Connecticut River Basin Program
Phase II
Water Quality Impact Evaluations on Flood Protection
Measures for The Connecticut River Supplemental Study
United States Environmental Protection Agency
Region* I
May, 1975
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FOREWARD
Phase II of the Connecticut River Supplemental Study is
the evaluation of alternative measures for reducing flood damages.
Phase II attempts to assess the performance of alternative flood-
management systems against environmental, economic, flood-damage re-
duction, social, and organizational/institutional criteria.
The water quality impact evaluation report is one portion of
the environmental assessment on the performance of the flood management
systems. Other inputs on the environmental aspects will come from the
Bureau of Outdoor Recreation, U.S. Fish and Wildlife Service and the
National Park Service.
The water quality evaluations discuss the possible ramifications
that each selected alternative will have on water quality in the
Connecticut River Basin. The discussions consider the effects on the
entire basin and more selectively in the specific area for which the
alternative is considered.
The discussions at this time are generalized, based on the limited
amount of information developed during Phase I of the study. The analyses
were developed to facilitate the selection of the most feasible alternative
plan. Once a plan is determined,a more thorough investigation should
be performed,if necessary, possibly in an Environmental Impact Statement.
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Table of Contents
SUBJECT PAGE
Parameters Used for Water Quality Impact Evaluations 1
Lover Basin Water Quality Impact Evaluations 5
Deerfleld River Water Quality Impact Evaluations 13
Ashuelot River Water Quality Impact Evaluations 20
Beaver Brook 22
Honey Hill Reservoir 25
Non-Structural Measures 33
Both Reservoirs - Honey Hill & Beaver Brook 34
The Sugar River Water Quality Impact Evaluations 35
White River Water Quality Impact Evaluations 45
Ammonoosuc River Water Quality Impact Evaluations 53
Non-Structural Proposal for the Northern Portion of the
Connecticut River Basin 59
Passumpsic River Water Quality Impact Evaluations 62
Victory Proposal 64
Small Watershed Projects:
Bassumpsic River Proposal 72
Mill River Proposal 77
Whetstone Brook Proposal 83
Treatment Costs for Impaired Water Quality at Impoundments 89
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List of Tables
NUMBER PAGE
1 Lower Basin Water Quality Impact Evaluation 9
2 Meadow Dam and Reservoir (Statistics) 15
3 Meadow Dam (Impact Evaluations) 17
4 Beaver Brook Dam (Impact Evaluations) 23
5 Honey Hill (Statistics) 28
6 Honey Hill Dam (Impact Evaluations) 31
7 Claremont Dam (Statistics) 36
8 Claremont Proposals (Impact Evaluations) 39
9 Gayesville Reservoir (Statistics) 47
10 Gayesville Proposals (Impact Evaluations) 49
11 Bethlehem Junction Dam (Statistics) 54
12 Bethlehem Junction Proposals 57
13 Non-Structural Proposal for Upper Connecticut
River Basin 61
14 USGS Flow Data on the Moose River taken at
Victory, Vermont in 1968 66
15 Victory Dam (Statistics) 66
16 Victory Proposal (Impact Evaluations) 69
17 Passumpsic River Proposal (Impact Evaluation) 75
18 Flood Plain Land Use (Mill River Watershed) 78
19 Mill River Proposal (Impact Evaluations) 81
20 Whetstone Brool Proposal (Impact Evaluations) 85
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PARAMETERS USED FOR WATER QUALITY IMPACT EVALUATIONS
The water quality impact evaluations have utilized the para-
meters established by the states in their present water quality guide-
lines and other pertinent parameters affecting water use. The
evaluation includes two parts. The first part consists of a matrix
comparing the influences that each alternative exerts on individual
water quality parameters. The matrix has, as column headings, the
parameters listed below:
1. Dissolved Oxygen
2. Sludge Deposits
3. Color and Turbidity
4. Taste and Odor
5. pH
6. Coliform Bacteria
7. Temperature Change
8. Chemical Constituents
9. Radioactivity
10. Nutrients
The matrix also contains a column for additional comments and
parameters relevent to the evaluation, but not necessarily considered in
the states' guidelines on water quality.
The row headings in the matrix list the aspects of each alterna-
tive evaluated and includes, but may not be limited to the following,
should more evaluation be warranted:
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a. Effects on water quality in the area
proper of the proposed impoundment;
b. Effects on water quality below the area
proper of the proposed impoundment;
c. Effects on water quality due to changes in
land use*; and
d. Where applicable, effects on water quality due
to other proposed structures or modification of present
structures or conditions, i.e., dikes or channelization.
For each plan, the evaluator notes the type actions affecting water
quality and enters an evaluation in the matrix.
After completion of the matrix, Part 2 consists of a qualified
narrative explaining the matrix evaluation and other considerations
such as the general areas being affected. The areas affected are those
reaches in which the plan is projected to cause changes in water
quality from projected conditions with no plan.
The changes induced, viewed in terms of water quality standards,
may be either positive or negative and are indicated as follows:
*Note: Changes in land use consider only those changes which are involved
in non-structural flood control measures, i.e., flood plain zoning and
clearing. These changes would discourage further encroachment on the
stream. However, if the zoning permits agricultural use of the flood
plain, this can lead to a major non-point source of pollutants, via the
agricultural runoff. If measures are not taken in the establishment of
zoning regulations to control this runoff, heavy influxes of nutrients
from fertilizers and domestic animal wastes, pesticides, herbicides and
sediments could be experienced. For the purposes of this report, it will
be assumed that zoning will Include restrictions to control agricultural
runoff, otherwise zoning only in developed or structured areas would be
discriminatory and defeating in terms of water quality for a non-
structural program.
2
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Negative Impacts
- Where effects induced on water quality could inhibit
or adversely affect the ambient concentration levels
slightly.
— Where effects induced on water quality could inhibit
or adversely affect ambient concentration levels to
such a degree as to violate the standards set on the
waterbodies classification.
-/— Adverse effects could range from slight to more severe.
In-the more severe instance, standards attainment may
be Inhibited.
-/O Adverse effects are felt to exist, but may be negligible
or readily controllable.
Positive Impacts
+ Where the effects on water quality could enhance
slightly the ambient conditions in the water body.
++ Where the effects on water quality could enhance
ambient conditions to such a degree that higher
classifications can be met.
+/0 Benefits are felt to exist, but minor and easily negated or
influenced by other factors.
0 Conditions remain unaffected.
+/- Could have adverse and/or beneficial effects on water quality.
N/A Not Applicable.
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It is emphasized that the effects described are strictly
those relating to water quality standards; the ecological, scenic,
recreational, and economic aspects would be accounted for elsewhere.
The second part of the individual plan evaluations explains
the rationale used in the matrix evaluation as well as other pertinent
information. All evaluations are based upon information cited or
the contents of the Phase I Report on Water Quality.
After evaluating each local alternative, another matrix could
be used to compare alternative plans proposed for local areas. If
this be the case, the entries in the first columns should describe the
areas affected and the last column should list remarks, necessary
increases or decreases in treatment costs, or appropriate mitigating
measures.
At this point in the investigation, no attempts are made to
determine the best plan from the water quality aspects as the best
plan must be selected from an integrated comparison of all evaluations
from other fields and to do so here, would be premature and could
lend a bias to the final selection process.
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LOWER BASIN WATER QUALITY IMPACT EVALUATIONS
The lower basin impact evaluations for water quality will
cover the following area: the mainstem of the Connecticut River south
of the Deerfield River in Massachusetts.
There are seven major flood damage centers in the lower
basin including Hartford and East Hartford in Connecticut and Spring-
field, West Springfield, Chicopee, Holyoke, and Northampton in
Massachusetts.
For the protection of these seven damage centers the
Supplemental Study proposed three alternative plans:
Alternative 1 - Seven upstream reservoirs plus non-
structural measures.
Alternative 2 - Raise existing dikes and walls plus
non-structural measures.
Alternative 3 - Non-structural measures only.
Associated with these plans are three degrees of non-structural
programs: minimum, moderate and maximum, which are to be used in con-
junction with the plans. Alternative 3 covers various levels of flood
protection that could be provided by strictly non-structural measures
to minimum, moderate and maximum degrees. The selection of the alterna-
tives and the associated degrees of non-structural measures were
determined by the basin states. The Study Management Team, after dis-
cussion with the basin states, concurred on the alternatives to be
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evaluated. Alternatives 1 and 2 are evaluated In conjunction with
minimum and moderate non-structural measures and Alternative 3
is evaluated in conjunction with moderate and maximum non-structural
measures. For further explanation on these measures, reference is
made to the Cheney Miller and Ellis Report for Phase I.
Due to the limitations of the present water quality data,
the three alternatives were evaluated without differentiating the
water quality data through the associated degrees of non-structural
measures. Water quality impacts were qualitatively assessed in terms
of general non-structural measures.
Although the area under consideration in the lower basin
is extensive, none of the seven major damage centers to be protected
are located above or directly below any of the proposed flood control
reservoirs. Hence, the evaluations in Table I, concerning the
effects on water quality in the immediate area of the impoundments
are generalized to include information on all seven proposals collectively.
The individual dams are considered in more detail under individual
evaluations. In addition, the row heading "effects below the Impound-
ment" considers only the water quality effects in the lower basin
areas considerable distances below the impoundments. The areas directly
below the impoundments where the most Immediate effects of the dams
will be felt are also discussed under the individual proposal evaluations.
In the lower basin evaluation, the non-structural programs
considered in Alternative 3 are evaluated Independently of the seven
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flood control reservoirs. Since the land use controls proposed in the
non-structural program for the lower basin act independently in
affecting water quality, and these controls exert no influence on the
water quality near the impoundments, the reservoirs and the land use
controls can be considered justifiably as two separate flood control
measures in this instance.
The three degrees of the non-structural program, applied to
the lower basin will induce different effects on water quality.
Generally, floodproofing will not induce any changes, zoning will
prevent further degradation, and clearing will induce the most signifi-
cant changes in water quality. The evaluations on the effects of land
use around impoundments are evaluated with the individual reservoir
proposals.
Water Quality Impact;
Table 1 indicates the water quality impact evaluations on the
lower basin area taking into account the seven flood control dams, the
elevation of existing dikes, and the non-structural programs.
Individually, the seven flood control dams have certain bene-
fits and disbenefits generally localized in the area of the impoundment
and immediately downstream. In the lower basin area, the effects of
these localized benefits and disbenefits and their respective impacts,
are often dampened. Thus, the water quality impacts determined for
the lower basin area attributed to the seven reservoirs, are minimal.
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The upstream waste discharges and the hydroelectric operations
of the power companies which affect the mainstern flow act as other
minimizing agents on the effects of the seven reservoirs.
However, there are serious water quality concerns associated
with any structural flood management program. One concern is the
amount of flood plain encroachment the proposed plan will induce in
the protected area. Another concern is the effect the proposed structures
will have on the water quality in the immediate area of the structure
itself. The latter concern will be Investigated for each of the
seven proposed reservoirs, and the three watershed proposals sponsored
by the Soil Conservation Service. These three systems are on the
Passumpsic River, the Mill River and the Whetstone Brook. The systems
are usually a series of small impoundments.
Taken collectively, the Impoundments by their nature, will
permit lower dissolved oxygen concentrations in their depths,
stratification and increased surface water temperature. The impound-
ments will prevent the flushing of sludge buildups. Color and
turbidity may increase due to increased algal productivity in the
impoundments. Sediment influx may increase from unstable shorelines
i
as a result of pool level fluctuation. The chemical.and nutrient
concentrations should show slight increases in the impoundment areas,
due to collection in the impoundment basin. This is characteristic of
deeper Impoundments. Taste and odor, and pH levels are thought to be
relatively unaffected. Coliform concentrations will decrease due to
settling allowed in the impoundments and increases in detention time.
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Table 1
Lower Basin Water Quality Impact Evaluation
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Remarks and
Miscellaneous Information
Effects in the area of the
impoundments.
00 +
N/A
Effects collectively are minimal, but the
induced effects at each site are more
severe.
Effects below the
impoundments.
0 00 + 0 + N/A
Less coliforms released because fewer waste-
water treatment plants inoperative due to
flooding. More severe effects if dam
encourages downstream floodplain
encroachment.
Effects as a result of
raising the existing
dike structures.
0 0-/0 0 0000 0 0
Since dikes are already present only dis-
benefit is temporary sedimentation and
siltation from modification of existing
structures unless floodplain encroachment
is encouraged .
Effects due to changes
in land use.
+ + +/- N/A 0 + 0 + N/A +
If clearing is incorporated into program,
buffer strip will enhance water quality
by removing some contaminants from
runoff.
LEGE.IP:
N/A
-/O
Effects could inhibit or adversely affect the ambient concentration levels slightly.
Effects could enhance slightly the ambient conditions in the waterbody.
Conditions remain unaffected.
Could have adverse and/or beneficial effects.
Not applicable.
Adverse effects are felt to exist, but may be negligible or readily controllable.
