LIHI Certificate #147 – Brooklyn Dam Project, New Hampshire

Project Name Brooklyn Dam
LIHI Certificate No. 147
LIHI Certificate Term June 4, 2018 – June 3, 2028
Owner Ampersand Brooklyn Dam Hydro LLC
State New Hampshire
Location River mile 3.2 on the Upper Ammonoosuc River in Northumberland, Coos County
Installed Capacity 600 KW
Average Annual Generation 2,405 MWh
Facility Type run-of-river
FERC No. P-13806 exempt 2015

The Brooklyn Dam Project is located on the lower section of the Upper Ammonoosuc River in Northumberland, Coos County, NH. The project lies between the Red Dam, located about 0.8 miles upstream, and the Weston Hydropower Project, located about 0.7 miles downstream.

The Upper Ammonoosuc River is separate from the Ammonoosuc River of the White Mountains. The Upper Ammonoosuc River discharges to the upper Connecticut River approximately 3.2 miles downstream of Brooklyn Dam. The upstream Red Dam originally was a second development of the FERC license that included the Brooklyn Dam Project. The Red Dam is no longer used for power production and is not part of the current FERC license exemption for the Project.

The dam was constructed in 1912 to provide hydro-mechanical power to local paper mills. In 1930, hydroelectric generation facilities were installed at the project to provide power to the Groveton Paper Mill and it operated as a hydropower facility until 1969 when the turbines and generators were removed. It was purchased by Ampersand Brooklyn Dam Hydro LLC in 2013 for redevelopment and re-entered service in December 2015.

The project includes: a dam, floodgate structure, forebay, tailrace, powerhouse, two turbines, and transmission equipment.

The project dam is a 120-foot-long, 14-foot-high timber crib dam with a 43-foot-long floodgate structure containing four 6.9-foot-wide, 10-foot-high floodgates. The Project includes a 100-foot-long, 45-foot-wide forebay, with three 15.2-foot-wide, 15.5-foot-high trash racks with 1-inch clear-bar spacing. There is an approximate 100-foot-long bypass from where water spills over the dam to where it merges with the tailrace.

When operating, water passes through the trashracks and forebay structure into the brick and concrete powerhouse which contains two Kaplan turbine generating units with an installed capacity of 0.6 MW. Turbines discharge to a 48-foot-long, 45-foot-wide tailrace. Power is transmitted through an underground transmission line connecting the powerhouse electrical panel to three single-phase transformers. An above-ground transmission line transmits power from the transformers to the regional distribution grid.

The project operates in run-of-river mode and impounds a 26-acre reservoir. At flows less than 33 cfs, the Project will not operate, and all flow passes over the spillway. At flows between 33 cfs and 630 cfs (the maximum operating capacity), the project will operate, and no flow will pass over the spillway. At flows greater than 630 cfs, the project will operate at its maximum capacity with excess flows passing over the spillway. This flow regime was developed with and approved by US Fish and Wildlife Service (USFWS), New Hampshire Fish and Game (NHFG), and New Hampshire Department of Environmental Services (NHDES).

Waters within the project reach are designated Class B and impaired for mercury, primarily due to atmospheric deposition. Class B waters are suitable aquatic habitat for aquatic biota and wildlife, as well as primary contact recreation. Water quality sampling was conducted at the project in collaboration with NHDES and USFWS to determine if the project was adversely impacting water quality in the river. The sampling results concluded that dissolved oxygen, temperature, pH, total phosphorus, and chlorophyll-a were all within state standards.

Historically, Atlantic salmon were able to migrate upstream to the project reach of the Upper Ammonoosuc River. However, the construction of dams downstream on the Connecticut River in the mid-19th century precluded access for migratory species. The project reach is primarily managed as a warm-water fishery, hosting fish species including brown bullhead, common sucker, yellow perch, common shiner, chain pickerel, and blacknose dace. NHFG also stocks brook, brown, and rainbow trout in the river occasionally. Trashracks with 1-inch spacing and an approach velocity of less than 2 fps mitigate entrainment as recommended by USFWS.

