant is to find ten
potential projects in the Mettowee Watershed that will directly improve water quality
in Lake
Champlain.



Flower Brook is a tributary to the M
ettowee River. It begins above

a steep river valley,

flows
through

pasture and farm fields, a residential area, a

mill pond at the center of Pawlet
, under
Mach’s General Store, and finally, behind
severa
l houses on School Street to reach

its confluence
with the Mettowee River. The section of stream between the Lily Hill Road bridge and the
confluence was in
cluded in the
S
outh
M
ountain
R
esearch and
C
onsulting

2005 and 2006

geomorphic assessments (rea
ches 1
-
3 in the 2005 assessment and re
ach 4

(M05
-
S1.04)

in the
2006

assessment). In the assessment report (2007) Kriste
n Underwood notes that there were

‘significant fine sediment sources along valley margins from gullies that have develop
ed on …
tributar
ies.’ She noted

that this stream should have high priority for project implementation and
recommends ‘landowner outreach and reconnaissance to evaluate the driving forces of gully
formation on the tributaries and evaluate the feasibility of possible gully

stabilization techniques
and/or sediment attenuation measures.’



Additionally, a study titled, Management Priority Rankings for the Town of Pawlet, Vermont; using
critical source area mapping, was created by Green Mountain College professor

Dr. John Van
Hoesen and showed

Flower Brook to have several areas of high management priority.



H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


The high sedime
nt loads in Flower Brook appear to be caused by

extreme erosion on the
tributaries and more localized instream channel erosion (also noted in the 2007 geomor
phic
assessment) are noted by Mill Pond owner, Gilbert Mach, wh
o stated that

the Mill Pond is
occasionally dredged due to high sediment loads

causing reduced water capacity (Mach, personal
communication, 2005. The mill pond was dredged in September 2012 a
nd the dam sits with the
wooden slats dismantled at this time)
.


The following is an example of the severity of
erosion on the tributaries to Flower Brook.
D
uring a culvert assessment, completed in 2011
by Kristen Underwood, a driveway culvert (photo
left) was listed as having a height of 5.6 feet and
a width of 7.8 feet in a channel with a bankfull
width of 12.3 feet.
While the culvert was
proportionately la
rger than many measured
during this study, t
he landowner reported that
the channel had moved during a previous flood
(possibly Dec. 2000) and Kristen noted that the
upstream bank erosion was high and the armoring on the culvert was failing. Additionally,
there
was a 3.3 foot drop from the culvert to the downstream channel (Underwood, 2011)
;

a ba
rrier to
fish passage and

a sign of
high energy within the tributary stream channel
.


This photo was

taken

within

days of Irene.
The culvert

washed away

during the storm
,
as did

the side yard and some of the land
supporting the residence. The geomorphic
assessment measured higher
-
than
-
expected
erosion in the headwater tributaries of
Flower Brook and the culvert assessment
suggested that there was local i
nstability at
this site and that the culvert may have been
smaller than optimal for this stream.

Photos
by Kristen Underwood, August and
September

2012.


The
se studies taken together, may

have recommended this site as a potential project site.
Unfortun
ately, the culvert
assessment was not completed prior to

Tropical Storm Irene
, and

the
current ecosystem

restoration grant

was in
the
applic
ation process
.





H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


Sykes
Hollow
Brook

Encroachment


Sykes Hollow Brook is a
nother tr
ibutary to the Mettowee River where the studies completed on
the brook predicted the
potential for future conflict
. The 2007 geomorphic assessment,
completed by Krist
en Underwood, noted

that the culvert

on Sykes

Hollow

Brook Road, just north
of

Neilson
Road,

is undersized for the size of the stream and for its location in an alluv
ial setting.
Kristen also noted that the stream had previously

avulsed at this site and that the

stream showed
‘high erosion potential’ and ‘significant mobilization of sedimen
t to the Mettowee River’.
The
assessment made

several recommendations for land manage
ment along this brook, which
included

restoring sediment attenuation function
by increasing the brook’s access to its floodplain

and refraining from building in the

str
eam

corridor.