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Dissolved oxygen concentrations, nutrient concentrations
and sludge deposits may be unfavorably affected downstream because
the impoundments reduce the peak flows which tend to flush organic
buildups from the stream bed. These sludge deposits exert an
oxygen demand and release nutrients to the system. However, the
dissolved oxygen concentrations could also be slightly enhanced by
augmentation during low flow periods from the impoundments if
proper procedures are used in releasing the Impounded water to
prevent it from being oxygen deficient. Conforms concentrations
are thought to be reduced because flood damages to treatment plants
in the basin will be reduced by the proposal. Some nutrients and
oxygen demand will be removed by operating treatment plants, but due to
the amounts received by the stream from other sources and the degree
of treatment at the plants, the net effects of the treatment plant
protection in reducing these parameters would be small. Chemical
concentrations will be slightly diluted by the augmented flows from
the reservoirs. These augmented flows may be more significant in the
lower basin where the migration of the salt water wedge from Long Island
Sound is dependent upon the amount of fresh-water being discharged to
the Sound. However, the presence of hydroelectric dams in the basin
and the stronger, overriding influence of tidal fluctuations will
minimize the impacts on the seasonal salt water migration.
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Color, turbidity, pH, taste and odor conditions, and
temperature are relatively unaffected in the lower basin by the
impoundments.
The dike alterations will have the least effect on water
quality in the lower basin. However, if raising the dikes encourages
more flood plain encroachment, then the present water quality
problems associated with floodplain encroachment will increase.
Land use changes will have the most positive impacts on
water quality in the lower basin area. The significance of these
impacts is determined by the extent of land use controls. As stated,
if the controls are merely floodproofing of existing buildings, then
the water quality of the lower basin will remain unchanged. However,
when land use controls include clearance of structures, developmental
controls, and restrictive uses of the flood plain, greater impacts on
water quality occur. If a buffer strip of land (reference in Phase I)
is reserved for flood damage reduction, then it can be used for water
quality enhancement, provided it remains as open space and is not
covered to a large extent by asphalt or other impervious surfaces. By
using a buffer strip to absorb the runoff from the urbanized areas,
many of the contaminants in storm water runoff can be effectively
removed. Thus, land use controls could enhance the levels of dissolved
oxygen and reduce sludge buildup, color and turbidity, coliforms,
chemicals, nutrients and other stormwater runoff cpntaminants.
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During the initial clearing phases, turbidity may be
adversely affected by the increased silt and sedimentation usually
associated with construction and demolition sites. The effects of
this are generally short-term and can be mitigated by pxeventative
measures.
Naturally, the larger the buffering strip left between
the river and the urban centers, the greater the assimilation potential.
The amount of contaminant assimilation also depends on the distribution
of the runoff across the buffer strip. If runoff is allowed to cut
directly through the strip in a channel, natural or man-made, the
contaminant removal will be greatly decreased.
Summary;
Alternative 1, the seven upstream reservoirs plus non-structural
measures, has the greatest number of negative water quality impacts.
However, the water quality impact effects on the lower basin are minimal.
Those effects In the vicinity of the impoundments are more significant
unless the Impoundments encourage further floodplain encroachment in
the lower basin. If encroachment is encouraged, water quality impacts
on the lower basin would be much more severe.
Alternative 2, raising existing dikes and walls plus non-
structural measures, generally has no effect on water quality in the
lower basin unless it encourages floodplain encroachment in which
case the alternative would induce negative effects.
Alternative 3, non-structural measures only, has the greatest
number of positive impacts on water quality in the lower basin area.
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DEERFIELD RIVER WATER QUALITY IMPACT EVALUATIONS
Background;
The Meadow Dam would be located on the Deerfleld River about
9.0 miles upstream from its confluence with the Connecticut River, or
1.4 miles upstream from Stillwater Bridge in the Towns of Deerfield
and Conway, Massachusetts. The reservoir would extend into the Towns
of Buckland and Shelburne and terminate at the lower extremities of
Shelbume Falls Village.
The Meadow Reservoir would be the largest in the 23-reservoir
Connecticut River flood control system. It would be a single purpose
flood control project and would have no winter pool. The project
would provide minor land-oriented recreation facilities. Normal
operation of the reservoir would occur during spring runoff and
possibly in the late summer or early fall when hurricane flooding is
a threat. Based on a hydrologic analysis from the Corps of Engineers,
the frequency of the reservoir reaching spillway crest elevation 396 has
been calculated to occur about once in 50 years.
Two existing hydroelectric dams located along the Deerfield
River within the reservoir area would be removed. They are the Western
Mass. Electric, Gardner Falls Dam and the New England Power Company,
Dam No. 2. One other New England Power Company, Dam No. 3, located in
Shelburne Falls, would continue to operate until such time that a flood
of major magnitude would require utilization of storage beyond damage
stage at this power station.
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Two short stretches of local roads would be relocated. The
Bardswell Ferry Bridge-, would probably be inundated for a few days each
year and the existing track of the Boston and Maine Railroad would be
relocated along the southern periphery of the proposed reservoir
As mentioned, the project would be operated as a single pur-
pose flood control reservoir and normally would be kept empty except
during freshet periods or other periods of abnormally high runoff.
The dam would be used to store portions of the peak flood discharge of
the Deerfield River and would release this storage when the threat of
flooding had subsided.
Estimated land acquisition amounts to about 1,900 acres at
spillway crest, of which 250 acres is productive dairy land and apple
orchards. This 250 acres is located and divided about equally between
the Towns of Conway and Shelburne. About 50 acres of open land would
be purchased in Buckland and Deerfield. The balance of the acreage
totalling about 1,650 acres is heavily wooded except tha.t approximately
15% is devoted to waterway area. There are 27 homes which would be
purchased and removed. This number is equally divided among Buckland,
Shelburne and Conway. The Town of Deerfield has no improvements
involved.
At the time the proposal was drafted, there was no treatment
facility in the Town of Buckland. The treatment plant has now been
constructed and in operation. The outfall for the plant is at an
elevation of 366 feet and the influent enters at 375 feet. Based on the
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following information provided by the Corps of Engineers, the
frequency of flooding for this treatment plant is about every
20 years (Table 2).
Table 2
Meadow Dam and Reservoir
Frequency Versus Acreage - Frequency of Occurance
Years
1
2
5
10
20
35
50
/Runoff/
Inches
1.5
2.0
3.5
4.5
5.5
7
8
Acres
520
680
980
1,180
1,380
1,700
1,900
Elevation
275
295
330
350
365
385
396
The flood level at the treatment plant for the 1938 flood of
record was 352.3 feet without the reservoir. Hence, the placement of
this reservoir will require that the plant either be moved or protected
by a dike and pumping system. Connected with this plant is a sewer sytem
which may also require moving or reinforcement.
Water Quality Impact;
Table 3 indicates the water quality evaluations performed for
the Meadow Dam Proposal. The river segment considered for temporary
impoundment is classified "B" but grades into "C" classifications after
the confluence with the Green River tributary.
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Since the dam has no permanent pool and is essentially a
flow through structure, the water quality in the area of the impound-
ment is thought to remain relatively unaffected except for possible
increases in turbidity and sedimentation.
Most of the reservoir area is located in a steep portion of
the river valley. Thus, water allowed to back up during times of dam
operation will cause a relatively small lateral displacement of flood-
waters. However, due to the steepness of the slopes and the periodic
inundation, the remaining vegetation and cohesive nature of the soils
may be undermined, resulting in increased erosion. The eroded sediment
would be carried downstream causing increases in turbidity and
sedimentation both above and below the dam site.
With the dam's operation, the flushing of oxygen demanding
sediment by peak flows will be reduced. By reducing the high flows,
the Meadow Dam could inhibit the attainment of present standards in the
lower portions of the Deerfield River below the dam. Since the Green
River tributary contributes a significant amount of contaminated water
to the lower Deerfield, these peak flows may be necessary to remove
sludge buildups which would exert oxygen demands on the already
taxed water system. However, with the discharge and treatment deadlines
established in the Federal Water Pollution Control Act Amendments of
1972, the sludge loads and oxygen demands should be reduced and thus
possibly reduce the need for this flushing action.
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Table 3
Meadow Dam
Considerations
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Remarks and
Miscellaneous Information
Effects on water quality in
area above dam.
0 0 0 0 N/A
Increase in sedimentation due to possibly
unstable shorelines, no effect on coli-
forms unless treatment plant is not
relocated or protected.
Effects on water quality
below the dam to con-
fluence with Conn. River.
0 0 N/A
More protection to Hownstream treatment
plants. Might have less oxygen de-
manding sludge removal as a result of
the decreased flushing action of
floodwaters.
Effects on water quality due -/O -/O -/O -/O -/O -/O -/O -/O M/A -/O
to changes in land use.
Designed for flood control only. Thus, it
will not encourage development around dam
site area above it. Topography also in-
hibits development. Only has land use
disbenefits if it encourages floodplain
encroachment downstream.
LEGEND:
- Effects could inhibit or adversely affect the ambient concentration levels slightly.
+ Effects could enhance slightly the ambient conditions in the water body.
0 Conditions remain unaffected.
N/A Not applicable.
-/— Adverse effects could range from slight to more severe. In the more severe instance,
standards attainment may be inhibited.
-/O Adverse effects are felt to exist, but may be negligible or readily controllable.
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The waste treatment plants will not be subject to inoperative
periods as a result of flooding, if the Meadow Dam is constructed. With
the protection afforded to these downstream plants by the dam, the amounts
of coliform concentrations should be reduced. Some nutrients and oxygen
demand will be removed by operating treatment plants, but due to the
amounts received by the stream from other sources and the degree of
treatment at the plants, the net effects of the treatment plant protection
in reducing these parameters would be small.
Developmental pressures are not anticipated for this area as
a result of the impoundment. Topographical conditions will continue
to discourage development. Hence, there should be no changes occurring
in water quality as a result of land use changes induced by the proposal.
Treatment and discharge elimination requirements under the 1972 Amendments
will lead to a better water quality by eliminating existing upstream
discharges. However, there will be adverse effects on water quality if
the dam encourages flood plain encroachment downstream and flood plain
management is ignored.
Summary;
The Meadow Dam has very little effect on water quality in the
area immediately above the dam. Adverse effects in this area relating
to dissolved oxygen concentrations, sludge buildups and erosion and
sedimentation are thought to be slight. The downstream effects will be
more significant due to the amount of flood flow reduction this dam
offers and the amount of contaminants entering the lower Deerfield from
urban runoff and the Green River.
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Compliance with the 1972 Water Pollution Control Amendments
will somewhat mitigate these conditions and reduce the dam's impacts
on water quality in the lower portion of the Deerfield River.
Since the dam will do nothing to encourage development above
the dam site, it is felt that water quality will remain relatively
unchanged due to land use. However, adverse conditions would occur
if the dam encouraged flood plain encroachment downstream.
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ASHUELOT RIVER WATER QUALITY IMPACT EVAULATIONS
Background:
Topographically, Keene is bisected by a large, flat plain
which divides the City into eastern and western segments. Through
this plain flows the Ashuelot River and several tributaries which
join it in this reach. The Ashuelot, a major tributary of the
Connecticut River, rises in Sullivan County and joins the Connecticut
River at river mile 139.8 in Hinsdale, New Hampshire. The river
meanders through the City of Keene, where it is joined by the Branch.
The Branch is formed by the confluence of Otter Brook, flowing from the
mountainous terrain to the east of the plain, and Minnewawa Brook.
Beaver Brook, which flows north to south through the heavily developed
areas of the City, joins the Branch just above its confluence with the
Ashuelot River. The Branch joins the Ashuelot River 1.6 miles below
Faulkner and Colony Dam, and 0.4 miles above the Keene-Swanzey boundary.
Flowing from the hills to the west is the Black Brook-Ash Swamp Brook
system, Joining the Ashuelot just south of the Swanzey boundary. On
three sides of the flat, bisecting plain in Keene are steeply-sloped
wooded hills. It is on these steep slopes that the tributaries to the
Ashuelot originate.
The steep hills surrounding Keene form a bowl-like structure
with Keene at the bottom. Because of this bowl-like topography, there
is essentially one large flood plain in Keene. The most critical flood
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damage area is the 1.6 miles of the Ashuelot River upstream of the
Branch confluence. Here, the river meanders and has a low discharge
capacity because of its small cross-sectional area and flat gradient.
The result is that considerable ponding occurs, and areas remain
inundated for several days during flood events.
There are two Corps of Engineers flood control dams
operating in th/s Ashuelot River watershed. Surry Mountain Lake is
located on the Ashuelot River, 5 miles north of Keene. Otter Brook
Lake is located on Otter Brook about 4.9 miles above the confluence
of the Branch with the Ashuelot River. The area inundated along the
Ashuelot River by flooding is approximately 3,000-3,500 acres. The
total flood prone areas represents about 14.7 percent of the City.
Following the 1973 flood, the City of Keene is seriously
considering a proposal prepared by Camp, Dresser and McKee, Consulting
Firm, which recommends 3,850 linear feet of channel improvements from
Baker Street to Harrison Street, replacement of the Myrtle and Water
Street Bridges, reduction of the stress on the Railroad Bridge, and
removal of the small bridge below Water Street. The proposal also
recommends the reconstruction of Baker and Marlboro Street Bridges.
The City hopes that these measures will reduce the severity of flood
stages associated with storms of the December 1973 magnitude.
