LIHI Certificate #195 - South Berwick Project, New Hampshire/Maine

Project Name South Berwick
LIHI Certificate No. 195
LIHI Certificate Term December 8, 2022 – December 7, 2032
Owner Green Mountain Power Corporation
State New Hampshire and Maine
Location River Mile 0 on the Salmon Falls River
Installed Capacity 1.2 MW
Average Annual Generation 3,164 MWh
Facility Type Run of river
FERC No. P-11163, issued in 1997, expiring November 30, 2037

The South Berwick Project is located in Maine and New Hampshire on the Salmon Falls River and lies at the intersection of the Town of South Berwick in York County, Maine and the Town of Rollinsford in Strafford County, New Hampshire. The majority of the project’s infrastructure including the intake, penstocks, and powerhouse are located in South Berwick. The right abutment of the dam is located in Rollinsford.

The Salmon Falls River is a coastal tributary to the Piscataqua River and drains a watershed of 220 square miles. The South Berwick dam divides the riverine and tidal portions of the river and is the first dam on the Salmon Falls River. The river reach below the project to the coast is tidally influenced. There are no dams or structures downstream between the Project to the mouth of the river. Approximately 3.9 miles downstream, the Salmon Falls River joins the Cocheco River to form the confluence of the Piscataqua River.

The South Berwick dam was originally constructed in 1831. In 1923, the existing powerhouse was constructed. In the late 1990s the project was redeveloped into its current configuration and operation.

The Project’s facilities include:

  • an 18-foot-high and 290-foot-long concrete gravity dam with 2-foot-high flashboards;
  • an integral 220-foot-long spillway section;
  • an impoundment with a gross volume of 641 acre-feet with a surface area of 58 acres at the normal pond elevation of 24.95 feet msl and negligible useable storage volume;
  • an intake structure on the left (eastern) abutment of the dam;
  • three headgates that feed three, 8-foot diameter, 70-foot-long penstocks;
  • trashracks with a 1-inch clear spacing oriented at a 45-degree angle to the river
    channel and flow;
  • an upstream and downstream fish passage facility;
  • two 4-foot by 4-foot sluice gates used as flood gates and for lowering the headpond
    levels;
  • an 85-foot-long by 30-foot-wide concrete and brick powerhouse;
  • three vertical Francis turbine-generator units with a total installed capacity of 1.2
    MW, switch gear, and unit control system; and
  • appurtenant facilities.

The project operates in run-of-river mode and provides a minimum flow of 44 cfs to address water quality issues, and run-of-river operations ensure protection of aquatic and riparian habitat. Pond elevation in the headpond is regulated via a Programmable Logic Controller to ensure headpond levels stay consistent as river levels vary. A computerized system enables data collection and storage to support monitoring and reporting requirements. This flow regime was developed in consultation with Maine Department of Environmental Protection, US Fish and Wildlife Service, and New Hampshire Fish and Game Department (NHFGD).

Waters within the project reach are designated Category 4A which delineates estuarine and marine waters that are impaired or threatened for one or more designated uses but do not require development of a TMDL. In the early 2000s, the project conducted several years of water quality monitoring in the project tailwaters. Upon completion, Maine Department of Environmental Protection supported findings that the project does not contribute or cause non-attainment of water quality standards.

The Salmon Falls River has historically hosted several diadromous species including American shad, American eel, and river herring. Atlantic salmon runs were heavily impacted such that by 1750 (prior to the dam’s construction), these runs were sufficiently disrupted by older upstream dams, overfishing, and sawdust pollution that salmon no longer returned to the Salmon Falls River for spawning. The project tailrace is heavily fished in the spring when diadromous fish are present. Operation of the fish passage facilities is coordinated annually with NHFGD. The project owner works closely with NHFGD and assists with installation of fish counting equipment at the fish ladder, as well as manual counts at the eel ladder.

