LEARNING & EXPLORING
Fishways in the Eightmile River Watershed - A Guide
Linda Bireley - Eightmile Coordinating Committee, Lyme
Fishways at dams are key components of enhancing our protected watershed spaces. They restore the passages between freshwater habitat and the ocean for migratory fish like Atlantic salmon (Salmo salar), American shad (Alosa sapidissima), alewife (Alosa pseudoharengus), blueback herring (Alosa aestivalis), sea lamprey (Petromyzon marinus), sea-run brown trout (Salmo trutta) and American eel (Anguilla rostrata). Many of these species access freshwater habitat to reproduce and their young use the habitat as a nursery area to feed and grow until they return to the ocean. Eels are the exception to this pattern. They reproduce in the ocean and migrate to freshwater to grow to maturity before they return to the open ocean to spawn. Fishways also expand the habitat available to non-migratory fish such as yellow perch, white suckers and catfish. When more habitat is available, more fish can reproduce and survive. More fish improve the “food chain” so more kinds of fish, birds and mammals can prosper with restored prey. Fish stocks in the oceans can prosper as well.
There are two fishways in the Eightmile River Watershed (see map), both in Lyme. These fishways are the “highways home” for migratory fish and the “back roads” for resident fish in the Watershed. The Moulson Pond Fishway provides a pathway around the first barrier in the Watershed, the Rathbun Dam, which is about 3 miles from the mouth of the River. The Ed Bills Pond Fishway provides a pathway around the second barrier, the Ed Bill’s Dam, which is on the East Branch of the Eightmile River about half a mile upstream of its confluence with the West Branch of the Eightmile. Upstream of these dams, the Eightmile River Watershed has high quality habitat essential for the survival of both migratory and resident fish species. The Lyme Land Conservation Trust (LLCT), with support from the Connecticut Department of Environmental Projection (CT DEP), operates both fishways April through June for spawning adult fish and again in October - November for spawning adult salmon and emigrating juvenile fish. The LLCT also maintains the fishways.
Moulson Pond Fishway
The Moulson Pond Fishway is located on private property and is not open to the public. It was constructed in 1997 through a partnership of interested parties. The LLCT and the Silvio Conte Fish & Wildlife Refuge of the U.S. Fish & Wildlife Service provided staff support and funding. The CT DEP/Inland Fisheries Division provided staff support and materials. The CT River Watershed Council, the Coastal Conservation Association of Connecticut, and private donors provided additional funding.
The Moulson Pond Fishway was designed to accommodate a water supply system that supported mills during the Eighteenth, Nineteenth, and Twentieth centuries and the aesthetic andpreservationist concerns of several private landowners. The Fishway makes use of a pre-existing millrace and tailrace (see schematic below). Water flows from the head pond through a gate that, until June 2007, opened up from the bottom of the millrace. The water continues in the m
illrace, which passes under a private residence and extends approximately 200 feet downstream to another former mill and now contains a small hydroelectric generating station. About halfway down the millrace, a concrete structure constructed in the side of the millrace provides the openings for water flow and fish passage. Upstream fish passage is provided through several sections of Alaskan steep pass. Attraction water is provided through a secondary weir that passes water down a buried pipe; this also provides a route for downstream passage of young salmon and herring. Water flowing down the steep pass and through the buried pipe converges at the head of an excavated, semi-natural channel (photo below). From there, water flows through a semi-natural section into an old abandoned tailrace, which, in turn, leads to the Eightmile River below the dam.
Since the first dam at this location was built in the early Eighteenth century, enough alewife and blueback (collectively river herring) spawned and used nursery habitat in the stretch of river between Hamburg Cove and the dam to maintain their populations. Thus when the fishway was first opened on March 30, 1998, river herring began using it to expand their migration from the Atlantic Ocean through Long Island Sound, up the Connecticut River, through Hamburg Cove to spawning grounds in the Eightmile River Watershed.
