Mill River Dams Feasibility Study River/Mill River Dams FS Executive... · Mill River Dams...

Mill River Dams Feasibility Study River Restoration and Diadromous Fish Passage

January 31st, 2008 Prepared for: Massachusetts Riverways Program Riverways Program, DFG 251 Causeway St., Suite 400 Boston, MA 02114

3602 Atwood Avenue Suite 3 Madison, WI 53714

2007 Inter-Fluve Inc. Mill River Concept Report 5

1. Executive Summary

This study examined the feasibility of various fish passage and river restoration options for the three

downstream impoundments on the Mill River in Taunton, Massachusetts (Figure 1-1). We conclude that

fish passage and river restoration are feasible, and we offer concept level design options for alternatives at

each dam.

1.1. State Hospital Dam

The State Hospital Dam is an earthen fill dam with a concrete spillway (8 ft head) impounding a pond

area of approximately 5.2 acres. The impoundment contains a maximum of 30,000 cubic yards of

deposited sediment consisting primarily of sand.

No Action Alternative – As part of the study, we examined the implications of no action at each

structure. No action at the State Hospital Dam would result in continued riverine habitat degradation

through sediment deposition, organic material buildup, invasive plant proliferation, thermal pollution, and

concentration of nutrients and pollutants. These negative effects of dams are well documented in

numerous studies (Baxter 1977, Dauta et al. 1999, Petts 1984, Poole and Berman 2001, Schuman 1995,

Stanley et al. 2002, Ward and Stanford 1979, 1987). No action also results in continued selective removal

of fine material from the downstream reach, resulting in over-widening of the channel and

homogenization of in-stream habitats (Gray and Ward 1982, Ligon et al. 1995, Ward and Stanford 1983).

No action with regard to river restoration and fish passage will require continued dam inspection,

maintenance and eventual repair or replacement to keep the dam in compliance with Massachusetts

Department of Dam Safety standards. The cost of these activities is typically borne by the dam owner. All

dams continue to degrade, and without regular maintenance and repair, the risk of flooding due to dam

failure increases. No action results in continued liability risk to the dam owner and continued risk to

public safety (Graber et al. 2001).

Dam Removal Alternative – Removal of the State Hospital Dam is feasible and would fulfill the goals

of the project. Dam removal would result in passage for diadramous fish (alewife, blueback herring) and

other species (eg. American eel, amphibians), free flowing conditions, restored riparian and in-stream

habitat, lower water temperatures, increased dissolved oxygen concentrations and the reestablishment of

river dependent fish and wildlife (Bednarek, A. 2001, Calabro 2007, Maclin and Sicchio 1999). These

include lithophilic or gravel dependent spawning fish, mussels and other macroinvertebrates, as well as

riparian birds, amphibians, reptiles and small mammals. Dam removal would also reconnect the nutrient

flow of upstream and downstream reaches, allowing both fish and nutrients to pass from reach to reach.

Migrating fish, including alewife, blueback herring, eel and other species, would be able to move daily

Figure 1-1. Mill River in Taunton, MA showing the location of the project dams

State Hospital Dam

West Britannia Dam

Whittenton Pond Dam

Morey’s Bridge Dam


and seasonally through the reach to ensure access to optimal feeding and spawning habitat. Removal of

the State Hospital dam would also remove dam owner liability and public safety concerns by eliminating

potential risk of flooding due to dam failure.

Fish Passage Alternatives – Both a fish ladder and a nature-like bypass channel (Figure 1-2) are

feasible at the State Hospital site and both fulfill the fish passage goals of the project. Either approach

does not remove the dam owner’s liability, and does not improve the degraded condition of the upstream

channel. Affordable Denil and prefabricated Alaska steep pass fish ladders have been shown to be

successful in facilitating the migration of

diadramous migratory alosid species (eg. alewife,

blueback herring, American shad) in the northeast

(Haro et al. 1999, Kleinschmidt 2005, Quinn

1994). Such a ladder could be installed at the State

Hospital site, but the degraded raceway would

require stabilization or partial reconstruction to

provide the structural support necessary for a

ladder. At this site, fish may have a tendency to

bypass the fish ladder inlet and occupy the 60 feet

of rock riffle apron. It is possible to limit low flow

over the main spillway and divert or interrupt

higher flows to create more attraction in the

preferred downstream location. Any fish ladder

would require significant concrete work to repair the dam, stabilize the left bank raceway and manipulate

spillway flow patterns to ensure attraction. This concrete work could increase the cost of a ladder project

while not ensuring passage of all Mill River fish species.