Alternatives considered:
Four major alternatives for reducing flood damage in the
Ashuelot River Basin have been developed. These are: 1) non-structural
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flood damage reduction measures only; 2) the construction of Beaver
Brook Reservoir only, plus non-structural measures; 3) the construc-
tion of Honey Hill Reservoir only, plus non-structural measures;
4) the construction of both reservoirs, plus non-structural measures.
Water Quality Impact:
Beaver Brook Reservoir;
The Beaver Brook project is located in the City of Keene and
the Town of Gilsum, Cheshire County, New Hampshire, 2.5 miles upstream
(north) of Keene. The dam controls 6 of the 10 square miles of drainage
area associated with Beaver Brook.
The dam is designed for recreation and water supply uses. The
permanent recreation pool will be 36 feet deep and cover 203 acres
until the water supply benefits are utilized. Then the water contact
aspects of recreation will probably be curtailed, and the pool depth
will fluctuate depending on the water supply demands. Accordingly, the
pool may be lowered to a depth of 10 to 17 feet.
Because of its size and location, the Beaver Brook proposal is
actually a local protection project whose principal beneficiary is the
City of Keene. The proposal will have minimal flood control effects
downstream on the Ashuelot River. Table 4 contains the water quality
impact evaluations for the Beaver Brook Proposal. The impacts in the
area of the impoundment are thought to be very slight. There may be a
decrease in dissolved oxygen and an increase in temperature due to the
physical properties associated with the impoundment. There may be some
22
-------
Table 4
Beaver Brook Dam
Considerations
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Remarks and
Miscellaneous Information
Effects on water quality in
area of impoundment.
-/O 0 00 +
0 N/A -/O DO and temp, adversely effected by impound-
ment behavior; coliforms settle out.
Sludge and nutrients may accumulate in
impoundment from organic detritus decom-
position, but effects slight.
Effects on water quality
below the impoundment.
-/O -/O 0 000
0 N/A -/O DO, temp, and nutrients may be adversely
affected slightly due to impoundment
releases downstream.
Effects on water quality
due to changes in land
use.
-/O -/O -/O -/O 0 -/O -/O -/O N/A -/O
Adverse effects if summer camps are
allowed to encroach the area. This
is doubtful , however, since the area
is slated as a water supply. Land use
effects are felt to be very slight.
LEGEND:
Effects could inhibit or adversely affect the ambient concentration levels slightly.
+ Effects could enhance slightly the ambient conditions in the water body.
0 Conditions remain unaffected.
N/A Not applicable.
-/O Adverse effects are felt to exist, but may be negligible or readily controlled.
-------
slight sludge buildup behind the dam due to the decay of organic
detritus material which may become trapped behind the impoundment.
Coliforms will be reduced as a result of settling and nutrients
may increase slightly as a result of their release from any decomposed
organic material which becomes entrapped in the impoundment. All
other parameters are thought to be unaffected.
Below the impoundment, the effects of the proposal are also
thought to be slight. There may be some slight temporary reduction in
dissolved oxygen due to demands made by impoundment releases on the
ambient dissolved oxygen concentrations downstream.
The temperature of the downstream water may be elevated if
warmer water is released from the impoundment. Since the flow peaks
will be moderated by the impoundment, sludge accumulations from the
urban runoff of Keene may not be flushed from the stream during times
of high flow. If this happens, a higher local oxygen demand may be
exerted below the impoundment. Some slight increase in downstream
nutrient concentrations may be noticed if the released impoundment
water should contain higher nutrient concentrations.
Beaver Brook is classified "B", with the initial use of the
Beaver Brook Reservoir being recreation and long term use being water
supply. Consequently, land use controls around the impoundment are
imperative. If summer home encroachment is allowed around the
reservoir, the possibility of poor septic systems, poorly maintained
roads and shoreline instability due to wave action generated from power
-------
boats may impair water quality enough to prevent its use for water
supply without expensive treatment requirements. Proper management
and land use planning directed toward preserving this area for
future water supply will insure that the usage of this impoundment
for recreation will not impair water quality.
Summary;
The effects of the Beaver Brook Proposal on water quality will
be very slight if not negligible in the area of the impoundment and
downstream.
Land development around the impoundment if properly controlled
should have no adverse effects on the future use of the impoundment as
a water supply for the City of Keene. However, if sound land manage-
ment is not practiced, water quality within the impoundment could
degrade as a result of development. This degradation could preclude
the impoundment's use as a water supply unless more expensive treatment
was utilized.
Honey Hill Reservoir;
The Honey Hill Dam will be located in the Town of Swanzey,
New Hampshire, about one mile west of East Swanzey on the South Branch
of the Ashuelot River about 5.5 miles above its confluence with the
Ashuelot River. At full pool elevation, the reservoir would extend
upstream into the Town of Richmond.
25
-------
Honey Hill would be a multiple-purpose project for flood
control and recreation. Other uses, such as low flow augmentation for
fish and wildlife enhancement, and for improving the water quality of
the stream are being considered. However, according to the Federal
Water Pollution Control Act, augmentation cannot be substituted for
waste treatment as a method of attaining water quality standards. This
requirement was followed by the Coordinating Committee and they assigned
water quality benefits as an after treatment consideration. Possible
industrial water supply on a seasonal usage for the industrial complex
located between Winchester and Hinsdale, New Hampshire is also being
considered. The dam would provide control from the upstream tributaries
of the South Branch of the Ashuelot River. In so doing, it would enable
the slower discharges around the Keene-Swanzey municipalities to recede
to an acceptable level before new releases are added that would, other-
wise, aggravate the flood problem in these municipal areas.
During the summer months, 15 June to 15 September, a pool
would provide for recreational pursuits. A 3-foot summer drawdown would
provide flow releases of 15 cfs (cubic feet per second) from storage to
augment the extremely low summer flows of the Ashuelot River. Flows would
be augmented by 26 cfs in the fall in anticipation of winter-spring floods
and to possibly further enhance the downstream fishery. These releases
would continue until the reservoir reached the winter pool elevation.
Additional flows would be released, if necessary, to assure that the
26
-------
pool had receded to the winter pool level by the first of December,
and this level would be maintained through the winter. The recrea-
tion pool would be restored in the spring by impounding the spring
runoff after the threat of flooding had passed. The summer
recreation pool would be restored by the middle of June.
The reservoir area lies in a wide open valley with gentle
sloping hills abutting the dam site. In the southerly portion of the
impoundment, the Franconia Mountain Range rises steeply to altitudes
of over 1,300 feet, msl. The surrounding land is mostly wooded and
rolling with some rugged terrain and open areas.
Real estate acquisition would include the outright purchase
of 2,070 acres in the dam and dike sites, work areas, and the
reservoir area to spillway crest elevation 524 feet, msl, and an
additional 300 foot horizontal reservoir buffer zone. 590 acres would
be purchased in the buffer zone and the remaining 1,480 acres would
be needed for the dam and reservoir area. 1,950 acres would be located
in the Town of Swanzey with the remaining in the Town of Richmond.
About one-half of the land to be acquired is woodland, another
40% is classified as open or agricultural land. The remaining acreage
is equally divided among residential and industrial developments,
roadways and waterways. Outright purchase of improvements within
project boundaries would also be required. At Honey Hill, this would
involve the purchase of some 42 residences, 5 farms, 2 commercial and
2 industrial developments.
27
-------
Normally al'.l lands and improvements within a 300-foot buffer
zone around the perimeter of the reservoir above spillway crest would
be purchased outright. Exceptions to this real estate acquisition
policy may be made in certain cases, such as highly developed areas.
State Route 32 would be relocated a total of 1.6 miles and
improved a total of 2.3 miles along the easterly perimeter of the
reservoir. In addition, 4.5 miles of local roads would be relocated
and 1.0 mile would be improved.
According to Table 5 prepared by the Corps of Engineers, the
Honey Hill Reservoir will have an annual pool depth varying from 30 feet
during the winter months to 38 feet during the summer recreational
months and a spillway crest depth of 51 feet. Flow release from
June 15 to Sept. 15 is 26 cfs and that from Sept. 15 to Dec. 1 is
43 cfs. Included in the flow release figures are the natural inflows of
11 cfs and 17 cfs, respectively.
Table 5
Honey Hill Dam and Reservoir
Item
Stream Bed
Winter Pool
15 June Pool
15 Sept Pool
Spillway Crest
Elev.
473+
503
511
508
524
Pool
Depth
0
30'
38'
35'
51'
Acres
0
680
970
860
1,460
A.F.
0
9,100
15,800
13,000
31,500
28
-------
Present water quality classifications for the Ashuelot
River range from"BMto"c"with some tributaries having "A" classifica-
tions. The portion of the Ashuelot classified "C" is approximately
the first ten miles of the river above its confluence with the
Connecticut. This is due to numerous discharges containing municipal,
paper and leather wastes. The Honey Hill Reservoir on the South
Branch of the Ashuelot is in a class "B" river segment.
Table 6 indicates the water quality impact evaluations per-
formed for the Honey Hill proposal.
Since the pool depth maintained will be at least 30 feet, the
impoundment will be subject to the effects of thermal stratification
and overturn. Due to the major amount of agricultural land in the
drainage area supplying the reservoir, the runoff will contain higher
nutrient concentrations than would normally occur. This nutrient influx
may induce algal problems in the reservoir. As a .consequence of thermal
stratification and this nutrient influx, water quality problems in the
reservoir may be more significant. Dissolved oxygen concentrations will
possibly be deficient in the hypolimnion. Sludge buildups and increases
in turbidity will increase depending on the amount of primary produc-
tivity. The impoundment will permit the coliforms to settle, resulting
in reduced concentrations. The temperature will be elevated in the
surface layers by insolation. Chemical concentrations in the impound-
ment will depend on the amount used on the crops and carried in by
agricultural runoff. Decomposition in the hypolimnion may also
29
-------
cause an increase in chemicals especially if the process becomes
anaerobic. Nutrient concentrations will depend on the amount
carried in by the runoff and the extent of primary productivity
in the reservoir.
Below the impoundment, adverse effects may be felt on the
dissolved oxygen content and the temperature due to the possible
release of oxygen deficient water and/or warmer surface water from
the impoundment. By removing the peaks from the flood flows, the
effective flushing of sludge deposits which may buildup from the
downstream waste discharges (listed in Appendix D of the Comprehensive
Report) may be eliminated. If sludge does accumulate, it will exert
an increased oxygen demand on the stream. Downstream nutrient concen-
trations may increase if the released water has a higher nutrient
content.
With augmented flow, the effects of the oxygen demands, color,
turbidity, chemicals, coliforms and nutrients attributed to the down-
stream waste discharges may be ameliorated. However, in no case can
low flow augmentation be substituted for the treatment requirements
proposed in the 1972 Amendments.
Flow release is also important during the period of reservoir
construction and filling. Adequate flow releases must be maintained
so that water quality downstream is not impaired by wastes which would
be discharged to the stream. Flow rates must be sufficient enough
to assimilate these wastes safely. Coliform concentrations will also
30
-------
Table *
Honey Hill Dam
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Considerations Q o
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Remarks and
Miscellaneous Information
Effects on water quality in
area of impoundment.
00 +
N/A
Stratification adversely effects temp, and
DO. Agricultural runoff increases nutri-
ent and chemical influx. This may lead
to increased primary productivity and
turbidity. Pool fluctuation could in-
crease sedimentation.
Effects on water quality
below the impoundment.
+ 00 + - + N/A +/-
Effects on water quality due
to changes in land use.
N/A' 0 - 0 - N/A
DO and temp may be adversely effected by re-
leases from impoundment. Color, turbidity
& chemical concentrations downstream diluted
by low flow releases. Coliform concentra-
tions reduced by protected treatment plants
Care must be taken on reservoir filline
so as to provide adequate flow.
Due to the proximity of Swanzey Lake and
Metropolitan Boston, this area may be
subjected to heavy summer home develop-
ment and recreational demands which will
place stress on water quality. Control
over summer home development is needed.
LEGEND:
N/A
Effects could inhibit or adversely affect the ambient concentration levels slightly.
Effects could enhance slightly the ambient conditions in the water body.
Conditions remain unaffected.
Could have adverse and/or beneficial effects.
Not applicable.
-------
be reduced as a result of the treatment plant protection afforded
by the reservoir, but the reduction in oxygen demand and nutrients
afforded by the plant protection will not be significant in view of the
supplies contributed from outside sources and the degree of treatment
provided at the plants.
Land use around the Honey Hill impoundment may be the most
influencing factor on water quality. Due to the close proximity of
Swanzey Lake, an established recreational area, and the Boston Metro-
politan area, the development potential of the land around the
impoundment will greatly increase. Since the Corps of Engineers land
acquisition policy will not protect the area from an over-development
of summer homes, land management and planning should be used to
restrict the development or encroachment of summer camps along the
reservoir. These summer home developments are often broken down into
the smallest possible lots for monetary purposes and no regard is
given to environmental constraints. Consequently, heavy impacts on
water quality result. Poor connecting roads are subject to erosion
which deposit sediments and increase the turbidity in the impoundment.
Sediments may also increase as a result of pool fluctuation, wave
action and power boats. Septic seepage contributes to increased
nutrients, oxygen demands, coliforms, chemicals, and indirectly to
sludge buildups by increasing primary production. If salt is required
on the roads in the winter, an increase in chemicals, primarily chlorides,
would occur in the runoff to the impoundments.
