LIHI Certificate #137 – Eel Weir Project, Maine

The Eel Weir Project is located the Presumpscot River in Cumberland County, Maine. The hydroelectric project is situated at the outlet of Sebago Lake in the towns of Windham and Standish, Maine. The Presumpscot River originates from this point and extends roughly 25 miles southeast to the Atlantic Ocean at Casco Bay. The project headgates were installed in the mid-1800s at the outlet of Sebago Lake and the generating facilities were later commissioned in 1903 by the Presumpscot Electric Company, a subsidiary of S.D. Warren (later renamed Sappi North America, Inc.). There are six hydroelectric facilities on the Presumpscot River between Sebago Lake and the Atlantic Ocean in Portland, Maine. Downstream projects include North Gorham (LIHI #129), Dundee (LIHI #138), Gambo (LIHI #139), Little Falls (LIHI #140), and Mallison Falls (#141).

The project includes: a 1,350-foot-long dam, a 900-foot-long, non-overflow concrete retaining wall and earth-fill east embankment; a 115-foot-long, 22-foot-high stone masonry and concrete spillway; a 35-foot-long, 17-foot-wide stone masonry and concrete river gatehouse with five 6.4-foot-high, 4.8-foot-wide wooden gates; a 260-foot-long stone masonry and earth-fill west embankment; a 90-foot-long fish screen with ¾-inch clear-bar spacing located immediately upstream of the canal intake gatehouse; a 40-foot-long, 19-foot-high canal waste gate structure with three 17-foot-wide, 11-foot-high steel slide gates; a minimum flow gate located within each steel slide gate; a powerhouse containing three horizontal Hercules turbines with a total installed capacity of 1.8 MW; and a 3.5-mile-long, 11-kilovolt transmission line.

The project is operated in a store-and-release mode and impounds a 28,771-acre reservoir. The flow regime requires that releases from the project protect aquatic resources and minimize erosion along the shoreline, while providing adequate conditions for recreation and boating. The project provides seasonal minimum flows: 125 cfs from April 1 - October 31 and 75 cfs from November 1 - March 31. Minimum flows year-round are required to be 270 cfs and 408 cfs between June 1 - September 30 to provide the downstream Gambo Dam adequate flows for meeting dissolved oxygen requirements. The flow regime was developed in consultation with US Fish and Wildlife Service and endorsed by Maine Department of Environmental Protection (MDEP).

Project Name Eel Weir
LIHI Certificate No. 137
LIHI Certificate Term September 5, 2017 - September 4, 2022
Owner Sappi North America, Inc.
State Maine
Location Located at Windham & Gorham, Cumberland Counties River mile 25 on the Presumpscot River
Installed Capacity 1.8 MW
Average Annual Generation 12,300 MWH
Facility Type store-and-release
FERC No. P-2984 issued 2015, expires 2055

Waters within the project reach are designated Class A in the bypass and tailrace, and Class GPA in the impoundment. The project minimum flow standards help mitigate any impacts to downstream dissolved oxygen levels. Monitoring of dissolved oxygen is conducted at downstream Gambo Project impoundment. The results are compiled annually and submitted to MDEP which confirms that the project attains water quality standards of the Presumpscot River.

The Presumpscot River supports a managed fishery upstream of the project. Maine Department of Inland Fisheries and Wildlife (MDIFW) does not support upstream passage facilities at the project as it may impact the success of the fishery and ecology of the lake ecosystem. This position is supported by USFWS and Maine Department of Marine Resources (MDMR). The project operates a 21-foot vertical helical style ramp to provide upstream passage for American eel. Monitoring results of the passage facility are submitted annually to MDMR and MDIFW.

Project lands encompass 31,423 acres most of which consists primarily of flowage rights along the impoundment (Sebago Lake) and limited lands around project facilities. Lands surrounding the lake are developed, while lands downstream of the dam are mostly undeveloped. A land use and recreation management plan details measures and information on recreational features around Sebago Lake, project land management, and aesthetic character preservation. The plan was developed in consultation with MDIFW, MDEP, and the town of Windham.

Threatened and endangered species potentially within project vicinity include: Northern Long-eared bat, Eastern Small-footed Bat, Little Brown Bat, Brook Floater, Least Bittern, Upland Sandpiper, Eastern Box Turtle, Spotted Turtle. Activities with the potential to affect the listed species include removal of large trees that may provide roosting habitat for the bats, exposure/dewatering of the Brook Floater mussel during significant, prolonged impoundment drawdowns, loss of or fragmentation of habitat due to development for the Least Bittern, Upland Sandpiper, and Spotted Turtle, direct taking of Box Turtles for pets. The project owner expressed that none of these activities are planned at the project.

Historic resources in the project vicinity include the Eel Weir dam, canal, forebay, powerhouse, and tailrace, all National Register eligible as a Hydropower Historic District. The project must consult with the State Historic Preservation Office and any affected tribes before any ground-disturbing activities, construction, and any activity that may affect historic properties around the project. A pre-historic archaeologist is conducting a Phase 0 archaeological report in in the project area which is expected to be complete in 2021.

Recreational resources at the project include fishing access points and boat access. Sappi is completing a 2nd round of monitoring for capacity usage information at the State’s Songo River facility in CY 2021.


 Certification History

March 23, 2018 – The 30-day appeal window for the preliminary certification decision of the Eel Weir Hydroelectric Project closed on March 1, 2018 with no appeals to the decision received. The decision is therefore final and Eel Weir is LIHI Certificate #137. The Certificate term will be September 5, 2017 – September 4, 2022. The certificate includes the following condition:

  • Condition 1. The Owner shall update LIHI on the following activities and provide requested documentation in the annual LIHI compliance statement:
    1. Satisfied 2019. Status of completion of releasing the 125 cfs minimum flow to the bypass reach, expected to begin April 1, 2019, in accordance with the current agency approvals.
    2. The status of downstream eel passage testing. Once testing is completed, the Owner shall forward to LIHI a copy of the final report, agency comments on the report, any agency recommendations made as a result of the testing, and any plans and schedule for any needed modifications to downstream passage facilities or measures.
    3. Receipt of formal agency notification by USFWS or any state resource agency that conditions have changed and it is appropriate that upstream and/or downstream passage for anadromous species is installed at the Project;
    4. A summary of any consultation with MIF&W and/or USFWS related to state or federally listed species identified as possibly occurring at the site that could be impacted by construction activities or non-routine operations or maintenance activities. A summary of the relevant triggering activities and the measures implemented during the year to protect such species shall also be provided.
    5. Status of completion of the Phase 0 archeological studies by the 2021 deadline specified in the HPMP; and
    6. Status of completion of the report on improvements for public access to Sebago Lake by the June 30, 2022 deadline, including comments and concurrence of resource agencies of the report findings.

January 30, 2018 – On January 24, 2018, the Low Impact Hydropower Institute (LIHI) preliminarily approved Low Impact Certification for the Eel Weir project.

This decision is preliminary pending the 30-day appeal window. Only those who commented in the initial application 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 to comments@lowimpacthydro.orgRequests must be received by 5:00 pm Eastern time March 1, 2018.

September 7, 2017 – On September 7, 2017 the Low Impact Hydropower Institute (LIHI) received a complete application from S.D. Warren Company d/b/a Sappi North America.

LIHI is seeking comment on the Eel Weir application for certification. 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 “Eel Weir Project Comments” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 329 Massachusetts Avenue, Suite 2, Lexington, MA 02420.  Comments must be received at the Institute on or before 5 pm Eastern time on November 7, 2017 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.