Yarmouth Fishways and Dams FAQs


The Town of Yarmouth owns the Bridge Street dam and the East Elm Street dam. Both dams are in disrepair and technically obsolete, and neither dam has any purposeful use. Power production ceased at the Bridge Street dam prior to 2015. Both fishways—structures built to help fish over dams—are currently nonfunctional, beyond repair and by today’s standards poorly designed for migrating fish. In 2019 the Maine Department of Marine Resources notified the Town of Yarmouth that rehabilitating the current fishways would be a wasted effort due to their outdated technology and limited benefit to sea-run fish species.

Yarmouth Fishways

What are "fishways"?

A fishway is a structure built to facilitate fish movement over or around dams and other barriers. Fishways incorporate a series of pools that fish ascend by swimming against a current, with places to stop and rest along the way. The flow of water into a fishway is managed to provide optimal flows during periods of migration, and the flow out of a fishway is en­gineered to attract fish to the entrance. The ability of different fish to utilize a fishway varies, so modern fishways are carefully designed and managed to pass targeted species.

Where are the Royal River fishways?  

Yarmouth has two Denil fishways, which consist of a sloping rectangular concrete channel with closely spaced wooden baffles on the sides and bottom. The first fishway up from the harbor is on the Bridge St. dam. The second fishway is on the East Elm St. dam, about half a mile further upstream. Each is located on river right (facing downstream), and can be viewed from Royal River Park.

Are the Royal River fishways in Yarmouth functional?

No. The two Yarmouth fishways are currently inoperable, in disrepair, and have many functional deficiencies. A 2018 study concluded the fishways are a constraint on the long-term restoration of up & downstream passage for targeted fish (alewife, American eel, American shad, blueback herring, sea run brook trout, rainbow smelt, sea lamprey, striped bass) Inter-Fluve, 2018.  The Maine DMR (Department of Marine Resources) has notified the Town of Yarmouth that fishway repair and maintenance would be a wasted effort due to their dated technology and limitations (Maine DMR, 2019). The fishways were constructed nearly 50-years ago and designed based on knowledge that is obsolete. Since then, fishway technology has greatly improved. For many design and construction reasons, if the existing fishways were repaired, their capability to pass fish would be severely limited Inter-Fluve, 2018

Yarmouth fishways are not designed for all target fish types—for example, shad require a low flow rate and wider ramps since they migrate as a school. Although shad are good swimmers, they have lesser abilities than salmonoids (Passage of American Shad, 2012, Design of Fishways for Shad, 2002).

BRIDGE ST DAM FISHWAY - needs repairs and maintenance:

Does not meet design standards for shad 

Lacks juvenile eel passage (for spring up-stream migration)

Lacks intentional downstream fish passage 

Inadequately sized for expected run populations and resting pool areas

Provides insufficient attraction flow at fishway entrance

EAST ELM ST DAM FISHWAY - needs repairs and maintenance:

–Replacement of weirs, gates, trash racks & control structures is needed

Entrance is blocked with boulders & adjacent channel requires modification

Entrance configuration is very poor with water flowing across the entrance

–Stop log weir is in disrepair and blocked with debris, negating its use in managing flow

Outflow from the foundry by-pass channel forms a competing attractant flow

Does not meet the design standards for shad 

Lacks juvenile eel passage (for spring up-stream migration)

Lacks intentional downstream fish passage

Inadequately sized for anticipated run populations and for resting pool areas

Provides insufficient attraction flow at fishway entrance

Who built the fishways and why?

The Town of Yarmouth, working with the Maine Department of Marine Resources, constructed the Bridge St. fishway in 1974 and the East Elm St. fishway in 1979. The Town owns both dams. The fishways were retro-fitted onto the dams to allow native migratory fish such as alewife, blueback herring & shad to access critical spawning and rearing habitat as part of efforts to restore these fisheries in State waters and the Gulf of Maine. The fishways were also intended to benefit sea-run trout.

It is in the 1834 State legislative record that sea-run fish migrated up the Royal River. In 1834 a bill was introduced regulating the taking and management of sea run fish by North Yarmouth (Yarmouth split from North Yarmouth in 1849) residents and requiring fish passage at dams.  The bill was passed but functional fish passage was not enforced.

Who owns and is responsible for operating and maintaining the fishways? 

The fishways on both dams are owned by the Town of Yarmouth. Both fishways were constructed by the Maine Department of Marine Resources (DMR) in the mid-1970’s, under a leasing arrangement with the Town. Under the leases, DMR was responsible for operating and maintaining the fishways for a number of years. However, the DMR gave up its leases, and the Sparhawk Mill owners have given up their Bridge Street dam water and power generating rights. Therefore, the responsibility for maintaining and operating the fishways has reverted solely to the Town of Yarmouth.