32
-------
If the area is to be developed for recreation, then the
associated townships should strengthen their zoning to consider
environmental impacts and possible water quality degradation.
Summaryi
Normal changes in water quality which occur as a result of
impoundment may be compounded by a significant amount of agricultural
runoff into the impoundment.
The effects downstream may be slight. If augmented flow
enhances water quality, it can in no way substitute for treatment
required by the 1972 Amendments.
Land use may have the most significant effect on water
quality. If the potential for development around the reservoir is
large then zoning should be encouraged to preserve the aesthetic
and environmental quality of the area as well as the water quality
in the impoundment. Impacts determined are felt to be "guarded"
since heavy uncontrolled development around the impoundment may induce
more severe effects than originally estimated.
Non-structural Measures:
The minimum program of non-structural measures for the Ashuelot
Basin will serve to keep the water quality conditions essentially the
same. The moderate and, moreso, the maximum non-structural programs will
affect water quality to a greater extent, since they involve flood plain
clearing and open space zoning.
33
-------
The impact evaluations for non-structural measures will
be essentially the same as those performed on the lower basin area.
The major exception being that the impacts evaluated will be localized
and pertain to Keene and the Ashuelot River, an area and river of
much smaller magnitude.
Both Reservoirs - Honey Hill and Beaver Brook;
The water quality impact evaluations for this alternative
can be ascertained by combining the impacts determined for each of
the reservoirs separately.
34
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THE SUGAR RIVER WATER QUALITY IMPACT EVALUATIONS
Background;
The Claremont project would control a drainage area of
245 square miles which would make it the third largest in the
recommended flood control reservoir system and the second largest
of those projects yet to be constructed.
The dam site on the Sugar River is 1.5 miles upstream from
the City of Claremont, New Hampshire or 7.1 miles above the confluence
of the Connecticut and Sugar Rivers. The Reservoir at full flood
control pool would extend upstream about 4 miles, lying for the most
part within the municipal boundaries of Claremont with a small portion
lying in the Town of Newport, all in Sullivan County.
The 245 square miles of drainage area are hilly with a few
sharp peaks. At the headwaters of the Sugar River, there are several
ponds.
The summer conservation pool will be approximately 50-feet
deep and be maintained from June 15 until Labor Day, except that a
2-foot drawdown would be allowed during dry periods. A low flow re-
lease of 11 cfs would serve to enhance the downstream fisheries from
Labor Day to the end of the foliage season, about 1 November; otherwise
outflow would be maintained to equal the inflow, resulting in a constant
pool that is 48-feet deep. After 1 November, 8,000 acre-feet would be
released at the rate of 133 cfs lowering the reservoir to the winter pool
35
-------
depth of 36-feet. The winter pool elevation would be reached by
1 December to provide sufficient storage for possible winter-spring
floods. The pool would be refilled for recreational uses by
15 June, depending on the snow pack and spring runoff.
Table 7 indicates the pool level fluctuations on an annual
basis:
Table 7
Claremont Dam and Reservoir
Item
Stream Bed
Winter Pool
15 June Pool
15 Sept. Pool
Spillway Crest
Elev.
530±
566
580
578
638
Pool
:Depth
0'
36'
50'
48'
-108'
Acres
0
- 630
860
830
.U520
A.F.
0
12,000
22.000
20,000
90,400
In the Comprehensive Water and Related Land Resources Investi-
gation - Connecticut River Basin',' a benefit attributed to the reservoir
was for low flow augmentation. It was felt that a summer demand by the
year 1990 for flow augmentation could be met to an extent by the impound-
ment.
The Coordinating Committee for the Comprehensive Study followed
the stipulations in the Federal Water Pollution Control Act which prohibit
using low flow augmentation as a substitute for waste treatment at the
source. Consequently, water quality benefits were assigned conditionally
in that they were considered subsequent to required treatment.
36
-------
At full pool elevation, the reservoir would inundate
1,520 acres of land of which 90 and 10 percent, respectively., is
located in Claremont and Newport, New Hampshire. An additional
2,330 acres of land would be acquired above elevation 638 for
recreational pursuits, such as hiking, camping, nature study, cross-
country skiing and skimobiling. This acreage includes, but is not
limited to, the 300 feet of horizontal land purchased by the Corps
of Engineers for surcharge backup.
A total of 3,850 acres of land would be acquired for the
project. Approximately 51 percent of this total is woodland with
another 46 percent equally divided between tillage and pastureland.
Industrial, commercial and residential developments make up the remain-
ing percentage. There are about 85 improvements of which 79 are
situated below spillway crest elevation 638 feet, msl. Approximately
72 of these improvements are within the Claremont City boundary.
The project would require relocation of 2.9 miles of State
Routes 11 and 103 along the northern periphery of the lower half of
the reservoir. About 1.9 miles of the inundated Unity Pond Road on
the southwesterly side of the reservoir would also be relocated. There
would be no necessity for relocating the remaining roads that would be
within the permanent pool area. Roads leading to the proposed
recreational facilities would require very little improvement.
That portion of the Claremont and Concord Railway Company, a
single track railroad, which lies within the reservoir areas would be
purchased. This railroad provided service from Concord, New Hampshire
37
-------
to Claremont Junction in the past; however, when the Hopkinton-
Everett Flood Control Reservoir was built, a section of this railroad
was purchased in fee. Since then, freight service to other points
leading from Concord to Newport was discontinued but unscheduled
freight service from Claremont Junction to Newport has been maintained.
The total cost of relocating this railroad would be prohibitive and a
negotiated settlement would be attempted.
Presently, the Sugar River has three classifications for
various reaches; "A", "B" and "C". The reach of the Sugar River with
the "C" classification extends from Claremont to the mouth of the
river, a distance of approximately 4 miles. This lower classification
can be attributed to the municipal, paper, textile, and machinery
wastes being dischar5ed in this stretch of the river. The source,
Sunapee Lake, and some small tributaries; Whitewater Brook and Grandy
Brook are assigned "A" classification. The remaining segments of the
Sugar River have "B" classifications.
Water Quality Impact;
Table 8 lists the water quality impact evaluations for the
Sugar River Proposal.
The location of the Claremont Reservoir poses special problems.
Since a major portion of the surrounding land is agricultural, as is
indicated by the amount of tilled and pasture land to be acquired for
the project (46%), the runoff into the impoundment will contain high
38
-------
Table 8
Claremont Proposals
Considerations
T>
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Remarks and
Miscellaneous Information
Effects on water quality
in area of the impoundment
N/A 0 0
u>
vo
Effects on water quality
below the impoundment.
Due to nutrients coming from Newport treat-
ment plants and agricultural runoff,
enrichment will result affecting DO,
sludge, color & turbidity. Chemicals
increase from runoff.
+/- N/A 0 +/0 - +/- N/A
Lower DO, nutrients and possible sludge
accumulations may occur due to controlled
reservoir releases. Adequate flow must
be maintained when reservoir is filling
or water quality may be affected
Effects on water quality
due to changes in land
use around the impoundment.
N/A 0 - 0 - N/A
Summer camps may also cause water quality
degradation by poor roads, septic systems
and summer home over-crowding. Proper
zoning on summer camp development is
Effects of non-structural
proposal for the Sugar
River on water quality.
0 0
0 + N/A +
If clearing is incorporated into the non-
structural program, buffer strip will
enhance water quality be removing some
contaminants from runoff.
LEGEND:
+/0
0
+/-
N/A
-I —
Effects could mhibit or adversely affect the ambient concentration levels slightly
Effects induced could inhibit or adversely affect ambient concentration levels to such a
degree as to violate the standards set by the waterbodies classification
Effects could enhance slightly the ambient conditions in the water body
CBondeiftionsirr'emSn unaffe'ed^ *"" ^ *""* ™*"* °* ^^ » °^ '•«•»•
Could have adverse and/or beneficial effects.
Not applicable.
Adverse effects could range from slight to more severe. In the more severe instance
standards attainment may be inhibited.
-------
concentrations of nutrients. The Town of Newport has two treatment
plants which discharge to the Sugar River. The plants, not designed
for nutrient removal, would discharge into the headwaters of the
proposed reservoir, further adding to the high nutrient influx.
The presence of the treatment plants, in their present form,
above the impoundment will violate present New Hampshire standards on
nutrient discharges to impoundments. Consequently, the Town of Newport
would have to provide tertiary treatment to remove the nutrients.
However, nutrient influxes from the agricultural land alone might be
enough to encourage eutrophication. Consequently, the dissolved oxygen
concentration could go below 75% saturation, and thus violate "B"
standard requirements.
The Claremont Reservoir nutrient situation seems similar to
the situation faced on the Roanoke River at the Smith Mountain Lake
Impoundment in'Virginia. Roanoke*s treatment plant discharges to the
river at the headwaters of the impoundment. Eutrophication formerly
attributed to the treatment plant discharges, has been getting progres-
sively worse. Research by T.J. Grizzard* found that the contributions
from the Roanoke Treatment Plant, although significant, were not solely
responsible for Smith Mountain Lake's eutrophication problem. Even
with the removal of the treatment plant, agricultural runoff would
be enough to continue the present trends. Thus, the situation possibly
*Grizzard, T.J. - Thesis Research - Department of Sanitary Engineering,
Virginia Polytechnic Institute and State University, unpublished (1973),
40
-------
faced at Claremont may not be improved by advanced waste treatment
alone. The situation around the proposed Reservoir would induce
sludge buildups, increased turbidity and chemical concentrations,
also. The Phase I report deals with the morphology of impoundments
and further discusses the details of nutrient enrichment.
Coliforms will tend to settle in the impoundment, but
the supply from agricultural runoff and the treatment plants should
keep a constant if not increasing supply.
Temperature of the surface waters will increase due to
insolation.
Since primary productivity occurs in the upper surface
waters, dissolved oxygen may become supersaturated in the upper
layers while going to zero in the hypolimnion.
The effects below the impoundment will depend on the conditions
in the reservoir and the depth from which the water was released.
Presently, the water quality below the dam site is "C" quality. Basing
enhancement by low flow augmentation on the existing "B" quality water
above the dam may be a misconception because the impoundment in conjunc-
tion with the surrounding land characteristics will possibly alter this
present water quality.
Adverse effects downstream can be expected on dissolved oxygen
concentrations, sludge levels, color, turbidity, temperature, chemicals
and nutrients. The magnitude of these effects will be dependent upon
the amount of primary production occurring in the reservoir, the
41
-------
amount of downstream wastes discharged to the stream with the sub-
sequent oxygen demands exerted in the reservoir and downstream.
Coliforms concentrations would be reduced by protecting the present
primary treatment plant. However, the effects of this protection are
extremely small in terms of beneficial coliform, nutrient and dissolved
oxygen concentrations and general water quality improvement.
Another problem may occur when the reservoir receives its
initial filling. Flow must be regulated so that conditions downstream
do not become worse as a result of minimum flow release. Adequate flow
must be maintained so as not to degrade any further the "C" segment of the
river below Claremont. If the eutrophication rate is slow, color, turbidity,
and the chemical constituents downstream may benefit from the augmented
flow, but present usage and topography of the basin indicate that increased
eutrophication is likely. If increased eutrophication occurs then the
augmented flow water quality will be downgraded and the achievement of
desired benefits from this flow could be hindered.
With the recreational benefits initiated by the impoundment,
summer home development around the reservoir will occur. With the realization
that the reservoir may be subject to increased rates of eutrophication,
evaluations of the water quality impacts associated with the increased
development are especially important. This development, if not controlled
by zoning, results in erosion prone roads and poor, leaky septic systems.
These conditions could induce increases in sludge buildups, nutrients,
42
-------
coliforms, chemicals and a decrease in dissolved oxygen. Thus, summer
home development should be controlled according to sound zoning
ordinances which account for environmental constraints as well as
economic benefits so as not to enlarge any eutrophication problems.
Non-structural flood control methods in the Claremont area
will have the most positive impacts on water quality. The degree of
significance is determined by the extent of land use controls. If the
controls are merely floodproofing of existing buildings, then water
quality will remain relatively unchanged. However, when land use con-
trols include clearance of structures, developmental controls, and
restrictive uses of the flood plain, then impacts on water quality
will become more significant. If a buffer strip of land is reserved
for flood damage reduction, then it can be used for water quality enhance-
ment, provided it remains as open space and is not covered to a large
extent by asphalt or other impervious surfaces. This buffer strip can
absorb some of the runoff from the developed areas. Consequently, many
of the contaminants in storm water runoff can be reduced or removed and
as a result land use controls could have beneficial effects on the levels
of dissolved oxygen, sludge buildup, color and turbidity, coliforms, chemicals
(especially from the roads), nutrients and other contaminants contained
in the runoff.
During the initial clearing phases, turbidity may be adversely
affected by the increased silt and sedimentation usually associated with
construction and demolition sites. The effects of this are generally
short-term and can be mitigated by preventive measures.
-------
Summary:
The Claremont Proposal, because of its surroundings, may pose
more significant problems for water quality than were originally
anticipated. Nutrient enrichment from agriculutral runoff and waste dis-
charges pose a serious threat to the aesthetic and physical quality of
the reservoir.
