LIHI Certificate #166 - Quinebaug-Five Mile Pond Project, Connecticut

Project Name Quinebaug – Five Mile Pond
LIHI Certification No.
LIHI Certification Term
June 21, 2019 – June 20, 2029
Owner Quinebaug Associates, LLC, a subsidiary of (Gravity Renewables Inc.
State Connecticut
Location Quinebaug: River mile 26.2 on the Quinebaug River.

Five Mile Pond: River mile 0.2 on the Five Mile River.

Installed Capacity Total: 2.59 MW

Quinebaug: 2.24 MW

Five Mile Pond: 0.35 MW

Average Annual Generation Total: 7,945 MWh

Quinebaug: 6,925 MWh

Five Mile Pond: 1,020 MWh

Facility Type Run of river
FERC No. P-5062 issued 1987, expires 2027

The Quinebaug – Five Mile Pond Project is located at the confluence of the Five Mile River and Quinebaug River in the Towns of Brooklyn and Killingly in Windham County, Connecticut. The two developments, Quinebaug and Five Mile Pond are located in close proximity, but on different rivers, and authorized under the same FERC license. The project was built and started operation in 1990 by Diamond Power Corporation at dams originally constructed around 1885. The Five-Mile Pond development is the first and only hydropower facility on the Five Mile River though several non-powered dams are located upstream of the project including the Old Daniels Dam, Ballouville Dam, and two unnamed dams. The Quinebaug development has several dams upstream of it, some used for flood control, mills, or hydropower. These include the Rogers Dam, Cargill Falls, Putnam (LIHI #3), MSC, and the US Army Corps of Engineers’ West Thompson flood control dam located on the French River just upstream of its confluence with the Quinebaug River. Downstream of the development are the Aspinook (Wyre Wind), Tunnel Dam, and Greenville dams.

  • Quinebaug Development: The development consists of the Rojak dam, approximately 250 feet long with a 30-foot-wide, 7-foot deep and 900-foot-long power canal intake structure toward the right and spillway on the left (looking downstream). The dam is a stone masonry gravity structure with an overflow spillway section approximately 130 ft long. An axial flow propeller turbine is located inside a steel pressure case on the non-overflow section of the dam and provides minimum flows into the 0.3-mile bypassed reach. Immediately upstream of the powerhouse is a canal and an approximately 200-foot-long reinforced concrete overflow/auxiliary spillway. The powerhouse contains two Kaplan/bulb turbines with a combined capacity of 2.24 MW.
  • Five Mile Pond Development: The Five Mile Pond Development consists of a stone masonry gravity dam approximately 135 feet long and 16.5 feet high, with a 100-foot-long spillway. There is a spillway on the left (looking downstream) and a canal intake structure toward the right which is approximately 30 feet wide, 12 feet deep and 280 feet long. The dam creates a bypassed reach, approximately 158 feet long. Immediately upstream of the powerhouse is a canal overflow spillway. The spillway is concrete lined and approximately 80 ft long. The powerhouse contains a single double regulated Kaplan turbine with a capacity of 0.35 MW.
  • Quinebaug: The reservoir created by the dam is approximately 85 acres. The development is operated in instantaneous run-of-river mode therefore, no reservoir storage is utilized for power generation. The project provides a minimum flow released into the bypassed reach of 77 cfs, or inflow if less.
  • Five Mile Pond: The reservoir created by the dam is approximately 65 acres. The development is operated in instantaneous run-of-river mode with no storage. The project provides a minimum bypass flow of 15 cfs, or inflow if less, which is released to the bypass reach through a notch in the flashboards.

The flow regimes were developed via recommendation from US Fish and Wildlife Service to maintain suitable aquatic habitat. Run-of-river operations are maintained using a Programmable Logic Controller to adjust gate settings appropriately.

The Quinebaug River waters are designated as Class B. These waters are managed for aquatic and wildlife habitat, agricultural/industrial water supply, and recreation activities. Some upstream and downstream areas within the reach of the Quinebaug development have been classified as non-supporting for aquatic life and/or recreation due to E. coli. According to the Connecticut Department of Energy and Environmental Protection (CTDEEP), hydropower operations are not listed as a potential source of this impairment. As for the Five Mile River, the waters are not listed as impaired and consultation with CTDEEP concluded that the project operations had no adverse impacts on water quality.