This photo (left) shows the brook several days
after

Tropical Storm

Irene. It a
vulsed around
the culvert and flowed over
the road and two
adjoining properties
before returning to the
stream channel. This photo was

taken

from
atop the cu
lvert, where erosion to the bank
opposite the avulsion
occurred
.

During the
flood, backed
-
up

water at the
culvert and
avulsion site was deeper
and slower
than

the
water in

the
rest of the channel
,

causing

water
to briefly lose energy, and sediment was

deposit
ed

in front

of the culvert

opening
.

This
material was removed immediately after the storm and some of this material was then used as a
berm, as seen in this photo. Photo by Kristen Underwood, August 2011.


During the 2010

culvert assessment
, Kris
ten noted

that (after Irene) th
e culvert right bank wing
wall wa
s significantly eroded and outflanked and that the water avulsed to the left bank corridor
and crossed Sykes Hollow Road. The culvert height is 8 feet and the width is 12.7 feet. The
channel

bank full width is 16 feet.





H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation





This

aerial photo (
left,
Google
Earth, October 8, 2011
)
shows the path of the brook

(
as seen
through sediment
deposition)

as it leaves the channel upstream of
the
culvert and flows through two adjacent propertie
s,
eventu
ally returning

to the
previously existing
stream
channel
.



Downs
tream,
inside the confines of its banks, Skyes
Hollow
Brook

washed

out a newly
-
constructed driveway
that

was
built
right
on the stream bank (aerial photo
bottom, to left, October 8, 2011)
.



The final

aerial phot
o

(
bottom right,
October 8, 2011)

shows sediment
deposited

in a farm field

just upstream of
the confluence with the Mettowee River
.

Though much
sediment was deposited in this and other farm fields, t
he
majority of

sediment transported by this brook flowed
into the Mettowee River and eventually Lake Champlain.




















H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


Aftermath

of Irene


Shortly after Tropical Storm Irene, almost every town was rebuilding roads; some towns were
working

to reform stream banks and

put streams back into their pre
-
storm channels after a
significant avulsion. Most of this work was urge
nt and necessary. However, in several situations
landowners

took adva
ntage of this chaotic
period

to benefit their own interests. One

example is
the rail
road company that ditched

two tributari
es to the Castleton River
,

over
digging

the channel

to a deeper,

highly constricted channel cross
-
section. They also dredged

the channel of the
Castleton

River

deeper

into its
bed
.

The result is that the wetland
area
just upstream
from the
dredged section of river significantly decreased. The

following set of
aerial photos show
decreased
water levels in the wetland
.


Google Earth Aerial photo from 2009
, notice
the

wetland upstream
, covered in standing water
.




Google Earth Aerial photo
s

from October 8, 2011, notice

the extent of the wetlands is much
reduced

and the water

mainly

flows through in the deepest part of the channel.







H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


Close up of
the
dredging

along the Castleton River

and on
e of it
s tributaries.





Lake Champlain and other Conclusions


Phosphorus concentrations continue to remain high in Lake Champlain (Ethan Swift, personal
communication, June 2012). In 2009, the US Environmental
Protection Agency revoked Vermont
Department of Environmental Conservation’s (DEC) 2002 Lake Champlain Phosphorus Total
M
a
ximum Daily Load (TMDL), a
study provided for in the Clean Water Act that addresses pollution
loading to a contaminated water body, an
d is currently rewriting that report with the goal of
achieving sustainable phosphorus levels in Lake Champlain.
At this time, every environmental
agency

and many non
-
profits
in V
ermont, New York, and Canada are

working to achieve
sustainable phosphorus l
evels in Lake Champlain.


The goal of the Vermont ANR/DEC’s geomorphic assessment program is to gain long
-
term stability
throughout the river networks in the State, thereby decreasing sediment and nutrient transport to
Lake Champlain from chronically unsta
ble streambeds. Using geomorphic data in project design
and following the recommendations in the geomorphic assessment reports will result in not only
decreasing the amount of sediment and phosphorus to Lake Champlain, but will also decrease the
costs ass
ociated with repairing or replacing compromised infrastructure after storm and flood
events. The projects reviewed in this report that used geomorphic data in their design, withstood
the historic levels of flooding that resulted from Tropical Storm Irene

and prevented some
additional amount of phosphorus from flowing to Lake Champlain.