Downstream effects will depend on the quality of the water
released from the reservoir. When the reservoir is being filled, care
should be taken to maintain an adequate flow so that further water
quality degradation can be prevented in the already "C" classified segment
of the river below Claremont.
Summer home development and recreation should be planned
judiciously accounting for the environmental constraints in the area
as well as the economic benefits.
The non-structural program for the Sugar River has the most
positive impacts. The majority of these impacts will be localized in
the Claremont area but the degree of water quality improvement from them
may be questionable.
44
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WHITE RIVER WATER QUALITY IMPACT EVALUATIONS
Background;
The White River has a drainage area of 712 square miles, and
rises on the slopes of Bartell Mountain in the Town of Ripton, Vermont.
It flows generally in a southeasterly direction to its confluence with
the Connecticut River at White River Junction. The Basin has a rugged
watershed with steep slopes and very little concentrated fall and
channel pondage.
The White River has a total length of 58 miles, with a total
fall of 2,170 feet, of which 1,600 feet occurs in its upper nine-mile
reach. The lower reach of the river has a relatively flat gradient
dropping 4.5 feet in 1.5 miles to the mouth of the river. The highest
elevation is 3,780 msl on Mt. Wilson in the Town of Ripton.
The three principal tributaries of the White River; the First,
Second and Third Branches, comprise about 44 percent of the total drainage
area. The First Branch, with a drainage area of 103 square miles, rises
in the Town of Washington. It is 21 miles long with a fall of 880 feet.
The Second Branch, with a drainage area of 73 square miles, rises in the
Town of Williamstown. It has a length of 25 miles with a fall of 430 feet.
The Third Branch rises in Roxbury and has a length of 26 miles, with a
drainage area of 136 square miles and a total fall of about 470 feet.
The White River joins with these three principal tributaries,
within a distance of about 7 miles. Peak flood flows from these three
tributaries and the White River itself meet almost simultaneously in this
45
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seven-mile reach, setting up a particularly bad situation on the
White River and making the White River a major contributor to flood
flows on the Connecticut River downstream.
Besides flooding due to snowmelt and severe rainfall, many
communities along the river face the additional threat of flooding caused
by ice jams. Hartford, Vermont is one of the larger communities along
the White River which has been bothered by such flooding in the past.
To combat this problem, a small local protection project was authorized
by the Chief of Engineers in September, 1968. It provided for channel
improvements in the two-mile reach of the White River immediately up-
stream of its confluence with the Connecticut River, in the eastern part
of the Town of Hartford. Construction was completed in 1970 at a cost
of $334,000.
The Gaysville Reservoir project is located in central Vermont
within the Towns of Stockbridge and Rochester in Windsor County and the
Town of Pittsfield in Rutland County. The dam site is located on the
White River, 0.5 mile southwest of Gaysville Village, and 31.6 miles above
the confluence of the White and Connecticut Rivers. The reservoir termin-
ates near Talcville Village, which is one-mile south of Rochester.
Table 9 indicates the various stages, pool depths and acre-feet
available in the reservoir.
46
-------
Table 9
Gaysville Dam and Reservoir
Item
Stream Bed
Winter Pool
1 May Pool
15 Nov Pool
1 Jan Pool
Spillway Crest
Kiev.
635+
725
745
745
725
800
Pool
Depth
0
90'
110'
110'
90'
165'
Acres
0
300
640
640
300
1,840
A.F.
0
9,000
18,200
18,200
9,000
81,800
From November 15 to January 1, an augmented flow addition of
98 cfs will be contributed downstream from storage releases in antici-
pation of winter-spring floods. After January 1 until April 1, the
winter pool will be maintained and outflow will equal inflow. Around
May 1, after the spring runoff period, the recreation pool will be
established and the pool level will be maintained until November 15.
The topography of the reservoir area is dominated by hillsides
and mountains rising sharply from the narrow river valley. The reservoir
borders on the Green Mountain National Forest to the West with numerous
peaks rising to elevations of over 3,000 feet and forming the divide
between the Connecticut River Basin and the Lake Champlain drainage basin.
The planned real estate acquisition would include purchase of
the dam site, work areas, and the reservoir area to the spillway crest
elevation, plus an additional minimum horizontal distance of 300 feet. Of
the 3,200 acres of land acquisition, 40% is wooded and used for tree
farming, 31% is devoted to tillage of crops such as corn, alfalfa and hay
and 13% is primarily used for dairy farming. Developed residential land
amounts to approximately 4% and less than 1% is utilized industrially and
47
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commercially. The area of the roads and waterways total about 250 acres.
About 7% of the remaining acreage is classified as potentially developable
land.
Approximately 70% of the improvements are residential, while
about 15% are farms. The remaining improvements consist of 1 industrial
and 10 commercial developments, 1 public building and 12 small miscellan-
eous buildings.
State Routes 100 and 107 are located within the reservoir area
and generally follow the valley floor. Fifteen miles of these roads, as
well as two miles of town roads, would require relocation. Relocation
of these roads is necessary if both local and through traffic are to be
served. Upon completion of Interstate Route 89 through Bethel, Vermont,
a substantial volume of traffic to and from the Rutland area would use
these relocated highways. Route 100 falls under the auspices of the
State-enacted "Scenic Corridors Act" of 1966. The beautification standards
set forth in this Act will be met and cost-sharing negotiations for
features that exceed existing Federal standards will be made with the
State during the design of the project.
The White River is classified "B" and is able to support a
cold water fishery above the Town of Bethel, which is below the reservoir
site.
Water Quality Impact;
Table 10 indicates the water quality evaluations made for the
Gaysville Reservoir and the completely non-structural proposal which
includes flood plain clearance.
48
-------
Table 10
Gaysville Proposals
Considerations
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Remarks and
Miscellaneous Information
Effects on waCer quality in
area of impoundment.
- -/O N/A 0 +
N/A
"utrient enrichment from agricultural run-
off may cause increases in algal popu-
lation and slight increases in nutrients.
DO and temp will be affected by stratifi-
cation.
Effects on water quality
below the impoundment.
-/O -/O -/O N/A 0 + -/O 0 N/A
Changes induced are slight. Conforms de-
crease due to reduction in number of
treatment plants rendered inoperative
by floods.
Effects on water quality due
to changes in land use in
the impoundment area.
N/A 0
H/A
Effects of non-structural
proposals for White River.
+ + +/- 0 0 + 0 + N/A +
Summer camp development may cause degrada-
tion by encouraging poor roads, over-
crowded or poorly constructed septic
systems, thus adding non-point source of
nutrient influx.
If clearing is incorporated into the non-
structural program, a buffer strip could
enhance water quality by removing some
contaminants from runoff. Some temporary
increase in turbidity is expected if
flood plain clearance is involved.
LEGEUD:
0
+/-
-/o
N/A
Effects could inhibit or adversely affect the ambient concentration levels slightly.
Effects could enhance slightly the ambient conditions in the water body.
Conditions remain unaffected.
Could have adverse and/or beneficial effects.
Adverse effects are felt to exist, but may be negligible or readily controlled.
Not applicable.
-------
Sinc/e the water quality above and within the reservoir area
is excellent and development in this area is limited, the reservoir
is not expected to produce serious effects on water quality. The general
physiological changes which will occur are associated with most deep
reservoirs and are due to the change in the energy regimes. Stratification
and material accumulation will occur which would lead to a change in dis-
solved oxygen, sludge accumulations, color and turbidity, coliforms,
temperature, chemicals and nutrients.
Dissolved oxygen will decrease with depth and there will be
some accumulation of sludges, chemicals and nutrients. Nutrient and
chemical accumulation should be monitored since basin activities such
as tree farming, dairying and crop productions and the lack of advanced
treatment: plants could cause measurable influxes of these substances. If
algal problems begin to appear, then increases in sludge deposits, turbidity
and nutrients from algal decomposition would occur. Coliforms will
decrease in numbers due to settling. Temperature profiles will occur as
in most deep reservoirs. Releases should be controlled so as not to inter-
fere with the present cold water fisheries in the river. Pool fluctuations
should be planned so as not to cause bank destabilization.
Downstream releases from the reservoir are expected to induce
only slight - if any - changes in water quality. If productivity is high
in the reservoir or the releases are not planned to account for temperature
and dissolved oxygen considerations, then there would be adverse effects
50
-------
on dissolved oxygen, turbidity, temperature, and nutrients. Sludge
deposits may not be removed in some portions of the river if the peaks
are removed from the high flood flows. However, the topography of the
river is such that it doesn't encourage sludge buildups. Treatment
plants will not be rendered inoperative by flooding and hence* coliform
concentrations show a positive impact of the reservoir. Nutrient and
dissolved oxygen concentrations are also lower than they would be if
the plant were rendered inoperative. However, the nutrient and dissolved
oxygen benefits derived are small compared to the overall effects
generated by the impoundment and by other factors.
Summer home development around the reservoir could induce the
most serious threat to water quality in the reservoir. Unless develop-
mental controls or restraints are encouraged by the State and/or Towns,
overcrowding of septic systems, or poorly constructed septic systems,
poor roads and exposed construction sites could result, leading to
aesthetic and water quality degradation.
The non-structural program for the White River Basin would
encourage positive impacts on water quality by limiting flood plain
development and by allowing a strip of land to act as a buffer zone to
provide some removal of contaminants from runoff. When flood plain
clearing occurs, there will be some temporary increase In turbidity,
however. The magnitude of these impacts is not known at this time.
51
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Summary;
Gaysville Reservoir Is expected to have only slight effects
on water quality. However, if nutrient influx from non-point sources
is higher than expected, eutrophication problems could occur. Downstream
effects from the reservoir are expected to be slight provided flow
releases are carefully planned. Summer home development around the
reservoir should be controlled to prevent water quality and aesthetic
degradation. The non-structural program could enhance water quality but
the magnitude of the impacts are unknown.
52
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AMMONOOSUC RIVER WATER QUALITY IMPACT EVALUATIONS
The Ammonoosuc River, which has its headwaters at the Lake of
the Clouds on Mt. Washington has a length of approximately 58 miles. It
falls 3,470 feet in its first 8.6 miles. In the section from Bretton
Woods to the mouth, a distance of 47 miles, it has an average slope of
25 feet per mile. The total drainage area is 402 square miles. It
flows westerly to Bethlehem Junction in Grafton County, northwesterly to
Littleton and then southwesterly through Lisbon and Bath to its junction
with the Connecticut River at Woodsville. The River upstream of Littleton
lies in a valley with steep sides with no sizeable areas for overbank
flow. Southwesterly of Exit 42 on the Interstate 1-93, the River has
developed a fairly wide floodplain along U.S. Route 302, an area that is
under pressure for future development.
Flooding along the Ammonoosuc River has occurred in every season
of the year with ice jams causing floods as significant as those caused
by snowmelt and/or torrential rains. The flood of record, by historical
accounts, was the November, 1927 Flood.
Two major alternatives for reducing flood damages in the
Ammonoosuc River Basin have been developed. These are: 1) non-structural
flood damage reduction measures only; 2) the construction of Bethlehem
Junction Dam and reservoir plus non-structural measures.
The Bethlehem Junction dam site would be located on the
Ammonoosuc River in the Town of Bethlehem, New Hampshire, about 0.9 miles
53
-------
above the community of Pierce Bridge. The reservoir would extend to
the Twin Mountain area in the Town of Carroll. The project would be
developed primarily as a multi-purpose reservoir for recreation and
vTlood control and incidental low flow augmentation for enhancement to
downstream fisheries.
Table 11 indicates that the impoundment depth could vary
from 31 feet to 69 feet with the average annual depth ranging from 42 feet
to 55 feet.
Table 11
Bethlehem Junction Dam and Reservoir
Item
Stream Bed
Winter Pool: Min.
Ave.
15 June Pool
15 Sept Pool
Spillway Crest
Elev.
1210+
1341
1352
1365
1365
1379
Pool
Depth
0
31'
42'
55'
55'
69'
Acres
0
570
800
1,090
1,090
1,440
A.F.
0
18,500
26,000
37,000
37,000
55,600
The reservoir from Twin Mountain down to the dam site is
located on broad, flat terraces. These terraces narrow down at the dam
site and from there, the river makes a steep descent until it passes
Littleton, N.H.
The project, as considered, would disrupt 18 residential, 20
commercial establishments, a Catholic Church, a State Police building and
a State Highway Maintenance Garage. These improvements all border the
54
-------
river in the Towns of Carroll and Bethlehem. Through appropriate
planning with State and local governments, new areas would be provided
for resettlement of those affected near the project. Land acquisition
totals 1,900 acres, of which 1,440 acres is located below spillway
crest elevation. The remaining 460 acres are situated within the
300-foot horizontal buffer zone. Exceptions to real estate acquisi-
tion in the 300-foot buffer zone may be made where possible.
Approximately half of the 1,900 acres of land required for
development would be located in the Town of Carroll. Eighty-nine percent
of this 1,900 acres is either forested or idle and reverting to forest.
There are no active farms in the reservoir area. Agriculture has been
rapidly declining in Bethlehem and is currently insignificant in Carroll.
Both towns have little industry at present.