The fish passage facility was constructed between the left (eastern) abutment of the dam and the intake structure in 2002. The 4-foot wide Denil style fish ladder is constructed of steel and concrete and is designed to operate in either upstream or downstream passage mode. The entrance to the fish ladder is in the Project’s tailrace adjacent to the discharge of turbine-generator Unit No. 3. The fish ladder exit, which also serves as the downstream bypass entrance, is located to the right (western) side of the angled trashracks. When operated as a downstream passage facility, the baffles are removed from the upper section of the fish ladder and stoplogs are used to seal off the middle and lower section of the ladder to redirect flow and out-migrating fish into a plunge pool in the tailrace. Upstream passage for American eel is also provided at the Project, via an eel ramp located at the base of the dam. Juvenile American eel typically utilize the Project’s eel ladder from late spring to early fall. Other resident fish species in the Salmon Falls River include yellow perch, largemouth bass, bluegill, golden shiner, brown bullhead, and redfin pickerel. Additionally, the habitat can support fluvial-dependent fish such as white sucker and fallfish. There are several non-native species at the project, including several species of bass that were introduced via stocking programs.

The project lands consist of roughly 7 acres. Lands in the project vicinity are primarily undeveloped forested riverbanks with some scattered development. The tailrace area is considered intertidal estuarine habitat due to tidal influence. Run-of-river operations ensure protection of project shorelines.

Threatened or endangered species potentially present in the project vicinity include the Northern long-eared bat, Atlantic sturgeon, shortnose sturgeon, bald eagle, Atlantic mudwort, eastern grasswort, great bur-reed, pygmy-weed, and seaside brookwood. No critical habitat for the listed species has been identified in the project area. Suitable habitat may be found in the project vicinity though run-of-river operations minimize the potential for impacts on these species. Vegetation management at the project occurs outside any areas of concern and is not expected to impact listed species.

No cultural or historic resources have been identified in the project area with concurrence from the Maine State Historic Preservation Commission, stating during relicensing that “there were no sites of historical, architectural, or archeological significance that would be affected by the continued operation of the South Berwick Project.” Although not within the project boundary, the historic Counting House sits at the corner of the Salmon Falls River and Liberty Street in South Berwick. The Counting House was listed on the National Register of Historic Places in 1975. The Counting House is not operated or maintained by the project.

Recreational resources at the project include boating access at the Foundry Street boat launch in the impoundment, bank fishing along the impoundment at the boat launch and below the project, and canoeing on the downstream reach of the river. The east bank near the powerhouse also affords river access. Public access is provided free of charge.


Certification History

April 18, 2023: The Low Impact Hydropower Institute has issued a final decision on the certification of the South Berwick Hydroelectric Project. The certification term is December 8, 2022 through December 7, 2032.

March 13, 2023:  The Low Impact Hydropower Institute (LIHI) preliminarily approved Low Impact Certification for the South Berwick Hydroelectric Project (pending LIHI #195).  The application and review report are found below.

This decision is preliminary pending the 30-day appeal window. Only those who commented on the initial application during the 60-day comment period are eligible to file an appeal. Such appeal needs to include an explanation as to how the Project does not meet the LIHI criteria. Appeal requests can be submitted by email to comments@lowimpacthydro.org with “South Berwick Project” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 1167 Massachusetts Ave, Arlington, MA 02476. All requests will be posted to the website. The applicant will have an opportunity to respond and any response will also be posted. Requests must be received by 5 pm Eastern time on April 12, 2023. If no appeal requests are received the certification term will be December 8, 2022 through December 7, 2032.

December 8, 2022: The Low Impact Hydropower Institute has received a complete application for Low Impact Certification of the South Berwick Hydroelectric Project.  LIHI is seeking public comment on this application.  Specifically, we are interested in knowing whether you think the Project meets the LIHI Low Impact Certification Criteria, as revised in the 2nd Edition Handbook.  The Project’s application materials can be found below.

Comments that are directly tied to specific LIHI criteria (flows, water quality, fish passage, etc.) will be most helpful, but all comments will be considered.  Comments may be submitted to the Institute by e-mail at comments@lowimpacthydro.org with “South Berwick Project Comments” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 1167 Massachusetts Avenue, Arlington, MA 02476.  Comments must be received on or before 5 pm Eastern time on February 6, 2023 to be considered.  All comments will be posted to the web site and the applicant will have an opportunity to respond.  Any response will also be posted.


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