Nature-like or natural bypass channels have been successful at allowing passage of a wide variety of

species (Eberstaller et al. 1998, FAO/DVWK 2002, Jungwirth et al 1998, Aerestrup et al 2003, Mader et

al. 1998). A natural bypass channel was deemed feasible given the existence of the left bank historic

sluiceway which would allow for bypass channel construction with minimal excavation. The gentle slope

afforded by this route allows for a cascading riffle and pool design that would mimic natural stream

conditions and allow for passage of both migratory species (eg. alewife, herring, adult American eel) and

resident species (pickerel, darters, elvers).

Figure 1-2 – Example of a nature-like fishway or bypass channel (photo L. Aadland)


1.2. West Britannia Dam

The West Britannia (Reed and Barton) Dam is 85 feet long with a structural height of 8.0 feet and a

hydraulic head of 4.0 feet. The dam is an earthen berm and masonry dam with a concrete cap masonry

spillway formerly impounding a pond area of approximately 8.23 acres. The dam is currently drawn down

and has no significant impounded water area. The impoundment contains a maximum range of 13,000 to

26,000 cubic yards of deposited sediment consisting primarily of sand.

No Action Alternative – Because of the lowered impoundment and current run-of-river condition at

the West Britannia Dam, no action does not have the same type of impacts as predicted for the State

Hospital Dam. No action at West Britannia will maintain the existing condition of the impoundment, and

the river conditions will remain relatively static. The dam will continue to block fish passage and will

continue to present a maintenance cost and liability due to the risk of flooding from dam failure. In

addition, the existing raceway (right bank) is a continued risk to the Reed and Barton mill buildings under

which it flows.

Structural repairs are recommended for the West Britannia Dam. No action will still require some

maintenance and repair to be financed by the dam owner.

Dam Removal Alternative – Removal of the West Britannia Dam would result in free flowing

conditions, restored riparian and in-stream habitat, increased dissolved oxygen concentrations and

reestablishment of riffle and pool dependent fish and wildlife. The reach is currently a deep, rectangular

wetland channel. Removal of the dam would result in a steeper channel slope and more natural

geomorphic function, including sediment movement, bar formation and riffle and pool development. Free

passage of migrating fish and wildlife would be assured. Removal of the West Britannia dam would

remove dam owner liability and public safety concerns by eliminating flooding due to dam failure or

water passing under the mill buildings.

Fish Passage Alternative – Three non-removal fish passage alternatives were considered at the West

Britannia site, rock ramp, fish ladder, and natural bypass channel. A rock ramp was deemed infeasible due

to the filling of the channel downstream of the dam and the potential hydraulic impacts to the downstream

bridge crossing. The flood capacity of the West Britannia Street bridge could potentially be reduced as

filling would need to extend under the bridge.

An Alaska steep-pass or Denil-type fish ladder is feasible at the site, and would accomplish

diadromous fish passage goals. A fish ladder could be installed along the left bank retaining wall. Any

fish ladder would require significant concrete and masonry work to repair the dam, stabilize the left bank


retaining wall and manipulate spillway flow patterns to ensure attraction. We recommend that any fish

ladder design at the West Britannia dam also consider specialized eel and elver passage ramps.

A natural bypass channel was also deemed feasible if it could be constructed on the left bank

floodplain area. With either fish ladder or natural bypass channel, the degraded condition of the upstream

river reach remains, as does the dam owner’s liability risk.