There is access to the dam site which runs along the northerly
side of the Ammonoosuc River. This highway would be relocated for a
distance of about 6 miles, starting near the Fierce Bridge and running
along the northern periphery of the reservoir and joining new relocated
U.S. Route 3 and 302 at Twin Mountain. Sections of both highways are
presently being relocated and, exclusive of a few short stretches which
will require raising, will be above the Bethlehem Junction Reservoir.
Water Quality Impact;
Table 12 indicates the water quality evaluations for the
Bethlehem Junction Proposals. The Ammonoosuc River has a "B"
classification.
55
-------
Since the Ammonooauc River Basin is not presently under develop-
mental pressures, the effects of the Bethlehem Junction Reservoir are not
expected to induce significant changes in water quality. However, the
minimum depth of the impoundment indicates that thermal stratification
will occur. Additionally, due to the stratification and the impoundment's
physiography a decrease in dissolved oxygen at depth will occur along with
increases in sludge deposits, color, turbidity, chemicals and nutrients.
Some nutrient influx will occur from poor subsurface disposal sites up-
stream. Coliforras will have a tendency to settle, thus showing a reduction
in their concentrations. In any case, the changes induced in the impound-
ment, with the present development in the basin, will be slight.
Downstream below the impoundment, the adverse effects of the
structural proposal are again minimal. Sludge flushing may be reduced
since high flows and the associated scouring action will be reduced by
the flood control structure. However, the sludge buildup is expected
to be minimal.
Low flow augmentation is expected to enhance dissolved oxygen
concentrations and dilute chemical contaminants that are in the river
below the impoundment. However, this augmentation cannot be substituted
for waste treatment required by the 1972 Water Quality Amendments.
The reservoir will offer protection to treatment plants located
in the floodplain and thus reduce the influx of coliforms that occurs when
the treatment plants are rendered inoperative by floods. However, the
reservoir may contribute a higher nutrient concentration downstream than
is already present by releasing water of higher nutrient levels.
56
-------
Table 12
Bethlehem Junction Proposals
Considerations
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Remarks and
Miscellaneous Information
Effects on water quality in
area of impoundment.
N/A 0 +
N/A
Due to limited development in the basin,
effects will be very minimal. Some changes
associated with impoundments will occur.
Effects on water quality
below the impoundment.
+ -/O; 0 0 0 + 0 + N/A
Sludge is not expected to build up exert
much BOD or DO added by augmentation.
Littleton treatment plant spared by floods
chemicals diluted but more nutrients releas-
ed since they are collected in impoundment.
Effects on water quality
due to changes in land use
around the impoundment.
-/O -/O -/O N/A 0 -/O 0 -/O N/A -/O
Effects may be minimal but development
around impoundment shouli be controlled
so as not to cause severe effects.
LEGEND:
0
-/O
N/A
Effects could inhibit or adversely affect the ambient concentration levels slightly.
Effects could enhance slightly the ambient conditions in the water body.
Conditions remain unaffected.
Adverse effects are felt to exist, but may be negligible or readily controlled.
Not applicable.
-------
Land use around the impoundment could have the most damaging
effects on water quality in the reservoir. If land use control is not
incorporated in the recreational developments around the impoundments,
overcrowding of summer homes, poor septic systems, erosion prone roads
and aesthetic deterioration can result. Uncontrolled development would
cause increases in sedimentation, sludge deposits, color, turbidity,
coliforms, chemicals and nutrients.
Summary:
Development in the Ammonoosuc River Basin is limited and
hence, the effects of the reservoir within the basin will be minimal.
The effects of development around the reservoir if not controlled could
induce the most serious effects on water quality in the impoundment.
58
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NON-STRUCTURAL PROPOSAL FOR THE NORTHERN PORTION
OF THE CONNECTICUT RIVER BASIN
Water Quality Impact;
The northern portion of the basin extends from the confluence
of the Deerfield River to the headwaters in Canada. The water quality
impacts for the non-structural proposals in the northern portion of the
basin are indicated in Table 13.
Due to the limited development in the northern portions of
the Connecticut River Basin, the non-structural flood damage reduction
proposal planned for this area will have minimal effects on water quality.
Any clearing and functional open space preserved in the floodplain can
act as a buffer zone between the urban and agricultural areas and the
river. This buffer zone will remove some of the contaminants contained
in runoff before it reaches the river. These effects will remain minimal
as long as development is limited.
Presently the main influence on water quality in the northern
basin is exerted by the power and paper companies. The few urban towns
in the upper basin are scheduled for pollution abatement measures in order
to comply with the Water Quality Amendments. With more stringent controls
over paper plant waste treatment and stream flow regulation, the upper
basin should be able to claim excellent water quality.
Summary;
The effects of the non-structural flood management program
for the northern basin will be similar to those expected in the southern
59
-------
basin only much less significant, as long as development remains low.
Presently, in the northern portion of the basin, water quality is
influenced primarily by the paper and power companies.
60
-------
Table 13
Non-structural Proposal for Upper Connecticut
Considerations
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Remarks and
Miscellaneous Information
Effects on non-structural
proposal for the
Upper Connecticut River.
+/0 +/0 +/-
0 +/0 0 +/0 N/A +/0
If clearing is incorporated, buffer strip
will enhance water quality be removing
some contaminants from runoff. However,
effects minimal since development in
Northern ConnecticutRiver Basin is limited.
LEGEND:
0 Conditions remain unaffected.
+/0 Benefits are felt to exist, but minor and easily negated or influenced by other factors.
+/- Could have adverse and/or beneficial effects.
N/A Mot applicable.
-------
PASSUMPSIC RIVER WATER QUALITY IMPACT EVALUATIONS
Background:
The Passumpsic River is formed by the confluence of its east
and west branches in the Town of Lyndon, Vermont and flows in a south-
westerly direction to Lyndonville. The drainage pattern of the watershed
is generally fan-shaped. From this point, if follows a southerly course
through St. Johnsbury and Passumpsic to its confluence with the
Connecticut River at East Barnet. The mainstem has a total length of
approximately 23 miles, a total fall of about 230 feet, and a drainage
area of 507 square miles, all in Vermont.
The Moose River, the Passumpsic's main tributary, rises in the
Town of East Haven and flows in a southerly direction to Concord and then
westerly to its confluence with the Passumpsic River at St. Johnsbury,
Vermont, a total distance of about 25 miles. It drains an area of
127 square miles and has a total fall of about 1,230 feet of which 770 feet
are in its upper 14 miles.
The West Branch of the Passumpsic drains an additional 66 square
miles and adds an additional 16 miles in length, while the East Branch
drains an additional 80 square miles and adds an additional 18 'miles in
length. The West Branch falls about 1,500 feet and the East Branch
falls about 1,400 feet.
62
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The upland topography in the watershed is steep. Tributary
channel slopes vary from very steep to relatively flat. For example,
the upper reaches of Miller Run, a tributary to the Paasumpsic, fall
at 100 feet per mile and then level off to 6 feet per mile in the lower
reaches.
Present land use in the watershed is estimated as follows:
74 percent forest, 20 percent distributed between cropland and pasture,
and 6 percent urban and miscellaneous. It is expected that forest use
will remain constant in the immediate future while agriculture will
decrease and urban use increase
There are many acres of ponds and lakes in the area considered
for flood control measures. These ponds provide a limited amount of
flood storage and have a negligible effect on flood flows. There are
about 2,000 acres of wetlands in the watershed, but:, with the exception
of Victory Bog with over 1,000 acres, these are small areas located in
the headwaters and have a limited effect on flood flows. Victory Bog
provides a significant amount of natural flood storage, but it is not
sufficient to prevent floodwater damages from occurring on the lower
reaches of the Moose River.
In order to reduce flood damages in the Passumpsic River System,
several flood management alternatives have been proposed. The Corps of
Engineers developed plans for a large reservoir in the Victory Bog area
and the Soil Conservation Service developed plans for several small water-
shed projects.
63
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Victory Proposal;
The Corps of Engineers' Victory Dam site would be situated
on the Moose River about 17.2 miles above its confluence with the
Passumpsic River and 15 miles northeast of St. Johnsbury, Vermont in
the Town of Victory, Essex County, Vermont. The project was designed
for flood control storage, recreation, downstream hydroelectric energy,
and fish and wildlife enhancement, the latter two resulting from low
flow augmentation.
The Town of Victory, the primary area to be protected by the
reservoir, is 40 square miles in area. It is basically composed of wood-
land, with scattered farms and residences. The surrounding area is
mountainous and heavily forested -with Burke and Umpire Mountains to the
west, East Haven Mountain to the north, Stone Mountain to the east and
Miles Mountain to the south.
Victory, with a population of about 50, has no schools, churches,
stores, zoning ordinances or paved roads. Children are bused from the
Village of Gallup Mills in the Town of Victory to schools in the adjoining
Town of Concord, Vermont.
The topography of the reservoir area is dominated by a large
flat wet bog of over 1,000 acres principally formed by a glacial outwash
and generally surrounded by hilly to mountainous terrain with impervious
glacial till predominating the overburden on the reservoir periphery.
Anticipated land acquisition amounts to 5,800 acres of woodland
of which 85% is equally divided between softwoods and hardwoods. Wet
and brush land totalling 1,100 acres make up the remaining acreage. This
land would be purchased to spillway crest elevation 1,196 or 300 feet
64
-------
horizontally from elevation 1,183, the full pool, whichever is
greater. This total acreage includes 450 acres on the north side
of the reservoir, and another 450 acres on the west side which will
be acquired specifically for immediate and future recreational
development, while 1,000 acres on the east side will be acquired for
wildlife mitigation measures.
Construction of the project would require the relocation of
four miles of gravel road to provide access to local residences which
would not be purchased. A relocated highway, five miles in length, will
follow a route along the western side of the reservoir to connect the
villages of Victory with Gallup Mils. This road will also serve as
an access to the proposed and future recreation developments at the
project site.
The reservoir operating procedure would establish the pool
at the start of the summer season and would permit minimum flow releases
of 50 cfs for the months of June and July and 75 cfs for August. These
flows can be maintained 95% of the time with less than a foot of draw-
down. The maximum summer drawdown anticipated for critical dry years
would be about four feet.
In September, following the recreation season, reservoir
releases would be increased to 135 cfs to augment natural flows through
the normally flow deficient fall months. By January, these flows would
65
-------
then be decreased to 100 cfs until May when a minimum flow release of
50 cfs would be required to re-establish the recreation pool by 1 June.
Depending on the threat of spring flooding and anticipated spring runoff,
adjustment in reservoir filling would be required.
Significant changes in the flow regime will be induced as is
indicated by comparing the above flow release information with the present
flow conditions (Table 14) at the proposed site.
Table 14
USGS Flow Data on the Moose River Taken at Victory, Vermont in 1968
Maximum discharge for 1968 1600 cfs 21.3 csm March 24
Minimum discharge for 1968 6.6 " .09 " August 17
Maximum discharge between 1947-1968 2940 " 39.1 " April 21, 1950
Minimum discharge between 1947-1968 3.7 " .05 " Sept 16/17,'48
Average discharge for 21-year period 135 " 1.8 "
The following Table 15 lists the pertinent information concerning
the various operating elevations of the Victory Dam.
Table 15
Victory Dam and Reservoir
Item
Stream Bed
Winter Pool, Min.
1 June Pool
1 Sept Pool
Emergency
Spillway Crest
Elev.
1125
1156
1175
1175
1196
Pool
Depth
0'
31'
50'
50'
71'
Acres
0
2030
2880
2880
3800
A.F.
0
35,000
82,000
82,000
151,000
66
-------
Water Quality Impact:
Table 16 indicates the evaluations made for the Corps of
Engineers' Victory Proposal.
The evaluations concerning the effects on water quality due
to land use reflect no change since there are no significant discharges
to the Moose River above the impoundment site, there are no significant
urban areas within this upper portion of the basin, and there are no
significant development plans scheduled for this area. The area is
presently designated as open space.
The Moose River is presently designated as a "B" classification
and is capable of supporting a cold water fishery. The bog environment of
the proposed site is unusual and consequently exerts certain influences on
water quality. The water is very acidic and dark in color due to the
leaching of tannic acid from the surroundings. During the dry periods,
the bog acts as a sponge and consequently the flows are minimal.
Placement of an impoundment within these surroundings poses
special considerations concerning flow releases and maintenance of
water quality within the impoundment. With the establishment of a pool
30 feet deep over the organic rich bog, a very high biochemical oxygen
demand will be exerted and thermal stratification will probably occur.
With the acidic condition of the water and rich organic content, decompo-
sition might be anaerobic. Hence, dissolved oxygen within the impoundment
could be induced to levels below 6 mg/1 and subsequently violate Vermont
standards for the river's classification. Organic sludge deposits would
67
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build up behind the impoundment due to the large volume of organic
material in this portion of the basin.*
Released water that would be used for augmentation may
exert an oxygen demand on the downstream water, rather than enhancing
it, if the released water has a high oxygen demand «and a low dissolved
oxygen content. However, the augmented flow below the impoundment would
encourage the removal of sludge deposits immediately below the impoundment.
But sludge removal further downstream might be hindered since it may take
more than the augmented flow to move them. These downstream deposits
may depend on the high flood flows for their removal and these flows
would be eliminated with the Victory Reservoir.
