Montsweag Brook Restoration Project

The project received broad support from environmental, state, and federal agencies, including National Oceanic and Atmospheric Administration (NOAA), USDA Natural Resources Conservation Service (NRCS), American Rivers, The Nature Conservancy, the Gulf of Maine Council on the Marine Environment (GOMC), and the Maine Natural Resource Conservation Program (MNRCP).  The Davis Conservation Foundation supported the educational component of the project.

Project Update April 2012

Since the Lower Montsweag Brook Dam was removed,  Chewonki has been continuing to monitor the lower watershed for a variety of parameters indicative of habitat restoration, including:

  • Surveying to track changes in stream bed alignment and configuration
  • Fish and macroinvertebrate presence
  • Water quality
  • Visual changes via regular photographs at select locations
  • Vegetation growth in the previously flooded area

As evidenced by the vegetation sampling and as shown on the photos below, there has been tremendous plant growth in the former ponded area.  Chewonki has done a good amount of active seeding in the area (started prior to dam removal) but we strongly suspect that the majority of the plant growth is from seed that was laying dormant in the submerged soils and sediments of the pond.  Semiannual site inspections required by the U.S. Army Corps of Engineers have shown that the vast majority of surface soils in the area have been stabilized, and that erosion is now primarily limited to that expected from the small side tributaries that flow into the lower watershed.

Montsweag River FlowWhile results of water quality sampling (e.g., increased dissolved oxygen) prove the evident return of lower Montsweag Brook to free-flowing conditions, we have yet to observe the presence of alewives or brook trout upstream of the former dam location.  The other target fish species of the restoration project, American eel, are abundant and taking advantage of the improved upstream (and downstream) passage.  As with most of our other parameters, fish passage is monitored in multiple events each year; Chewonki plans to sample for fish in the late spring with the help of Maine’s Inland Fisheries and Wildlife (IF&W) and researchers from the University of Southern Maine.

With financial support from the Davis Conservation Foundation, Chewonki is also leveraging the project for education.  Students from Chewonki Semester School have performed grain size analyses, macroinvertebrate sampling, and supported fish sampling efforts (even campers have gotten involved!).  Students from Wiscasset Middle School have been doing field science in the former ponded area, studying changes along one of the larger tributaries to the brook.  Students from Wiscasset High School and Morse High School have also supported the long-term monitoring.  And Chewonki is certainly fortunate to have high-quality surveying help from a Dartmouth College geomorphologist.

Scroll down to see images of the project, including a map of the lower watershed, before and after shots of the site, and some monitoring photos.  Don’t miss the two amazing time-lapse videos of the dam removal, or the project overview video that summarizes the work.

Montsweag River“Dam removal has become a very important tool in our efforts to bring back fishery resources to the Gulf of Maine. We try to get fish back to their natal streams where they can spawn and return to the ocean. Dams have been a critical factor in the reduction of the natural species that are inhabiting these streams.” — John Catena, Northeast Regional Supervisor for the NOAA Restoration Center

“There is no single better way to restore habitat quicker and more effectively than removing a dam. The United States has removed more than 830 dams over the last few decades.” — Brian Graber, fluvial geomorphologist and water resources engineer, American Rivers

Dam 7Primary goals of the project are to restore riparian habitat and re-establish fish passage in lower Montsweag Brook in Wiscasset and Woolwich.  The project is designed to benefit target fish species including alewives, sea-run brook trout, and American eel.

Dam 1
The dam site before removal and during draw-down of the pond.
Dam 2
Former Chewonki Head Naturalist Lynne Flaccus conducts stream monitoring.

Dam 3

Dam 4

Dam 3

Dam 5

Montsweag Brook Lower DamBefore its removal, Lower Montsweag Brook Dam was the tallest water diversion structure in New England scheduled for removal. The impoundment flooded approximately 20 acres of riparian habitat and acted as a complete barrier to passage of native and diadromous fish.

Montsweag Brook Restoration Project Update
(posted on August 3, 2010)

The Wiscasset Planning Board unanimously approved site plan and shoreland zoning permits for the removal of the Lower Montsweag Brook.

We are looking forward with excitement to working with local schoolchildren to monitor the return of native fish to the Montsweag Brook.  This will be a wonderful hands-on science project right here in our own back yard. Chewonki has already started including visits to Montsweag Dam in its summer nature programs (see pictures at right).

(posted on May 10, 2010)
The project team is currently preparing federal, state, and local permits for dam removal and site restoration, which is planned for implementation this summer. Shoreland Zoning Permits will be submitted to the Planning Boards of Wiscasset and Woolwich. Public hearings for the project will likely be held in June.

Drawdown of the impoundment is scheduled to begin in mid- to late-May in order to inspect the upstream face of the dam and to begin revegetation of the area currently submerged. Chewonki will seed exposed sediments to reduce erosion and to control growth of invasive plant species. During the drawdown and seeding, visitors should avoid crossing over exposed sediments.