1.3. Whittenton Pond

The Whittenton Pond Dam is a 10 ft high concrete and timber structure temporarily stabilized by a

riprap spillway. The dam currently impounds a pond area of approximately 9.5 acres. The impoundment

is currently partially drawn down as a result of 2005 emergency repairs that lowered the head of the dam

to approximately 8 feet (Belisle 2006). The impoundment contains a maximum range of 1400 to 4,000

cubic yards of deposited sediment consisting primarily of sand.

No Action Alternative – No action at the Whittenton Pond Dam will maintain the existing degraded

river condition of the upstream reach, including continued sedimentation, littoral vegetation accumulation

and expansion, thermal pollution and nutrient loading. The stabilization measures taken in 2005 were

intended to be temporary, and movement of stones and degradation of the structure were noted in our

field effort. The dam will need to either be removed or rebuilt in the near future. In the meantime, the dam

will continue to block fish passage and will continue to present a maintenance cost and liability due to the

risk of downstream flooding from dam failure.

Dam Removal Alternative – Removal of the Whittenton Pond Dam would result in free flowing

conditions, restored fish passage, restored riparian and in-stream habitat, increased dissolved oxygen

concentrations and the reestablishment of riffle and pool dependent fish and wildlife. Removal of the

Whittenton Pond Dam would remove dam owner liability and public safety concerns related to flooding

from dam failure. Removal would result in a conversion of general ecological condition from a lentic or

lake environment to a lotic, or riverine environment. This would include a restored sinuous channel

roughly 50 feet wide with a riparian zone managed with natural and private landowner aesthetics in mind.

Fish Passage Alternative – Three non-removal fish passage alternatives were considered at the

Whittenton Pond site, including rock ramp, fish ladder, and natural bypass channel. A rock ramp was

deemed infeasible given the high cost versus benefit and the potential change in hydraulics at the

downstream bridge crossing. The fish ladder and natural bypass options are feasible at the site, but would

require rebuilding of the dam. Of the two alternatives, a fish ladder would be the most economical, but a

natural bypass channel would ensure passage of a wider variety of fish species. With any of these fish


passage alternatives, the degraded condition of the upstream river reach remains, as does the dam owner’s

liability risk.

Alternatives analysis tables

Full dam removal and alternative fish passage options were both found to be feasible at each of the

three study dams, with a range of associated feasibility level cost estimates. The following tables show the

alternatives considered at the three dams considered in the study, and the advantages and disadvantages of

each option. A more detailed discussion of restoration options is given in subsequent sections of this

document. Detailed cost estimates are included as Appendix A.

Table 1-1. State Hospital Dam – fish passage alternatives

Estimated costs* Advantages Disadvantages

Do Nothing

Repair - $250,000

Long term maintenance costs are variable

• No immediate cost • Maintain pond aesthetic

• Increased cost of repair with time • Persistent long-term risk/liability of

failure and subsequent flooding • Continued riverine habitat degradation • Continued water quality impacts - thermal

pollution, dissolved oxygen • Continued degraded sediment quality

Full Dam Removal

RECOMMENDED

$989,000 – assuming special handling of sediments

$546,000 – assuming no special handling

• Improved fish passage • Restored natural river processes • Reduced or stabilized contaminants • Restored floodplain wetlands • Improved water quality • Increased property value • Reduced public safety risk • Funding available for removal and

sediment management • Improved park land opportunity

• Short term construction disturbance • Cost of contaminated sediment requires

additional grant funding effort • Removal of sediment adds substantial

cost, particularly if special handling is required

Dam repair with fish passage bypass channel

$250,000 – repair

$224,800 – fish bypass

Total $474,000

• Improved fish passage • Maintained impoundment water

levels • Reduced public safety risk

• Cost of repair is generally not funded by outside sources (eg. State or Federal grants)

• Short term construction disturbance • Persistent long-term risk/liability of



*Estimates are rounded to the nearest thousand and include construction, engineering and permitting. Estimates for engineering, permitting, dewatering, site repair and maintenance are shared by both dam repair and fish passage elements.

Estimates are feasibility level. The actual cost of construction may vary depending on final project approach, heavy construction market cost fluctuations and other factors. Estimates do not include construction cost contingency..