Color and turbidity problems are common occurrences in bog
environments. The increased flow releases downstream may tend to spread
these problems below the impoundment site. If anaerobic conditions
establish in the impoundment, taste and odor effects downstream and
in the impoundment may be more severe.
*NOTE: When a reservoir area is flooded, the vegetation dies and the
organic matter released to the water from this source, as well as from
the topsoil, undergoes decomposition. Algae and other microorganisms
flourish. Odors, taste and color are imparted to the water and 10 to 15
years must elapse before decomposition of the putrescible substances within
the reservoir area has been substantially completed and the reservoir has
been stabilized. A state of equilibrium is reached when the water within
the reservoir takes its quality from the incoming water. The rate of
improvement, or stabilization, when referred to conditions of equilibrium,
is approximately 14% annually which implies 90% improvement in about
14 years for those reservoirs which inundate uncleaned, flooding swamps
that have higher amounts of color and microscopic organisms.(D
(1) Fair, G.M. and Geyer, J.C., Water Supply and Waste-Water Disposal.
John Wiley & Sons, Inc., New York, Chapman and Hall, Limited, London.
68
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Table 16
Victory Proposal
Considerations
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Remarks and
Miscellaneous Information
Effects on water quality in
area of impoundment.
0 00 +
0 N/A
No effluent discharges to add nutrients but
high pH and decaying organic material that
was inundated contribute soluable nutrients
and organic sludge deposits. This organic
material exerts a very high BOD. Produc-
tivity down in acid wastes.
Effects on water quality
below the impoundment.
0 0
N/A
Contaminants are not from discharges, but
are induced by changing to an impoundment
regime. Flow will be augmented but may be
low in DO due to low productivity and high
BOD in the released water.
Effects on water quality
due to changes in land use.
00 0 00000 N/A 0
No development now or planned.
LEGEND:
- Effects could inhibit or adversely affect the ambient concentration levels slightly.
Effects induced could inhibit or adversely affect ambient concentration levels to such
a degree as to violate the standards set by the waterbodies classification.
+ Effects could enhance slightly the ambient conditions in the water body.
0 Conditions remain unaffected.
+/- Could have adverse and/or beneficial effects.
N/A Not applicable.
-------
Since there are no discharges in the area of the impoundment,
coliform numbers are expected to decrease in the impoundment due to
nettling. Treatment plants below the impoundment will be protected, and
hence, the coliform number is expected to be lower. Temperature effects
within the impoundment will vary. Thermal stratification will occur
allowing colder water to remain at depth and warmer water to remain
near the surface. The deeper water will be colder than that which
occurs under present conditions. However, due to decomposition and its
associated oxygen demand, the thermal stratification may induce an oxygen
deficit in these lower waters. Release of these waters downstream could
enhance fisheries by a cold water release, but it could also limit
fisheries by inducing an oxygen deficit downstream. Warm surface water
releases could influence cold water conditions downstream, also. Thus,
caution must be exercised when downstream releases are considered.
Summary:
The impoundment may violate the dissolved oxygen requirements
for the stream's classification due to the decomposition of the organic
material that is inundated. With the highly acidic nature and dark color
of the water, recreational benefits may be hindered. The impoundment will
encourage thermal stratification and anaerobic decomposition in the
hypolimnion. The impoundment through inundation of the bog may, with time,
reduce the volume of leached acidic material. However, the reduction will
take many years.
70
-------
Releases downstream during the summer months will consist
of larger volumes of acidic water. The water released could contain
taste and odor problems, raise downstream temperatures and induce
downstream oxygen demands.
Primary production will be limited in the impoundment due to
the acidic nature of the water. The nutrients released from decomposition
will remain in solution under the acidic conditions until the released
water is buffered by downstream receiving waters and the pH is lowered.
The nutrients will then be available for primary production.
71
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SMALL WATERSHED PROJECTS
Passumpsic River Proposal:
Another flood management solution for the Passumpsic River
Basin is sponsored by the Soil Conservation Service under their
P.L. 566, Small Watershed Program. For the Passumpsic, a series of
small flood control dams were proposed. Three SCS programs for flood
management were selected for study following a public meeting held on May 23,
1974 and the Study Management Team evaluator's meeting held on May 29, 1974.
The programs are:
1) A non-structural program, which proposed reducing flood
damages by floodproofing or removal of damageable structures in the flood
plain, flood warning and evacuation, flood insurance and flood plain
zoning.
2) A combination structural and non-structural program con-
sisting of five dams located on Bean Brook, East Branch of the Passumpsic
River at East Haven, Mill Brook, Calendar Brook and Hawkins Brook.
3) A combination of structural and non-structural measures
consisting of five dams.located on Bean Brook, Mill Brook, East Branch
of the Passumpsic River at East Burke, Calendar Brook and Hawkins Brook.
The small watershed project sites were evaluated only in terms
of sediment pool depths as this is the only depth considered by the SCS
in the supplemental study. However, in all the small watershed projects,
a range of beneficial pools is possible. With these deeper pools, water
, 72
-------
quality will be subject to physical, chemical changes just as in the
larger impoundments proposed by the Corps of Engineers. The extent
of these changes will be dependent on surrounding development,
geology, topography, climate, pedology, depth, shape and lake orientation
to name just a few.
The area to be considered for small watershed projects is
located above St. Johnsbury and totals 374 square miles or 239,360 acres.
The following are the dimensions for the sediment pools at the watershed
sites proposed for the Passumpsic River drainage area by the Soil Con-
servation Service.
SEDIMENT POOL
Site Number & Location
4 Bean Brook
5 East Branch Passumpsic River
(East Haven)
6 Mill Brook
8 East Branch Passumpsic River
(East Burke)
9 Calendar Brook
16 Hawkins Brook
Acres
20
30
5
50
5
20
Acre-feet
150
140
30
340
70
60
Ave. Depth
7.5'
4.7'
6'
6.81
14'
3'
8 East Burke - alone 70 520 7.4'
Water Quality Impact:
Table 17 gives the evaluations pertaining to the effects these
projects will have on water quality. Presently, the waters of the
Passumpsic system are classified to meet "B" standards, and the small
sediment pools are expected to have little effect on the present water
quality.
73
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In the shallower Impoundments as nutrients collect, photo-
synthetic activity may cause an increase in oxygen levels. However, during
the summer months the pools will also warm resulting in lower dissolved
oxygen saturation levels. Sludges, sediments, coliforms and nutrients
will accumulate to a minor degree in the shallower pools. However,
coliforms will settle and show a decrease in concentrations.
In the de€'.per pool at Calendar Brook, stratification may occur
and a dissolved oxygen profile during the summer months may occur. The
importance and extent of the profile will depend on the depth of light
penetration and the amount of productivity occurring.
Downstream releases may influence the temperature and dissolved
oxygen levels slightly in the receiving water until the water cools and
is reaerated. Sludge removal may be reduced since the flushing action of
flood waters will be prevented. Downstream treatment plants will be
protected from damaging flood waters.
In the deeper Calendar Brook pool releases will have to be
controlled so that warm surface waters or deep, possibly oxygen deficient
cold water will not impair water quality downstream. When beneficial pools
are determined for the other projects, this same control will have to be
followed.
The non-structural program for the Passumpsic will induce some
temporary increases in turbidity when clearing occurs. However, the over-
all effects of flood plain zoning will allow the area of limited
development along the river to act as a buffer strip in removing some
74
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Table 17
Passumpsic River
Small Watershed Projects
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Considerations 3(5 £ ^ c 2. § = °
Effects of small watershed projects +/- -/O -/O 00+
on water quality in area of im-
poundment except:
Calendar Brook - - -/Q 0 0 +
Water quality effects down- -/O - 0 00+
stream below impoundments
except :
Calendar Brook -/O - 0 00+
Effects ot non-structural + 0 +/- 00 +
alternatives on water
quality.
LEGEND:
0)
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1 1 i £ ^ ' Remarks and
E- u as n z Miscellaneous Information
0 N/A - Photosynthesis may effect DO. Temperature
causes DO saturation level to decline.
Pool fluctuation increases sedimentation &
erosion. Coliforms settle out, nutrients
0 N/A - Stratification may occur as well as effects
above.
0 N/A 0 DO affected until released water reaerates
or cools; sludges may accumulate downstream.
Treatment plants protected; se->cic systen
backup controlled; therefore, decrease in
coliforms. Nutrient reduction by plant
protection offset by nutrients released
0 N/A 0 Calendar Brook releases will need to be con-
trolled, in addition to above.
u -i- N/A + Clearing increases sedimentation temporarily
If buffer strip of land is used, some con-
taminants in runoff such as nutrients,
chemicals, coliforms, mav be removed.
- Effects could inhibit or adversely affect the ambient concentration levels slightly.
+ Effects could enhance slightly the ambient conditions in the water body.
0 Conditions remain unaffected.
+/- Could have adverse and/or beneficial effects.
-/O Adverse effects are felt to exist, but may be negligible or readily controlled.
N/A Not applicable.
-------
contaminants contained in runoff. This should reduce some of the
oxygen demand existing in the stormwater runoff.
Summary;
The impacts of the small watershed projects on the water
quality in the Passumpsic system should be minimal if only the designed
sediment pools are considered. However, the deeper beneficial pools,
when determined will have the same associated characteristics as do
the large deep reservoirs. The water will be subject to thermal
stratification, dissolved oxygen profiles, and extended detention time.
The deeper impoundment releases could induce significant influence on
downstream water quality, and hence, should be controlled.
76
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Mill River Proposal
Background;
The Mill River watershed Is located In Hampshire and Franklin
Counties in Massachusetts. The stream originates in the eastern part
of the Berkshire Hills in the Towns of Goshen and Conway. It flows
through the Town of Williamsburg and the City of Northampton to its
confluence with the Connecticut River at the Oxbow. The Mill River was
diverted from its original course at a point near Smith College in
Northampton down to the Oxbow as a part of a local flood protection
project completed in 1941 by the Corps of Engineers.
The watershed encompasses about 59 square miles (37,760 acres).
Land use in the watershed is estimated as follows: 74 percent forest,
9 percent cropland, 5 percent pasture, 7 percent urban, and 5 percent
miscellaneous. In the next ten years, forest land use is expected to
remain constant, agricultural use to decline, and urban use to increase.
The upstream portions of the watershed are steep. In about
six miles from Highland Lakes to Williamsburg, the West Branch falls
900 feet. At Williamsburg, it is joined by the East Branch which has
similar slopes and by Meekin Brook with slopes over 200 feet per mile.
The Mill River below Williamsburg is less steep with a fall of 400 feet
in 12 miles.
There are 1,700 acres of flood plain along the Mill River in
Northampton and Williamsburg. Of this, about 1,000 acres is part of a
77
-------
common flood plain shared with the Connecticut and Manhan Rivers. This
common flood plain is divided about equally between agricultural and
wetland use and is not included in the study analysis. Land use in
the Mill River flood plain is estimated in Table 18:
Table 18
Mill River Watershed
Flood Plain Land Usei
I/
Land Use
Agriculture
Urban
Wetland & Woodland
Recreation Areas
Acres
170
140
310
80
Percentage
24
20
44
12
TOTALS 700 100
I/ Excluding flood plain common with Connecticut River.
There are about 250 acres of waterbodies consisting of lakes,
ponds, and reservoirs in the watershed. The Highland Lakes, Mountain
Street Reservoir, and Roberts Meadow Reservoir are the major bodies of
water. Scattered through the watershed are small wetland areas. One major
area, the Nungee Swamp, is located in the Beaver Brook drainage area. In
total, there is an estimated 700 acres of wetland in the watershed.
The Mill River, classified under "B" standards down to Northampton
and "C" standards from Northampton to the mouth at the Oxbow and the
Connecticut River, is subject to frequent flooding. Consequently, the
Soil Conservation Service has proposed several small watershed projects for
78
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flood control. The plans reviewed for the supplemental study consist
of one non-structural program and a structural program consisting of
three dams and certain associated non-structural measures of flood
control.
Water Quality Impact;
The three proposed reservoir sites are located on the East
Branch, West Branch and Roberts Meadow Brook. Impact evaluations for
the small watershed projects and the non-structural alternative are
listed in Table 19.
The impact evaluations pertain only to the sediment pools
for the three projects. Their depths are indicated below:
SEDIMENT POOLS
Location
East Branch
West Branch (Goshen)
Roberts Meadow Brook
Acres
10
20
60
Acre-feet
60
70
90
Pool Depth
6'
3.5'
1.5'
Generally, the small sediment pools are expected to have
minimal effects on the water quality of the Mill River. Dissolved oxygen
saturation levels will be lower in the pools due to the elevated tempera-
tures caused by insolation. If there are enough nutrients collected in
the pool, algal production may mitigate this oxygen deficit through photo-
synthesis. In addition to nutrients, some sludge deposits and coliforms
may accumulate in the pool. The coliforms settle and generally show a
79
-------
concentration decrease in the pool, while the sludge deposits will
exert an oxygen demand in the pool. Sedimentation and erosion may
occur as a result of pool fluctuation during high flow periods.
