LIHI Certificate #43 - Deer Island Project, Massachusetts

Project Name Deer Island
LIHI Certificate No. 43
LIHI Certificate Term August 6, 2019 – August 5, 2034
Owner Massachusetts Water Resource Authority
State Massachusetts
Location Located at the Deer Island Wastewater Treatment Plant on Deer Island in Boston Harbor, Boston, Massachusetts.
Installed Capacity 2.2 MW
Average Annual Generation 5,000 MWh
Facility Type conduit
FERC No. P-11412 exempt 1993

The Deer Island Project is located at the Massachusetts Water Resources Authority’s (MWRA) Deer Island Wastewater Treatment Plant. The project is situated in the vicinity of the pumping station at the Wastewater Treatment plant on Deer Island, in Boston Harbor, Boston, MA. The project is a conduit facility and received a conduit exemption from FERC. The hydroelectric facility was also part of a thorough environmental review by state and federal agencies as part of the Deer Island Water Treatment Plant. The Deer Island Treatment Plant discharges, including all discharges through the hydropower plant, received both an EPA NPDES permit and MA Division of Water Pollution Control Water Quality Certification. The project was brought online in 2001 and exclusively provides power to the wastewater treatment facility.

The project process is as follows: once treated wastewater is disinfected, it is discharged into Effluent Channel 1. Flow is then split through two horizontal intake openings at the base of Effluent Channel 1 and transmitted through separate rectangular concrete conduits below the disinfection basin to two corresponding hydro turbines. The two intake openings in Effluent Channel 1 are each approximately 20 feet by 18 feet. The intakes decrease to 11 feet by 11 feet at motorized roller intake gates located immediately upstream of the turbines. The hydropower facilities include two Kaplan units with a total installed capacity of 2 MW. Turbine runner blades and wicket gates are adjusted to meet changing power demands and changes in flow and head. After the turbines, the turbine effluent conduit joins the outfall chute which discharges into the outfall shaft which discharges the effluent into the 9.5-mile outfall tunnel to Massachusetts Bay.

The hydropower facilities’ instrumentation and control system are designed to interface with the wastewater treatment facilities control system. The system allows fully automatic unattended operation. The treatment plant must operate continuously to prevent backups of the sewage collection system. The building that houses the turbines, generators and all associated electrical switchgear equipment is situated directly over Effluent Conduit 1.

The project operates as a conduit facility. Flows are directed from the disinfection basin and are ultimately conveyed into the deeper waters of Boston Harbor. The project does not have any impact on the surrounding environment.

Waters within the project reach meet water quality standards and are unaffected by the project. According to the US Environmental Protection Agency, the NPDES permit associated with the treatment plant imposes rigorous conditions to ensure the protection of Massachusetts and Cape Cod Bays. This includes ambient monitoring, pollution prevention, and best management practice requirements. The permit is also the first of its kind to implement a contingency plan to help ensure that any unexpected problems are dealt with in a timely manner.

The project does not impede fish movement in Boston Harbor as it is located entirely within the treatment plant and fish cannot enter the conduit or its turbines.

The land on Deer Island is highly developed and resistant to erosion. The project has no direct access to or control of the associated lands. The island was first developed for wastewater treatment in the late 1800s. The current treatment plant began operation in 1995.

There are no critical habitats associated with threatened or endangered species potentially present in the project vicinity. The project does not impact any potential species as it is located in the treatment plant. The discharge of the project is periodically tested for toxicity and its potential effects on sensitive marine organisms. Forty-three monitoring stations collect data on nutrients, heavy metals, algae blooms, and more.

The project is located in the vicinity of the New Resthaven Cemetery and Piggery Point, both historic burial grounds. Mitigation efforts to ensure preservation of the sites were approved by FERC in 1994. Additionally, Deer Island has been used for sewage disposal since the 1800s and the original steam pump station, built from 1894 to 1899, is eligible for listing on the National Register of Historic Places. The steam pump was restored by MWRA and is displayed at the treatment facility.

No public access is allowed at the project as the wastewater treatment plant restricts access. Deer Island houses several public walkways surrounding the facility for walking/jogging/bicycling as well as picnic areas, and fishing opportunities. Deer Island is a part of the Boston Harbor Islands National and State Park and provides recreational access to the public.

Compliance Status

There are no facility-specific conditions in the current Certificate

2023: No material changes or compliance issues were identified. The project remains in compliance based on the annual review.

2022: No material changes or compliance issues were identified. The project remains in compliance based on the annual review.

2021: There were no reported changes or compliance issues. The project remains in compliance based on the annual review.

2020: There were no reported changes or compliance issues. The project remains in compliance based on the annual review.

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.

February 10, 2020: The decision to recertify the Deer Island Project became final after the close of the appeals period on February 6, 2020 with no appeals filed.  The Certification term is from August 6, 2019 – August 5, 2029.

January 7, 2020: The Low Impact Hydropower Institute has preliminarily approved Low Impact Recertification for the Deer Island Hydroelectric Project, LIHI #43. 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 “Deer Island 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 February 6, 2020.  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 will be from August 6, 2019 to August 5, 2029.

October 8, 2019: The Low Impact Hydropower Institute has received a complete application for Low Impact Recertification of the Deer Island 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 “Deer Island 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 December 7, 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.

November 19, 2014 – Executive Director Michael J. Sale, using authority delegated from the LIHI Governing Board, has determined that the Deer Island Hydroelectric Project (FERC No. 11412) continues to meet the LIHI Certification Criteria.  The effective date of the certificate is August 6, 2014, and the certificate will expire on August 6, 2019.

June 4, 2014: The Low Impact Hydropower Institute received an application for a second term of certification of the Deer Island Hydropower Project. The application materials can be found in the “Files” section below.

October 22, 2009: The Deer Island Hydroelectric Project has been certified as low impact for a five year term, effective August 6, 2009 and expiring August 6, 2014.

August 6, 2009: The Massachusetts Water Resource Authority has submitted an application for certification of the Deer Island Hydroelectric Project. A public comment period will remain open until October 6, 2009.

Certification Files

2019 Recertification

2014 Recertification

2009 Certification

Key Documents