Per Maine Statute –Title 12 Conservation, Chapter 925 Fish and Wildlife Management and Research, Section 12760 –the public has the right to petition the Department of Marine Resources and IFW (Inland Fisheries and Wildlife) Commissioners to hold a fishway proceedings. The Commissioners have the authority to require the dam owner to provide fish passage. The owner elects to either remove the dam or install fish passage. Where this Statute was recently employed on the Presumpscot River, the dam owner, SAPPI, elected to install fish passage. The dam owner is at significant financial risk (must pay for costly modifications to the constructed fishway) if the fish passage does not meet the required efficiency.

How much will it cost to improve or install effective fishways?

Due to design limitations, fishway improvement is not a viable option for restoring fish migration to and from Casco Bay and the Royal River watershed.  The fishways need to be replaced or the dams removed.  In Inter-Fluve, 2018, a fish passage consulting firm, developed preliminary cost estimates for functional fish passage at both dams.  Depending upon the style of fish passage, the 30-year life cycle cost, including construction and maintenance, ranged from $1.1 to $1.4-million per dam.  Based on recent fishway construction in Maine on a similar sized river, Trout Unlimited reported an estimated cost for construction alone would be approximately $1-million per each dam (Trout Unlimited, 2020b)Annual fishway maintenance costs of $16,000–$20,000 per year would continue indefinitely for as long as the dams exist, this is in addition to the expense of maintaining the dams themselves. 

Yarmouth Dams

Who owns the dams?

The Town of Yarmouth owns both the East Elm St. and Bridge St. dams. At the Bridge Street dam, the Town also owns the penstock (the large metal pipe) to the Sparhawk Mill and the inlet valve to the penstock (which controls the flow of water).

Are the dams functional?

Yes, the dams do hold back water and form water impoundments—with the Elm Street Dam slowing water flows, raising water levels and temperatures, and lowering dissolved oxygen levels on nearly a six-mile stretch of the river. However, both dams are in a state of disrepair with repairs suggested by various consultants and FERC (Federal Regulatory Commission).

Years ago the Bridge Street dam diverted water to Sparhawk Mill to generate hydropower, but as of 2015 (or earlier) power production ceased, and the owner has removed the power generating equipment and surrendered its operating license to FERC.

The last known use of the Elm Street dam, as noted in a 1959 Inland Fish and Wildlife fish habitat assessment report, was to flush chicken processing waste to the harbor from a plant located across the street from the history center.

What are the annual maintenance costs for the dams and the cost for dam removal?


A 2010 Stantec  engineering report for the Town of Yarmouth estimated the annual maintenance cost for each dam at $5,000 per year. In addition to that amount, while not analyzed in detail, the dams at that time were thought to each need several tens of thousands of dollars in immediate repairs.

The last available FERC inspection report from 2015 recommended a number of repairs to the Bridge Street dam and the penstock (FERC only inspects licensed power-producing dams). The non-power producing East Elm Street dam has not been inspected by FERC, but may fall under the oversight of Maine Emergency Management Agency.  

The Town budget in recent years has allocated $20,000 or more annually towards the dams, mostly for periodic removal of downed trees that float downriver and get hung up on the dams.


Based on recent dam removal costs of similar sized dams in Maine, the expected cost to remove Bridge Street and Elm Street dams is less than $300,000 each (reported by Trout Unlimited, 2020b). The Town of Yarmouth would be responsible for a portion of the cost of dam removal. NOAA, other government agencies and environmental foundations also provide grant funding for dam removal (but typically they do not fund fishway construction). The Royal River Alliance wishes to help minimize the burden of the cost of safe and responsible dam removal on the Town and on local businesses and property owners situated riverside and harbor-side. This could involve fundraising, grant-seeking, volunteerism and other means of project assistance.

Fish Restoration

Will sea-run fish return after dam removal?

Yes. When dams and barriers are removed, sea-run fish return—see success stories! The Royal River is a relatively small river and would not sustain huge runs. Sea run fish are naturally imprinted to return to where they were spawned. Some fish species wander more than others.  Over time, on their own, sea run fish, some species much sooner than others, will return to the Royal River. If humans place spawn or mature fish ready to spawn in the watershed, sea run fish will return within a handful of years.

Improving the river habitat and access to it will likely benefit species including American shad, alewives, blueback herring, sea-run trout and American eel. Restoring fish passage can benefit mammals and avian predators, such as egrets, otters, eagles, ospreys and loons. 