The project lands consist of less than four acres. No lands in the project area have significant ecological value and surrounding lands are mostly developed with a mix of industrial, vacant land, and some residential areas.

Threatened or endangered species potentially present in the project vicinity include the Northern long-eared bat and Canada lynx. Based on consultation with the New Hampshire Natural Heritage Bureau, project operations are not expected to impact these species. No individuals are known to occur at the project site and no critical habitat exists in the project area, though both species are known to exist in Coos County.

No historic properties exist in the project area. The Groveton Bridge is in the vicinity of the project and is eligible for National Register of Historic Places and there was historical use of the area by the Abenaki Tribe. Consultation with the New Hampshire State Historic Preservation Officer is required for any ground disturbing or construction activities at the project.

Recreational resources at the project include a canoe portage and recreational fishing access. Public access is provided free of charge.

Compliance Status

The Certificate includes the following facility-specific conditions:

  • Modified in 2022 to reduce reporting to annually from quarterly. Condition 1: In annual compliance statements, the facility Owner shall submit information sufficient to confirm run-of-river operations, adherence to impoundment refill rates, and related agency communications. Any requests made by the Owner for modifications to operations or refill rates, agency approvals of such modifications, copies of notifications to FERC and NHDES of any OCMP deviations, and copies of annual OCMP deviation reports to NHDES shall also be provided to LIHI with the compliance statements.
  • Condition 2: The facility Owner shall submit to LIHI the NHDES review and comment on the 2018 water quality monitoring results within 60 days of receipt. The Owner shall consult with NHDES and USF&WS on the need for additional sampling in 2019 and 2020 and file with LIHI the results of that consultation by July 31, 2019. If additional sampling is not required by NHDES and USF&WS, the Owner should evaluate the need to file with FERC a request for amendment to the exemption to remove the requirement for additional sampling and, if applicable, provide a copy of the request and any subsequent FERC approval to LIHI when available. If minimum flows into the bypass reach are required, LIHI shall be provided with all relevant information and agency communications within 60 days of receipt.


2021:  For Condition 1, the project submitted quarterly statements to LIHI. For Condition 2, the project indicated no response from NHDES on the monitoring reports. The project remains in compliance based on the annual review.

2020: For Condition 1, the project submitted quarterly statements to LIHI. For Condition 2, the project reported conducting additional water quality monitoring in 2019. The project remains in compliance based on the annual review.

2019: For Condition 1, the project submitted quarterly statements to LIHI. For Condition 2, the project submitted monitoring results to NHDES. The project remains in compliance based on the annual review.

2018: 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.

February 12, 2019: The decision to certify the Brooklyn Dam Hydroelectric Project is final. No appeals were received during the appeal period which closed on February 10, 2019. The certification term for the Project is from June 4, 2018 through June 3, 2023.

January 11, 2019: On January 10, 2019, the Low Impact Hydropower Institute (LIHI) preliminarily approved Low Impact Certification for the Brooklyn Dam Hydroelectric Project.

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 “Brooklyn Dam Hydroelectric Project” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 329 Massachusetts Ave, Suite 2, Lexington, MA 02420. 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 February 10, 2019.  The full application and reviewers report are available below.

If no appeal requests are received and the decision becomes final, the Certification term for the Project (pending LIHI #147) will be June 4, 2018 through June 3, 2023.

October 26, 2017: On October 26, 2017, the Low Impact Hydropower Institute (LIHI) received a complete application from Ampersand Brooklyn Dam Hydro LLC for the Low Impact Certification of the Brooklyn Dam Hydroelectric Project, FERC Exempt No. P-13806, located on the Upper Ammonoosuc River, near Northumberland, in Coos County, New Hampshire.

LIHI is seeking comment on the Brooklyn Dam 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 with “Brooklyn Dam 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 December 26, 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.


2018 Certification