Parker River Anadromous Fish Restoration (Main Street Dam #4)
The goal of this project was to restore and improve anadromous fish runs in the Parker River. The Essex County Greenbelt Association (ECGA) led the project, with cooperation and support from NOAA/NMFS, MA Department of Marine Fisheries, USFWS, the Parker River Clean Water Association, Essex County Sportsmen Association, and others interested in the restoration of anadromous fish in the Parker River. In 1996, an assessment of Parker River determined that an existing fishway at dam #4 was inhibiting fish passage. The cost to repair and maintain this fishway, which was constructed in 1935, would have exceeded $100,000. Instead of repairing the fishway, the ECGA proposed the purchase and installation of an Alaskan Steep Pass fish ladder, and received a grant through FAF to support the work. The Steep Pass is an aluminum rectangular conduit that is inserted into the top of a dam and sits on the streambed approximately 20 feet below the dam. A stop log device at the top of the fish ladder is adjusted to regulate flow through the fishway during migration of alewives. The installation of the new Steep Pass will play a substantial role in helping anadromous fish make a come back in the Parker River.
A 1973-74 study, undertaken by the University of MA, estimated the herring population of Parker River to be in excess of 30,000 fish. By 1997, estimates of the herring population had declined to about 6,000 fish, attributed partially to the deterioration and inefficient design of the six fishways on the river. Another 1998 report determined the # 4 dam to be the least functional passage facility of the entire system. In addition to poor design and extreme deterioration of the fishway, other problems included poor access, and complete lack of passage for juveniles during downstream migration. The installation of the new Steep Pass fish ladder will alleviate these problems and provide improved passage for adult and juvenile fish. And the new ladder, located on the roadside of the dam and easily visible and accessible, provides greatly improved opportunities for education and volunteer monitoring and maintenance.
In November of 2000 preparations began to install the Steep Pass. First obstructions were cleared from the installation area and eighty sandbags were placed above the dam at the site of the dam cut. Gravel was cleared from the upstream side of the dam to allow room for the concrete saw to operate, and two sections of the new fish ladder were preassembled off-site. On November 18, the first cut was made in the dam with a concrete saw, at the appropriate angle for fishway placement. Later, the brackets were bolted to the top of the dam at the cut. A wooden frame, made of 6" x 6" pressure treated lumber, was built at the top of the ladder and bolted to the dam and the fish ladder (the wooden frame holds the fish ladder in place, directs water into the top of the fish ladder rather than over the dam, and also creates a framework for the stop log boards). Finally, a small amount of concrete was put in the cracks between the fish ladder and the dam cut, to control leakage. Since its installations, the fish ladder has received regular inspections and adjustments. Because of this and other restoration efforts on the Parker River, the alewife population is expected to return to historic levels and other anadromous species should benefit as well.