“Restoring the Royal River will likely support the federally listed threatened Atlantic Sturgeon and endangered Shortnose Sturgeon overwintering habitat for adults; and reproductive and nursery habitat for egg and juvenile life stages.” –US Army Corps of Engineers, 2020a.

What else would need to be done (in addition to dam-removal) to promote fish passage on the Royal River in Yarmouth?

In 2012, a small barrier in the side-channel bypass at the Royal River Middle Falls was removed (Bouchard, K, Portland Press Herald, 2012). In 2017, the U.S. Fish and Wildlife Service (USFWS) notified the Royal River Alliance that two new locations in the side-channel may hinder fish movement. The USFWS concluded a few days work in the side-channel would significantly improve fish passage at a relatively low cost (USFWS, 2017).

Are there any natural barriers to fish passage?

Yes. Far upstream below Bald Hill Road in New Gloucester, there are natural falls that have been identified as a natural barrier for sea-run fish.  With the removal of a small dam on Collyer Brook in Gray, and some minor modifications to an abandoned boulder dam that assists in forming Runaround Pond in Durham, 90% of the 141-square mile watershed would be available to sea-run fish (GZA GeoEnvironmental, 2018).  Currently, with the two dams in Yarmouth, essentially zero square miles are available for sea run fish.

If the dams were removed, how many sea-run fish might return to the watershed? 

Based on figures supplied by the U. S. Fish and Wildlife Service for the amount of river herring and shad habitat available in the watershed and accepted numbers of returning adult fish that amount of habitat would support, the Royal River Watershed could see approximately 62,000 river herring (alewives and blueback herring) and 29,000 American shad (Trout Unlimited, 2020a). This tracks reasonably well for river herring with what occurred when alewives were being stocked into the upper watershed: measured at 46,485 in 1984, estimated at 50,000 in 1981. 

Impact on Birds

How will birds be impacted by river restoration and the return of sea-run fish?

When dams and barriers are removed, sea-run fish return, which leads to a positive impact on the bird community. "Once the dams are removed, and the fish are moving more freely, birds like ospreys and eagles in particular, herons, all those other fish-eating birds move with the fish. They certainly take advantage of that more open system and benefit from it. There is more biomass through the whole length of the river, when the dams are taken out." —quote from Judy Camuso, Commissioner of Maine's Department of Inland Fisheries and Wildlife, 2021.


Do the dams hold back sediment from the harbor?

The same amount of sediment is transported down the river and into the harbor, river channel, and Casco Bay with or without dams (Stantec, 2010 and Field Geology Services, 2013). This is supported  by the lack of large areas of sediment deposition in the river channel.  However, more than 90% of the sediment is flushed to the bay and does not settle in the channel or harbor due to its small grain size—based on studies conducted by Stantec, 2013 and Woods Hole Group, 2010.

Some amount of sediment may be "stored" in the water impoundment behind each dam and may be transported a single time after a dam is removed. Roughly 143,000 cubic yards of material was removed during the 2015 harbor and channel dredge, which accumulated over 18 years (Portland Press Herald, 2015). 

The volume of sediment behind the Bridge Street dam is 4,200 cubic yards (plus an 800 CY contingency, Stantec, 2015)—only 3.5% of the amount removed during the last harbor and channel dredge (143,000 CY). The volume of sediment in the Elm Street dam impoundment is larger (the exact amount is unknown), and likely equivalent to no more than a few years of accumulation.

Will the harbor fill up with sediment after dam removal?

Following Elm Street dam removal, migration of sediment and short term bank erosion will occur within the river as it rebuilds its natural channel. However, long-term bank erosion in the impoundment is not expected to occur. Therefore, sediment production within the river will not significantly increase. In addition, there are limited amounts of sediment in the river for the first 3 miles upstream of the Elm Street dam. This section of the river has very large and deep holes (some 25 feet deep) that can trap sediment as the river reworks the channel over time. Taken together, dam removal is unlikely to significantly increase sediment transport and delivery to the harbor (Stantec, 2013 and Fields Geology Services, 2013). 

Marine clay soils form a large part of the Royal River watershed, resulting in the familiar chocolate brown water. We cannot alter this underlying geology. The Royal River harbor has been dredged periodically since the Civil War era and will continue to be dredged for as long as there is navigation in the harbor and river channel, with or without the dams.

