LIHI Certificate #182 - Bonny Eagle Project, Maine

Project Name Bonny Eagle
LIHI Certificate No. 182
LIHI Certificate Term April 2, 2021 – April 1, 2031
Owner Brookfield White Pine Hydro, LLC, a subsidiary of Brookfield Renewable Energy Group
State Maine
Location Between River Miles 26 and 32.6, Saco River
Installed Capacity 7.2 MW
Average Annual Generation 39,067 MWh
Facility Type Intermittent peaking, seasonal run of river
FERC No. P-2529 issued in 1998, expires 01/31/2038

The Bonny Eagle Project is located in York and Cumberland Counties on the Saco River in Maine. The project’s dams and generating station are located in the towns of Hollis and Standish with the tailrace extending into the town of Buxton. The impoundment is located in Hollis, Standish, and Limington. Bonny Eagle is the fifth-most upstream project of seven hydroelectric facilities on the main stem of the Saco River, including the Cataract Project (LIHI #169). The project initially commenced operations in 1955.

The project consists of a 350-foot-long diversion dam, a 164-foot-long dam (constituting the intake) and two earth embankments on the main river channel, a powerhouse containing six horizontal-shaft Francis turbine/generating units with a total installed capacity of 7.2 MW, a 347-acre impoundment and appurtenant facilities. The diversion dam is located at the so called “New River Channel” while the intake and earth dikes are situated in a narrow gorge on the main river channel; a relatively large island (Bonny Eagle Island) separates the two channels. The dams create a riverine impoundment extending approximately 6.6 miles upstream and a bypassed reach approximately 0.7 miles long. Eight penstock entrances are located in the intake with 3/8-inch bar steel trashracks with 2-inch clear spacing. Six of the penstocks serve the main turbine/generator units (the other two are retired). The powerhouse is about 35 feet downstream from the intake. The tailwater is generally partially backwatered by the downstream West Buxton Project impoundment.

The project operates as an intermittent peaking facility with seasonal run-of-river operations. From April 1 through June 30, the project is operated in a run-of-river mode with a 1-foot fluctuation from the normal full pond and a minimum bypass reach flow of 25 cfs. From July 1 through September 30, a fluctuation of 4.5 feet from normal full pond is allowed with a total minimum flow including at least 25 cfs in the bypass reach, of 400 cfs. From October 1 through November 15, the same reservoir fluctuation is allowed but a total minimum flow of 600 cfs is required, inclusive of the 25-cfs minimum bypass reach flow. For the remainder of the year, the 4.5-foot fluctuation from full pond is authorized, with a 250-cfs minimum flow including the 25-cfs minimum bypass reach flow.

Waters within the project reach are designated as Class A, best suited for aquatic biota habitat and primary contact recreation. Maine Department of Environmental Protection has confirmed that the project does not impact water quality and no impairments are present in the project reach.

The Saco River is host to diadromous fish species including American eel, Atlantic salmon, American shad, alewife, blueback herring, rainbow smelt, Atlantic tomcod, mummichog, threespine stickleback, ninespine stickleback, and striped bass. Only Atlantic salmon, alewife, and American shad have been noted in the project vicinity.

The project provides downstream passage primarily for Atlantic salmon smolts and upstream passage facilities for American eel. An upstream eel ladder is operated from June 1 through September 30. The downstream fish bypass, a top-drop gate passing 200 cfs, is located at the powerhouse in the existing log sluice which leads to a chute into the tailrace with 3-inch spaced trashracks. It is typically open from April 1 through December 31, as conditions allow.

The project lands consist of 45 acres. A wetlands enhancement and protection plan was implemented providing measures for revegetation of disturbed areas within the 100-foot buffer strip around the wetlands, discontinuing leases for agricultural uses within the buffer zone, installing fencing on areas within the project boundary, and ongoing monitoring. The riparian areas along the river are heavily vegetated and not prone to erosion.