Since 1998, dedicated volunteers have monitored the fishway daily between early April and late June and estimated the fish using the fishway. The results of the monitoring effort suggested two things. First, the numbers of herring using the fishway were declining, which was similar to the decline in herring seen all along theAtlantic Coast. Second, that when the hydro unit was drawing water to generate electricity, the fish had difficulty negotiating the increased water velocity through the submerged opening of the water control gate.
By 2004 water leaking from the millrace around the concrete structure had undermined the steep pass, and the LLCT was concerned that the side of the millrace could fail, damage the fishway and private property, and interrupt the effort to restore migratory fish to the Eightmile River Watershed.
To ensure the continued effectiveness of the Moulson Pond Fishway to pass fish, the LLCT and the CT DEP decided to repair the leaks and replace the water control gate. The leaks were repaired in September 2005 by injecting foam similar to Great Stuff ® into the unconsolidated soil along the bank of the millrace. When the foam solidified the leaks stopped.
The water control gate that opened up from the bottom was replaced in June 2007 with a pivoting “butterfly valve” that left the entire water column available for both water flow and fish passage. With this gate, water velocities will be lower and the fish will not have to swim next to the bottom to negotiate their migration upstream. For the first time in 2007 we used an underwater camera to record fish passing through the water control gate between 7 pm and midnight every night. We did this because we wanted to determine how fish reacted to different water velocities and we manipulated the velocities by having the gate open all the way and half way. We haven’t viewed all the video tapes, however when I checked the tapes to make sure there was a viewable image, I noted that on several dates, when no fish were seen by volunteer monitors in the fishway during the day, several fish were recorded passing through the gate. This suggests that we have been underestimating the number of fish using the fishway. We plan to repeat this next year and would like to have the underwater camera image available realtime on the internet.
The repairs and the gate replacement were funded by: Long Island Sound Study and National Fish and Wildlife Foundation with funding support from US Fish and Wildlife Service, National Oceanic and Atmospheric Administration, and the Shell Marine Habitat Program, Long Island Sound Fund administered by the CT DEP and individual donors. Volunteers also provided services to the effort.
Ed Bill’s Pond Fishway
Ed Bill’s Pond Fishway is located on private property, through an easement donated to the LLCT by the late June Maynard. It can easily be seen from the bridge on Salem Road that crosses the East Branch of the Eightmile River (see photos below and top of story). This bridge is about 0.2 mi from Rt. 156/Hamburg Rd. The fishway was constructed in 2000 with support from CT DEP, CT River Watershed Council, Corporate Wetlands Restoration Partnership - Boehringer & Ingelheim, Fish America Foundation in cooperation with National Oceanographic and Atmospheric Administration, LLCT, Pfizer, Inc., private donors, Town of Lyme, US Fish & Wildlife Service, US Environmental Protection Agency and the USDA, Natural Resource Conservation Service.
The first few years that the Ed Bill’s Pond fishway operated we didn’t expect to see any spring migrating river herring, shad or salmon. This was not surprising because several years would be required for fish populations to expand into the reaches of the Eightmile River between the Moulson Pond Fishway and this one. To “jump start” the migratory fish restoration CT DEP fisheries biologists stocked several hundred herring caught in Latimer Brook into Ed Bill’s Pond annually between 2001 and 2006; they also transferred shad into the Pond from the Connecticut River. School children in the area have been raising and releasing salmon fry into the Eightmile River for several years as well. Occasionally 
volunteer monitors wouldobserve some of these herring or shad in the pond above the dam. Volunteers also reported seeing trout jumping into the falls at the base of the dam and an increasing number of fish eating birds inthe area of Ed Bill’s Pond. During the 2007 migratory season the CT DEP fisheries biologists were unable to transplant any fish into Ed Bill’s Pond. Volunteers were delighted to observe herring in Ed Bill’s Pond this year – these fish are the first known to have reached this pond on their own since the early Eighteenth century!
For more information or to volunteer to monitor these fishways or to set up the Moulson Pond Fish camera for internet access please contact LindaBiota "at" Comcast "dot" net.