In the absence of the dams, sea run fish are likely to return (as discussed above) to the Royal River. The presence of sea-run fish—like alewife, shade and river herring—in the river is  required for the freshwater mussel life cycle. (It's not surprising that many freshwater mussel species are at risk of extinction.)  Mussels filter silt, nutrients, bacteria, algae, toxins and other small particles from water, thus, keeping the water cleaner for other organisms and for recreation (Maine Department of Inland Fisheries and Wildlife).  Should freshwater mussels return robustly to the Royal River watershed they have the capability to significantly reduce the silt/clay size sediment in the water column that is transported downstream . 

Are there toxins in the dam sediment?

Elm Street Dam Impoundment: Sediment in the Royal River above the Elm Street dam was tested for toxic chemical contamination. The results showed minimal potential for risk to aquatic life (Stantec, 2013). 

Bridge Street Dam Impoundment: While one of ten sediment samples from the Bridge Street impoundment had PAH (polycyclic aromatic hydrocarbons) and mercury levels of concern, collectively the ten samples did not. These compounds were found in sediment adjacent to the 325-acre Yarmouth Village storm drain outlet and a storm water run-off site from the Rte. 1 overpass. The contaminants are largely from incomplete combustion of petroleum & wood, engine oil spillage and fossil-fuel-derived materials (i.e. coal tar sealant). The presence of PAH at this location will remain whether the dams remain or are removed due to continued storm water run-off. The Maine DEP confirmed Stantec’s conclusion that the sediment from the Bridge St. dam impoundment is clean overall and has minimal potential risk to aquatic life (Stantec, 2016). This conclusion allows dredged materials to be safely disposed of—at a reasonable cost—at a site designated in Casco Bay.

From all available data and from past harbor dredging experience, the contamination concentrations of impoundment sediments will not alter where the harbor dredge material is currently disposed, either for beneficial reuse or at the Portland Disposal Site—an ocean designated location beyond Halfway Rock. 

One location, the location with more than 10x the mercury than any other, is located well below the Bridge Street dam.  Dam removal or dam retention will not impact sediment transport at that downstream location. The mercury source is believed to be from ash from the former pulp and paper mill in Yarmouth.

In the absence of the dams, sea run fish are likely to return (as discussed above) to the Royal River. The presence of sea-run fish—like alewife, shade and river herring—in the river is  required for the freshwater mussel life cycle. (It's not surprising that many freshwater mussel species are at risk of extinction.)  Mussels filter silt, nutrients, bacteria, algae, toxins and other small particles from the water, thus, keeping the water cleaner for other organisms and for recreation (Maine Department of Inland Fisheries and Wildlife).  Should freshwater mussels return robustly to the Royal River watershed, they have the capability to significantly reduce the silt/clay size sediment in the water column that is transported downstream . 


How often does the harbor have to be dredged?

The middle of the harbor and the river channel out to Parker Point was designated a federal navigation channel in 1960. The US Army Corps of Engineers (USACE) dredges that portion of the harbor and channel. The navigation channel was last dredged by the USACE in 2014/2015. The prior USACE dredging was in 1997 (US Army Corps of Engineers, 2020b).   

Users of the harbor and channel would prefer more frequent dredging. The Yarmouth marina owners dredge their slip areas every 5 to 10 years, which are not part of the federal navigation channel.

Who is responsible for the harbor and river channel dredging?

The US Army Corps of Engineers (USACE) is responsible for monitoring the need for dredging the numerous federal navigation channels and for prioritizing and budgeting those needs in its annual funding requests to Congress.  Congress is responsible for appropriating funds to dredge the federal navigation channels.  There is political jockeying for priority in project funding as there is never enough annual  funding to cover all needs.  This makes predicting the dredging timetable difficult.  Once the funds have been appropriated, however, the USACE is responsible for contracting and managing the dredging.

Who dredges the harbor near the marinas?

The Yarmouth marinas or the Town of Yarmouth (at the public boat ramp) are responsible for dredging in the river, as it is not within the federal navigation channel designation.

Recreation on the Royal River

Will the reflecting pool disappear if the Bridge Street dam is removed?

No. Sonar bathymetry work done for the Town of Yarmouth in 2013 indicates that a reflecting pool will remain after the Bridge Street dam is removed, although  the pool will be shallower and narrower than the existing pool. This was confirmed during a voluntary Bridge Street dam drawdown in 2010.  Upstream of the Beth Conden walking bridge a now submerged water fall/tumble will be exposed with a new separate pool formed above that tumble extending to the base of Third Falls (Stantec, 2010).

Will recreational use of the Royal River change with dam removal?