H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


References


Borg, Jaron,
Vermont DEC River Management Engineer,
personal communication, August 2012


Curran
, John, Helicopters Rush Food, Water to Cut
-
off Vermont Towns,
AP, posted on ABC local
news channel 6, August 30, 2011


Field, John, Poultney
and Hubbardton
River
s

Phase 1 assessment
, 2005


Godfrey
,

Lisa, Poultney River and
Selected
Trib
utarie
s Phase 2

Geomorphic Assessment, December
2006


Goog
le Earth, Aerial Photos,

dated October 8, 2011, copied June 29, 2012 and July 23, 2012


Hallenbeck,
Terri, Vermont’s Covered Bridges Take a Hit from Irene,
Burlin
g
ton Free Press
, staff
writer, August 29, 2011


Homziak, Jurij,

PhD,

University of Vermont and
Lake Champlain
Sea

Grant,
personal
communication, August 2012


Jonsson
, Patrick,

Aftermath of Irene: Budget
-
Straining Clean Up and Lives Turned ‘Upside Down’,
CSM, posted August 29, 2011



Masters, Jeffrey , PhD, Irene’s 1
-
in
-
100 Year Rain Triggers Deadly Flooding, Master’s
Wunderblog,
Weather Underground, August 30, 2012


Masters, Jeffrey, PhD, Irene’s Rains Heaviest on Record in Vermont, Master’s Wunderblog,
Weather Underground, August 30, 012



Reed, Bill,
Middletown Springs Road Commissioner,
personal communication, Augu
st 2011

and
August 2012


Richards, Ray,
landowner and farmer,
personal communication, August 2012


Rosgen, David

and Silvey, Hilton Lee, Applied River Morphology, 2
nd

ed., Wildland Hydrology, 1996


Solomon, Hilary, Poultney Tributaries

P
hase 1
Assessment,
Poultney Mettowee Watershed
Partnership, 2007


Solomon, Hilary, Vail Brook Phase 2 Assessment (with North Brook reach 3 Phase 2 data), Poultney
Mettowee Watershed Partnership, 2007


Traverse, Bob,

landowner and dairy farmer,
personal communication, July
2012



H
ilary Solomon


September 13, 2012


Poultney Metto
wee NRCD


Post
-
Irene Impact Evaluation


Underwood, K.,

Phase 2 Stream Geomorphic Assessment
,
Mettowee River Water
shed, Pawlet,
Rutland County, Vermont
; South Mou
n
tain Research and Consulting, October 2005


Underwood, K.,
Phase 2 S
tream
G
eomorphic
A
ssessment
,

Mett
o
wee River Watershed

Rutlan
d and
Bennington Counties, Vermont,

South Mountain Research and Consulting,
November
2007


Underwood, K.,

Culvert A
quatic
O
rganism
P
assage

Assessment

data
, collected

for T
he
N
ature
C
onservancy
, 2010 and 2011, South Mountain Research and Consulting,
data pr
ovided May 2012


USGS, streamflow data

from NWIS, North Granville Station, Bette’s Bridge Station, near Rupert
Vermont Station, data downloaded June 2012


P
ytli
k, Sh
annon,

Vermont DEC Rivers Management Program, River Scientist,
personal
communication, Augu
st 2012


Pytli
k, Shannon, Indian River Summary Paper,
Vermont ANR Rivers Management Program,
no
date, likely 2007


Van Hoesen, John, PhD.,
Management Priority Rankings fo
r the Town of Pawlet, Vermont; Using
Critical Source A
rea

M
apping
, Green Mountain
College Geology Dep
ar
t
ment
, 2011


Weather Underground, www.wunderground.com, historical
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data
, accessed August 2012