Table 1-2. West Britannia Dam – fish passage alternatives

Estimated costs* Advantages Disadvantages

Do Nothing

Repair - $200,000

Long term maintenance costs are variable

• No immediate cost • Maintain pond aesthetic

• Increased cost of repair with time • Persistent long-term risk/liability of failure

and subsequent flooding • Continued riverine habitat degradation • Continued water quality impacts - thermal


Full Dam Removal

RECOMMENDED

$694,000 – assuming special handling of sediments

$452,000 – assuming no special handling of sediments


sediment management

• Short term disturbance of the west end of the parking lot area (left bank – Reed and Barton)

• Cost of contaminated sediment remediation requires additional grant funding effort

Dam repair with fish passage bypass channel

$200,000 – repair

$230,000 – fish bypass

Total $430,000


levels • Reduced public safety risk


• Short term construction disturbance • Persistent long-term risk/liability of failure



Dam repair with fish ladder

$200,000 – repair

$61,000 – Alaska steep pass fish ladder

Total $261,000


levels • Reduced public safety risk • Fish passage funding for ladders is

potentially available


• Short term construction disturbance • Persistent long-term risk/liability of failure




Estimates are feasibility level. The actual cost of construction may vary depending on final project approach, heavy construction market cost fluctuations and other factors.. Estimates do not include construction cost contingency.


Table 1-3. Whittenton Pond Dam – fish passage alternatives

Advantages Disadvantages

Do Nothing

Rebuild Dam

$1.5 Million

Long-term maintenance costs variable

• No immediate cost • Impoundment maintained at current level

restores some of the riparian zone

• Not a practical option given that repairs must be made to address public safety

• Wetlands filling over time • Short term construction disturbance • Persistent long-term risk/liability of



Full Dam Removal

RECOMMENDED

$927,000 – assuming contaminant removal

$564,000 – assuming no contaminant removal

Includes $50K for fire suppression improvements


sediment management • Potentially increased property frontage

• Lowered water levels (change in recreational and aesthetic features)

• Requires alternate fire suppression for the Mill area

• Cost of contaminated sediment requires additional grant funding effort

Dam replacement with fish bypass channel

$1,505,000 - dam reconstruction

$203,000 - bypass channel

Total $1,708,000

• Improved fish passage • Maintained impoundment water levels • Reduced public safety risk

• Cost may be prohibitive • May not be permittable • Long-term risk of failure and sudden

flooding remains • Wetlands filling over time • Degraded habitat • Water quality impacts - thermal pollution,

dissolved oxygen • Slow release of contaminants

Dam replacement with fish ladder

$1,505,000 - dam reconstruction

$69,000 - fish ladder installation

Total $1,574,000

• Improved fish passage • Maintained impoundment water levels • Reduced public safety risk

• Cost may be prohibitive • May not be permittable • Short term construction disturbance • Persistent long-term risk/liability of

failure and subsequent flooding


Estimates are feasibility level. The actual cost of construction may vary depending on final project approach, heavy construction market cost fluctuations and other factors. Estimates do not include construction cost contingency.

Mill River Dam Removal Photosimulations

State Hospital Dam, West Britannia Dam, and Whittenton Mill Pond Dam

Note: these photosimulations were created to give people an idea of what the Mill River could look like at the dam sites if the dams are removed. These are not designs or engineering plans; they are conceptual only.

State Hospital Dam, State Hospital Dam, Taunton, MATaunton, MA

State Hospital Dam removal State Hospital Dam removal simulation, Taunton, MAsimulation, Taunton, MA

West Britannia Dam, Taunton, MA

West Britannia Dam removal simulation #1, Taunton, MA

West Britannia Dam removal simulation #2, Taunton, MA

WhittentonWhittenton Mill Pond Mill Pond Dam, Taunton, MADam, Taunton, MA

WhittentonWhittenton Mill Pond Mill Pond Dam removal simulation Dam removal simulation #1, Taunton, MA#1, Taunton, MA

WhittentonWhittenton Mill Pond Mill Pond Dam removal simulation Dam removal simulation #2, Taunton, MA#2, Taunton, MA

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