Threatened or endangered species potentially present in the project vicinity include the small whorled pogonia, Northern long-eared bat, small-footed bat, and Blanding’s turtle. No critical habitat was identified in the project area by US Fish and Wildlife Service for the pogonia or long-eared bat, which along with the other bat species, are potentially transient in the area. Blanding’s turtle is potentially present in the nearby wetlands and Maine Department of Inland Fisheries and Wildlife has recommended consultation before undertaking any activities that could disturb that habitat.

The Bonny Eagle powerhouse and dam structures are eligible for inclusion on the National Register of Historic Places. The facility represents a period of early hydropower generation development. Notably, the powerhouse interior is unaltered and contains a collection of early twentieth century hydropower generating machinery.

Recreational resources at the project include a picnic and day use area along with a canoe portage trail. Public access is provided free of charge.

Compliance Status

The Certificate includes the following facility-specific conditions:

  • Condition 1: The facility Owner shall update the Minimum Flow and Pond Level Monitoring Plan to reflect current conditions and monitoring features at the Project in consultation with the USF&WS, MDEP, and MDIF&W, and shall submit it to FERC for approval upon receipt of resource agency approval. The Owner shall provide LIHI with a copy of the submittal cover letter to FERC and a copy of the FERC’s approval of the Plan.
  • Condition 2; In annual compliance statements, the facility Owner shall provide status updates on the proposed decommissioning of the Bar Mills Project as it relates to potential changes in upstream or downstream fish passage requirements or implementation schedule at Bonny Eagle. If the Fish Passage Agreement is amended during the term of LIHI Certification, the owner shall provide a copy of the amendment(s) to LIHI with a summary of changes related to Bonny Eagle.
  • Condition 3: In annual compliance statements, the facility Owner shall provide documentation of consultation with MDIF&W and implementation of any recommended mitigation measures, should any ground disturbance of the Project wetlands or onsite tree removal be needed. This consultation is required due to the possible presence of protected bats and the endangered Blanding’s turtle.

2023: No material changes or compliance issues were identified. The project remains in compliance based on the annual review.  For Condition 1, the project reported the plan is under review by resource agencies. For Condition 2, the project reported agency consultation if ongoing for Bar Mills decommissioning with a surrender application and draft study plan expected in 2023.  For Condition 3, the project reported no activity.

2022: No material changes or compliance issues were identified. The project remains in compliance based on the annual review.  For Condition 1, the project reported the plan is currently being revised. For Condition 2, the project reported agency consultation if ongoing for Bar Mills decommissioning.  For Condition 3, the project reported receiving a FERC variance for out-of-season tree cutting and a state waterways permit for installation of a battery energy storage system expected to be completed in 2022.

2021: Annual reporting for the current Certificate has not yet taken effect.

Certification History

January 1, 2022: The LIHI Certificate term has been extended in accordance with Revision 2.05 of the LIHI 2nd Edition Certification Handbook issued January 1, 2022. Refer to the facility table above for the new term.

August 19, 2021: The Low Impact Hydropower Institute has issued a final decision on the certification of the Bonny Eagle Project located on the Saco River in Maine. The 30-day appeal window closed on August 18, 2021 and no appeals were filed. Therefore, the decision to certify the project is now final. The certificate term is April 2, 2021 through April 1, 2026.

July 19, 2021: The Low Impact Hydropower Institute (LIHI) has preliminarily approved the Bonny Eagle Project for a 5-year term of Low Impact Certification.

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 with “Bonny Eagle Project” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 1167 Massachusetts Ave, Office 407, 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 August 18, 2021. The full application and reviewer’s report are available below.

If no appeal requests are received and the decision becomes final, the Certification term for the Project will be April 2, 2021 through April 1, 2026.

January 11, 2021: The Low Impact Hydropower Institute has received a complete application for Low Impact Certification of the Bonny Eagle 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. Please review the program and criteria in LIHI’s revised Handbook and then review the Project’s application materials 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 with “Bonny Eagle 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 March 12, 2021 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.


2021 Certification