The public can access the dam area via Chewonki’s easement, which is located approximately 200 ft south of Maine Yankee’s gate and the pullout on Rte 1 (an abandoned dirt road leads to the downstream side of the dam). A property buffer around the impoundment and upstream on the Wiscasset side of the brook has been surveyed and posted by USDA Natural Resources Conservation Service (NRCS), the federal agency that will hold a permanent conservation easement for protection of the area. While signage states ‘private property’, public access is allowed. Public should avoid trespassing on Maine Yankee land and other private property in the area. Chewonki plans to construct a public trail along the easement corridor within the next several years.

We anticipate that bids for the demolition and site restoration work will be solicited in the next two months. During dam removal this summer, public access to the vicinity of the dam will be limited for safety reasons. Demolition activities will be scheduled to coincide with the low stream flow period of late summer. With a structural height of over 30 feet, Lower Montsweag Brook Dam represents the tallest water diversion structure in New England scheduled for removal.

As part of the stream restoration efforts, Chewonki is planning a long-term monitoring program that will involve local students and teachers in hands-on field science. A website will be developed to document and analyze restoration progress, including parameters such as fish passage and water quality.

The Montsweag Brook Restoration Project has received significant financial support from a variety of federal and state agencies, in addition to Maine Yankee, who supplied initial funding for the feasibility study. Key project partners include:
• Gulf of Maine Council/NOAA Habitat Restoration Program
• USDA Natural Resource Conservation Service
• Maine Natural Resource Conservation Program
• American Rivers/NOAA Community-Based Restoration Program

Montsweag Dam, East Side

Public Meeting Held
A public meeting was held at Chewonki on November 4, 2009 to discuss the Montsweag Brook Restoration project and feasibility study results. Notes of this meeting can be downloaded at right.

Montsweag Brook Restoration Project Description
Montsweag Brook is a coastal stream that drains into Montsweag Estuary, on the west side of Chewonki Neck. The brook is a minor tributary to the Back River (Sheepscot River system), originating from a 10.5 square mile watershed in the towns of Wiscasset, Woolwich, and Dresden. In 1968, Maine Yankee Atomic Power Company built a concrete dam on lower Montsweag Brook to supply emergency water for their nuclear facility on Bailey Point. As part of the 2008 Natural Resources Damages Restoration Plan and Settlement Agreement (NRDAR) between Maine Yankee and the State of Maine, Chewonki was given ownership of the lower dam and an easement on the Wiscasset side of the brook that stretches 2 miles upstream to another, smaller dam (currently owned by Central Maine Power). The impoundment created by the lower dam is 0.8 miles long and floods about 20 acres of riparian habitat. The dam acts as a complete barrier to the movement of fish species that need access to both saltwater and fresh water.

The NRDAR set aside funding for evaluation of re-establishing fish passage on lower Montsweag Brook. In Spring 2009, Stantec Consulting, Inc., of Topsham (ME), began a feasibility study, including a thorough assessment of the site conditions and evaluations of several different alternatives for restoring fish passage and riverine habitat. Results of the feasibility study indicate that dam removal is the least expensive and most effective approach for restoring fish passage and the natural riparian conditions upstream of the dam. Installation of a fish ladder was deemed too expensive and impractical due to the height of the dam and the relatively low and variable seasonal flows in the brook.

A baseline assessment of fish species in the brook established the presence of river herring at the downstream toe of the dam, indicating that dam removal and habitat restoration would be beneficial to these fish. Other target species identified by the assessment include brook trout, rainbow smelt, and American eel. Within the impoundment, several species of exotic, piscivorous fish (e.g., black crappie, chain pickerel) were caught. Other data collected show that the impoundment significantly alters water quality, especially in the summer months when water temperatures rise and dissolved oxygen levels drop dramatically.

In July 2009, during field activities for the feasibility study, several American eels were observed in small pools on the rock outcroppings that abut the west side of the dam (see photo). Apparently these juvenile eels had made the climb up the rock ledge during high water then were stranded from going further up as flow over the dam decreased. American eels are the only ‘catadromous’ fish in North America. The term catadromous refers to fish born in the ocean that mature in fresh water and return to the ocean to spawn. Further information about American eels can be found at

The Montsweag Brook Restoration Project has received significant financial support from a variety of federal and state agencies, in addition to Maine Yankee, who supplied initial funding for the feasibility study. Key project partners include:
• Gulf of Maine Council/NOAA Habitat Restoration Program
• USDA Natural Resource Conservation Service
• Maine Natural Resource Conservation Program
• American Rivers/NOAA Community-Based Restoration Program

Chewonki is also pleased to have support of the following organizations:
• The Nature Conservancy
• Maine Rivers
• Sheepscot River Watershed Council
• Sheepscot Valley Conservation Association
• The Coastal Conservation Association

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