Downstream effects may be more significant since the
stream is presently under "C" standards. If reaeration or cooling
does not occur, the warmer released water with lower dissolved oxygen
concentration may impair the oxidation of waste loads from the
Northampton wastewater treatment plant and the Howmet Company. Flood
flow reduction may reduce the flushing of sludges; but downstream
treatment plants will not be subject to periods of inoperation as a
result of flooding. This will result in less coliforms and nutrients
being released downstream.
The non-structural program planned for the Mill River Basin
is limited to floodproofing of homes and businesses subject to damage
from the 100-year flood event, an effective flood warning system pro-
tecting open land, and maintaining open space in the flood plain. There
is no floodplain clearance proposed in this project, but future flood
plain encroachment will be curtailed. Consequently, the impacts of this
non-structural program on water quality will be minimal. The development
situation will essentially remain the same thereby inducing no changes
in the present water quality situation.
However, the projects also have recreation pools associated
with them. The depth of these pools is not established, but the SCS has
offered for each project a range of alternative depths. Some of the
beneficial pool depths could be in excess of 25 feet. These deeper
80
-------
Table 19
Mill River Proposal
Considerations
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Remarks and
Miscellaneous Information
Effects on water quality at
impoundments; East Branch,
West 'Branch, Roberts Brook.
+/- -/O -/O
0 N/A
Pools too shallow to stratify, therefore,
algae may increase supply of oxygen
through photosynthesis. But, increase in
algal population will result in increase
in BOD and nutrient influx when decompo-
sition occurs. Temperature increase re-
sults in decrease in oxygen saturation levet
Coliforms will settle out. Bank erosion
may occur as a result of pool fluctuation.
Effects on water quality down-
stream from East Branch,
West Branch, Roberts Brook.
0 N/A 0 Possibly low DO in water released downstream
as a result of warmer water. Sludge re-
moval restricted by elimination of flushing.
Treatment plants protected. Therefore, less
coliforms & nutrients released in downstream
reaches. Nutrients released from the im-
poundment mitigate the effects of reduced
nutrient levels from protected treatment
plants.
Effects on water quality due
to changes in land use
(Non-structural)
0000 N/A 0 Mo real chan".e in present water quality
situation.
LEGEND:
N/A
-/O
Effects could inhibit or adversely affect the ambient concentration levels slightly.
Effects induced could enhance slightly the ambient conditions in the water body.
Conditions remain unaffected.
Could have adverse and/or beneficial effects.
Not applicable.
Adverse effects are felt to exist, but may be negligible or readily controlled.
-------
impoundments will be subject to the morphological changes which will
include thermal stratification and dissolved oxygen profiles. The
amount of contaminant and nutrient influx will be more significant
because of the extended detention time these substances will have in
the deeper larger impoundments.
Summary:
The small watershed projects for the Mill River are not
expected to significantly effect the water quality at their sediment
pool levels. However, if insolation induces lower dissolved oxygen
levels in the released water, and reaeration does not occur, assimila-
tion of downstream waste loads may not readily occur. The
larger beneficial pools when proposed will induce more significant
effects on water quality and should be investigated thoroughly before
being accepted.
The non-structural program will not induce any significant
changes in water quality.
82
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Whetstone Brook Proposal;
Background:
Whetstone Brook is a small tributary entering the
Connecticut River at the Town of Brattleboro, Vermont. It originates
above Hidden Lake in Marlboro, Vermont, and flows 11 miles to its
confluence with the Connecticut. The watershed covers 28 square miles
or 17,900 acres. Whetstone Brook has three main tributaries entering
it; Halladay Brook, Ames Hill Brook, and the stream coming from the
Pleasant Valley Reservoir. There are two small dams in Brattleboro.
Present land use in the watershed is estimated as follows:
6% cropland, 4% pasture, 78% forest, 5% urban and 7'1 miscellaneous
(i.e., roads). The proportion of forest land is expected to remain
relatively constant over the next 10 to 15 years, while agricultural
land will continue to decrease and urban land increase.
The stream gradient is steep, and in ten miles the Whetstone
falls over 1,400 feet. The Whetstone is a very flashy stream, capable
of reaching peak flows in a few hours. There is very little natural
storage within the watershed to retard the flow of the water in the
brook. The Whetstone supplies no significant floodwater contribution
to the Connecticut River. However, its mountain stream flashflood
character does pose localized flood problems for the Town of Brattleboro.
The entire Whetstone Brook is presently classified "B" standard
except in the Pleasant Valley Reservoir which is classified "A". The
83
-------
overall water quality is generally excellent and the dissolved oxygen
content is very high.
Table 20 indicates the water quality impact evaluations per-
formed on the Whetstone Brook small watershed projects. The impacts
are addressed to the areas considered as the sediment pools. Some of
the projects will have associated recreational pools. The depth of
these recreational pools is not known at this time, but the SCS has
proposed a range of beneficial pool sizes for many of the impoundments.
The effects of these pools should be determined when the beneficial pool
size is decided.
Presently, the sediment pool sizes for the Whetstone Brook
projects are as follows:
SEDIMENT POOLS
Site Number and Location Acres Acre-feet
1.
4.
5.
6.
7.
9.
10.
Whetstone Brook below Hidden Lake
Ames Hill Brook
Halladay Brook
Tributary to Whetstone Brook
Whetstone Brook above Halladay Brook
Bonnyvale
Pleasant Valley
5
5
5
5
10
3
4
20
40
30
10
40
8
11
Pool Depth
4'
8'
6'
2'
4'
2.7'
2.8'
In addition to structural dams, one alternative includes 8,300
feet of diking near the mobile home parks, Melrose Terrace, and downtown
Brattleboro. The effects of the diking are also considered in Table 20.
84
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Table 20
Whetstone Brook Proposals
Considerations
Effects of small watershed
TJ
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N/A
Remarks and
Miscellaneous Information
DO through photosynthesis increased, but
temp
projects on water quality
in area of impoundments.
due to insolation will lead to decreased DO
saturation level. Sludge & sediment may
buildup slightly. Erosion may occur with
pool fluctuation and coliforras settle out.
Some nutrient accumulation occurs where
upstream septic seepage may enter. Sludges
exert a BOD.
Downstream effects on water
quality due to impoundments.
-/O 0 0 0 0 +
0 N/A 0 DO affected until released water is aerated
& cools, coliforms & nutrients are lower
due to less septic tank backup & treatment
plants protected. Nutrient effects mitigated
by nutrients released from impoundment.
Effects of diking on water
quality.
0 0
0 0 0 0 0 N/A 0
Diking displaces water to other areas, this
will result in more erosion and sedimentation
in areas not previously flooded or protected.
I.ffocts on non-structural alter-
natives on water quality.
+ 0 +/- 0 0 + 0 + N/A +
Any clearing will increase sedimentation tem-
porarily. If buffer strip of land is used,
i.1 mav remove some contaminants that occur
in storm water runoff such as nutrients,
chemicals and coliforms, thus reducing the
stormwater effects.
LEGEND:
0
+/-
-/O
N/A
Effects could inhibit or adversely affect the ambient concentration levels slightly.
Effects could enhance slightly the ambient conditions in the water body.
Conditions remain unaffected.
Could have adverse and/or beneficial effects.
Adverse effects are felt to exist, but may be negligible or readily controlled.
Not applicable.
-------
Water Quality Impact:
For the most part, the small sediment pools are expected to
have minimal effects on the water quality within the Whetstone. Dis-
solved oxygen in the sediment pools may be reduced slightly during the
summer months since the pools will warm and the water will have a
reduced saturation level. The oxygen supply will rebuild when the
released water reaerates and cools while moving downstream. Photo-
synthetic activity may reduce the oxygen deficit dictated by the water
temperature, if productivity is high enough. But sludge accumulations often
exert oxygen demands which may negate the effects of photosynthetic activity.
Some erosion may occur causing minor increases in turbidity as a result of pool
fluctuations, but the effects are expected to be small. Nutrients
may accumulate in the pools if upstream septic seepage or agricultural
runoff enters the pools. The accumulated nutrients are not expected
to pose any significant algal problems. Coliforms will tend to settle
out in the pool.
Temperature will be the most significantly affected water quality
parameter attributed to the small watershed projects. However, the
effects will be limited to the pool area and .immediately downstream.
The extent of the downstream effects will be dependent upon the amount
of cooling and reaeration which occurs. However, the abundance of oxygen
in the stream and the amount of reaeration available indicate that down-
stream effects will be minimal.
86
-------
The impoundments will serve to reduce downstream colifonn,
nutrient and oxygen demand increases by offering flood protection to
existing and future treatment plants. Oxygen demand and nutrient
loads released by the impoundments exert a more significant influence
over water quality then the reduction of these parameters afforded
through treatment plant protection.
The diking system planned for the Whetstone will displace
the floodwater to another unprotected area, leading to increased
erosion and flooding in the unprotected area. Used in conjunction with
other watershed projects, however, these effects will be significantly
reduced.
Non-structural approaches to flood management on the Whetstone
will cause temporary increases in turbidity if clearing is incorporated.
The non-structural approach can enhance water quality on the whole if a
buffer strip is used to partially remove contaminants contained in the
urban and agricultural runoff. This could reduce the nutrients, chemicals,
coliforms, and sediments which enter the stream via the runoff and exert
oxygen demands on the stream.
Summary;
The settling pools for the small watershed projects will not have
any major effects on water quality in the Whetstone Brook Basin. However,
the larger beneficial pools would and should receive full consideration
when their depths are determined. These deeper beneficial pools will be
87
-------
subject to thermal stratification and form dissolved oxygen profiles.
The amount of contaminant and nutrient influx will be more significant
because the detention time of these elements will be greatly extended
in the larger beneficial pools.
88
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TREATMENT COSTS FOR IMPAIRED WATER QUALITY
AT IMPOUNDMENTS
When an Impoundment undergoes the pressures of eutrophlcation,
thermal stratification is associated with a dissolved oxygen profile.
The profile shows high oxygen concentrations near the surface which
indicates high photosynthetic activity by algae. However the dissolved
oxygen profile generally goes very low even to zero in the hypolimnion
portions of the impoundment. Conditions in the hypolimnion become
anaerobic and hydrogen sulfide is a by-product of decomposition.
As a consequence of extreme eutrophication, obnoxious algal
blooms occur, fish are killed, taste and odor problems are encountered
and turbidity increases. These end products cause physical and aesthetic
degradation of the water body.
Once a waterbody experiences eutrophic conditions, treatment
cost for water use greatly increases. More chlorine is needed to oxidize
organic materials, the hydrogen sulfide causes equipment damage and
special treatment is often required to correct the taste and odor
problems.
In order to abate the extra treatment needed at the plants,
eutrophication control at the impoundment is felt to be the most
economical approach. Treatment generally consists of the installment
of aerating systems and the spreading of copper sulfate. Copper
sulfate suppresses algal growth, but does little to eliminate the re-
currence of algal blooms. Aeration breaks down the dissolved oxygen
profile and enhances circulation.
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Mechanical aerators generally consist of compressors which
generate the air supply, oxygen carrying tubes to carry the supply to
depths and air diffuser nozzles which disperse the oxygen in the
hypolimnion. Other monitoring equipment, shelters, etc. are also
needed for efficient operation and maintenance. The costs for installing
aerators varies with the size and type of equipment needed. Aerating
systems can range in orders of magnitude, with reaeration of flowing
rivers costing considerably more than reaeration of reservoirs.
For example:
"On the Passaic River, the achieving of a reasonably
reliable D.O. level of 4 mg/1 under present conditions by
instream aeration alone would require 15-75 h.p. units,
with total annual costs of $194,000, as compared to a
preliminary estimate of $785,000 for accomplishing the
same results by advanced waste treatment".*
A curious consequence of river reaeration was the finding of
a sharp increase in the biological oxygen demand just downstream from the
aerators. This rise is felt to be a good sign as it appears to be
accelerating the nitrogenous oxygen demand. It is best that this demand
be exerted as close to the aerators as possible rather than further
downstream.
* Third Annual Progress Report, "Oxygen Regeneration of Polluted Rivers",
Sept. 15, 1969, Water Resources Research Institute, Rutgers University,
New Brunswick, New Jersey.
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The Fairfax County Water Authority has uaed water aeration
in its water supply, thereby eliminating a taste and odor problem and
drastically reducing treatment costs. In 1969, the Water Authority
started investigating methods for improving the raw-water quality in
its Occoquan Reservoir by the elimination of existing eutrophic
conditions. In order to eliminate thermal stratification and improve
the raw-water quality, the authority decided that a system which would
induce turnover would achieve the desired results. The contract cost
for furnishing tubing and compressors for this system was $35,000.
The project has resulted in retarded eutrophication, elimina-
tion of anaerobic conditions and hydrogen sulfide generation, reduction
in chlorine demand and activated carbon needed in the treatment process,
removal of some manganese, improved water quality and uniformity of
temperature.*
The project costs expect to be recovered in four years, based
on the savings of chlorine alone. The project expects to reduce the
chlorine requirements by $10,000/year. Elimination of electrical equip-
ment damage in the power-generating room at the base of the dam from
hydrogen sulfide is also expected to save considerable money.
Thus, many project costs can be recovered and aeration may
be an economic benefit rather than an economic burden.
*Eunpu, Floyd R., "Control of Reservoir Eutrophication", Journal of
American Water Works Association. April, 1973, pgs..268-274.
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