The removal of the Elm Street dam would lower the water level of the six-mile impoundment behind the dam (Stantec , 2010). Instead of flat water, the river would look and act more like a river. The canoe put-in at the Yarmouth History Center would need to be moved upstream because the water would be flowing toward a cascade. However, Elm Street dam removal will also result in significant beneficial impacts in the upstream impoundment like expanded fishing of stocked fish with the addition of sea-run fish species and new opportunities to observe diverse wildlife species that target migratory fish, such as eagles, osprey, river otters and kingfisher. The removal of the Bridge Street dam would likely improve fishing along the pathway up to the Elm Street dam (Maine Rivers, 2013). There’s very little recreation in the river now between the two dams.

How far will the water level drop in the river if the Elm Street dam is removed?

At the river’s annual median flow rate, the water level would drop from approximately 71-feet to 65.4-feet. Therefore, the water level will drop approximately 5.6-feet in the Elm Street dam impoundment should the entire Elm Street dam be removed (Stantec, 2013).

Stantec conducted a bathymetry survey (to determine the water depth) from the Bridge Street Dam to the Route 9 bridge (Stantec, 2010).  This study found an underwater rock ridge that spans the river behind the History Center on E. Elm Street.  The rock ridge forms a natural dam similar to what is naturally present at Grist Mill Falls. If the Elm Street dam, which is about 10-feet tall, were to be entirely removed, the History Center rock ridge would limit the lowering of the water elevation upstream of the ridge to about 5.6-feet.  

Dam Removal Permitting Process

What will occur during the permitting process?

Two permits will be required in addition to any the Town may require of itself —  a USACE General permit and a Maine DEP NRPA permit.  Both processes require public notification and public comment. Any member of the public may request in writing a public hearing be held with reasons submitted.  It's up to the Maine DEP and USACE discretion if a public hearing is granted.  During the permitting process the USACE or Maine DEP may request more sediment sampling. The permitting process requires an estimate of the amount of sediment that will be transported at dam removal and how much if a 100-year storm event occurred shortly after dam removal prior to vegetation becoming established.

Who does the Royal River Alliance represent?

RRA members are your neighbors. We are residents of Yarmouth and surrounding communities who care about the health of the Royal River. We are teachers, engineers, architects, retirees, volunteers, etc.  We do not represent other conservation groups. They do a fine job representing themselves and we are happy to work alongside any organizations with common goals.

Click for shortened version of Yarmouth Fishway & Dam FAQs RRA-2020


Field Geology Services, 2013.  Potential Impacts of Dam Removal on Sediment Production and Sediment Transport on the Royal River, ME.  Commissioned by Stantec.

GZA GeoEnvironmental, 2018. Royal River Fish Passage Studies Summary Report. Prepared for The Nature Conservancy. 

lnter-Fluve, 2018. Royal River Fishway Assessment and Cost Analysis Report. Commissioned by The Nature Conservancy.

Maine Rivers, 2013. Royal River Restoration Project, Yarmouth, Maine: Summary of Recreational Changes Associated with Dam Removal & River Restoration.

Stantec Consulting Services, 2010.  Fisheries & Aquatic Habitat Restoration Feasibility Study. Commissioned by the Town of Yarmouth. 

Stantec Consulting Services, 2013.  Royal River Restoration Project : Phase II Analysis and Reporting. Commissioned by the Town of Yarmouth. 

Stantec Consulting Services, 2015. Estimated Sediment Volume: Bridge St. Dam Impoundment. Commissioned by the Town of Yarmouth. 

Stantec Consulting Services, 2016.  Sediment Analysis Bridge Street Dam Impoundment, Royal River Yarmouth, ME.  Prepared for the Nature Conservancy.

Trout Unlimited, 2020a. 2020 Estimate of Shad and River Herring Potential for the Royal River Watershed, April, 2020.

Trout Unlimited, 2020b. Estimated costs of Dam Removal and Fishway Construction on the Royal River, Yarmouth, Maine.

US Army Corps of Engineers, 2020a.  Federal Interest Determination: Royal River, Yarmouth, Maine 206 Aquatic Ecosystem Restoration.  At the request of the Town of Yarmouth.

US Army Corps of Engineers, 2020b.  Federal Interest Determination: Royal River, Yarmouth, Maine 1135 Modifications for the Improvement for the Environment.  At the request of the Town of Yarmouth.

US Fish and Wildlife Service, 2017.  Assessment of the Royal River. Letter to the Royal River Alliance.

Woods Hole Group, 2010.  Laboratory Testing in Support of Environmental Assessment, sampling, and biological testing- Royal River Federal Navigation Project, Royal River, Yarmouth, Maine.  Prepared for the US Army Corps of Engineers.

Updated: 11/09/20