Downstream dams create barriers to fish passage at both developments. Ongoing restoration efforts are targeted at American shad, blueback herring, and alewife, all of which were once common in the Thames River Basin of which the Quinebaug River is a part. Spawning runs of the species were extirpated in the mid-to-late 1800s due to the construction of dams. Spawning and nursing habitat for river herring, shad, sea lamprey, and American eel remains above the dams. Fish passage provisions are currently being developed at the downstream Wyre Wind Project which, upon completion, will make the Quinebaug project the next barrier to upstream fish passage. A cascade at the mouth of the Five Mile River downstream of the Five Mile Pond damforms a natural historic barrier to anadromous species passage but provisions for future passage for American eel have been identified. Trashracks with 3-inch spacing at the Quinebaug development and 2-inch spacing at the Five Mile Pond development mitigate potential for entrainment and impingement along with the low approach velocity, below the standard recommended 2 feet/second. Five Mile Pond also allows for downstream passage via the minimum flow notch in the spillway flashboards, leading to the bypassed reach.

The project lands consist of roughly 4 acres. Half of these lands are tree or brush covered while the other half is urban/developed. No lands of significant ecological value exist in the limited footprint of the project and its run-of-river operations minimize disturbance to the shoreline and watershed resources at either development.

Threatened or endangered species potentially present in the project vicinity include the Northern long-eared bat. A primary concern for the species is habitat disruption via tree/vegetation maintenance. Regular maintenance at the Quinebaug development includes vegetation removal; mainly lawn mowing and brush upkeep. The Five Mile development is surrounded by dense residential and urban land use. Through consultation with the Connecticut State Natural Diversity Database, no critical habitats for the bats were identified in the project area and it is further unlikely that the species is present due to the projects small area and urban location.

Historic structures near the project reach include remains from the Quinebaug Mill – Quebec Square Historic District, listed on the National Register of Historic Places. Any land-disturbing activities must be preceded by consultation with the State Historic Preservation Office.

There are no formal recreation facilities at the project. Public access is provided free of charge but only where safe. Boat barriers are in place upstream of the dams and informal fishing access is provided at the confluence of the Quinebaug and Five Mile Rivers and in the project impoundments. Public use of any informal recreation areas has historically been limited.

Compliance Status

The Certificate includes the following facility-specific condition:

  • Condition 1: The Facility Owner shall notify LIHI of installation of upstream and/or downstream passage facilities at the Wyre Wynd (Aspinook Pond Dam) Project and provide a schedule for installation of passage facilities at the Quinebaug-Five Mile Pond Project in accordance with the existing FERC license article 402.

2022: No material changes or compliance issues were identified. The project remains in compliance based on the annual review.  The project started FERC relicensing with filing of the PAD on February 28, 2022. For Condition 1, the project reported no change in status. 

2021: There were no reported changes or compliance issues. The project remains in compliance based on the annual review. For Condition 1, the project reported no change in status.

2020: There were no reported changes or compliance issues. The project remains in compliance based on the annual review. For Condition 1, the project reported no change in status.

2019: 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.

December 10, 2019: The decision to certify the Quinebaug – Five Mile Pond project is final. No appeal requests were received during the appeals period that closed December 1, 2019. The project is LIHI #166 with a term from June 21, 2019 – June 20, 2024.

October 31, 2019: The Low Impact Hydropower Institute has preliminarily approved Low Impact Certification for the Quinebaug – Five Mile Pond 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 “Quinebaug – Five Mile Pond Hydroelectric Project” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 329 Massachusetts Ave, Suite 6, 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 December 1, 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 #166) will be June 21, 2019 for a term of five (5) years, which will expire on June 20, 2024.

August 24, 2019: The public comment period has closed, the application remains under review pending receipt of additional information.

June 24,2019: The Low Impact Hydropower Institute has received a complete application for Low Impact Certification of the Quinebaug – Five Mile Pond 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 “Quinebaug – Five Mile Pond Project Comments” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 329 Massachusetts Avenue, Suite 6, Lexington, MA 02420.  Comments must be received on or before 5 pm Eastern time on August 23, 2019 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.


2019 Certification