LIHI Certificate #39 - Fifteen Mile Falls Project, New Hampshire and Vermont


Project Name  Fifteen Mile Falls
LIHI Certificate No. 39
LIHI Certificate Term December 14, 2021- December 13, 2034
Owner Great River Hydro, LLC
State New Hampshire, Vermont
Location Dams are located between river mile 268.6 and 83.5 on the Connecticut River in Grafton County, New Hampshire and Caledonia County, Vermont.
Installed Capacity 338 MW
Average Annual Generation 690,558 MWh
Facility Type Store-and-release
FERC No. P-2077 issued in 2002, expires 03/31/2042

The Fifteen-Mile Falls Project is located on the Connecticut River in Grafton County, New Hampshire and Caledonia County, Vermont. It is the largest conventional hydro project in New England and is comprised of three developments – Moore, Comerford, and McIndoes. Comerford and McIndoes were constructed in the early 1930s, Moore was added later in 1956.

In August 1997, a dozen organizations signed a settlement agreement intended to address a number of objectives, including water quality improvements, habitat enhancement for terrestrial and aquatic biota, wetlands protection, cultural resource preservation, and more. The signatories to the Settlement Agreement (SA) included New Hampshire Fish and Game, New Hampshire Department of Environmental Services, Vermont Agency of Natural Resources, United States Fish and Wildlife Service, United States Environmental Protection Agency, National Park Service, Appalachian Mountain Club, Connecticut River Joint Commissions, Connecticut River Watershed Council (now Connecticut River Conservancy), New Hampshire Rivers Council, North Country Council, Northeastern Vermont Development Association, and New Hampshire Council of Trout Unlimited.

The project is located just upstream of the Dodge Falls Project (LIHI #42) and includes, from upstream to downstream:

  • Moore development which impounds an 11-mile-long reservoir with a surface area of 3,490 acres. The dam is an earth and concrete gravity structure with an overall length of 2,920 feet and a height of 178 feet. It has a 373-foot-long concrete spillway with a 15-foot-wide by 20-foot-high sluice gate, four 50-foot bays of 17-foot-high stanchions, and three bays of 36-foot-wide by 30-foot-high Tainter gates. Four steel penstocks, each 296 feet long, convey flows to the integral powerhouse with four Francis type turbine-generator units with a combined capacity of about 160 MW.
  • The Comerford development impounds an 8-mile-long reservoir with a surface area of 1,093 acres. The earth and concrete gravity dam has an overall length of 2,253 feet and a height of 170 feet. It has an 850-foot-long concrete spillway with six 7-foot-wide by 9-foot-high sluice gates, four bays of 8-foot-high flashboards and seven 10-foot-high stanchion bays. Four steel penstocks, each 150 feet long, convey flows to the integral powerhouse with four Francis type turbine-generator units having a combined capacity of 168 MW.
  • The McIndoes development impounds a 5-mile-long reservoir with a surface area of 543 acres. The concrete gravity dam has an overall length of 730 feet and a height of 25 feet. It has a 520-foot-long concrete spillway with a 12-foot-wide by 13-foot-high skimmer gate, three 24-foot-wide by 25-foot-high Tainter gates, a 300-foot-long spillway flashboard section with 6-foot flashboards, and two 50-foot-wide by 18-foot-high stanchion bays. The integral powerhouse has four Kaplan type turbine-generator units with a combined capacity of 10.5 MW. McIndoes regulates flow from Comerford.

Moore and Comerford have seasonal storage and operate in store-and-release mode while McIndoes serves as a regulating dam to smooth flows from the other two plants. Reservoir fluctuation limits vary by development but during spawning season (May 21-June 30), the developments limit fluctuations to 2 feet to enhance spawning conditions. The developments also provide minimum flow releases that vary seasonally. Moore provides 320 cfs into the tailrace year-round. Comerford provides releases into the tailrace of 818 cfs from June 1 to September 30; 1,145 cfs from October 1 to March 31; and 1,635 cfs from April 1 to May 31. McIndoes provides 1,105 cfs into the tailrace from June 1 to September 30; 2,210 cfs from October 1 to March 31; and 4,420 cfs from April 1 to May 31 to support spring fish spawning and incubation. This flow regime was developed in collaboration with the signatories to the SA based on the results of habitat and flow studies.

The Connecticut River forms the boundary between New Hampshire and Vermont. Thus, the two states agreed on a coordinated approach concerning water quality and issued a single water quality certificate for the project that addresses the interests of both states. The waters in the project reaches are all listed for mercury and pH impairment. Mercury impairment is likely caused by atmospheric deposition from out-of-state sources. The project conducts water quality monitoring of mercury in fish tissue at five-year intervals. State fish consumption advisories are posted based on the monitoring results.

Migratory species in the Connecticut River with historic reach to the Project area include Atlantic salmon and American eel. Upstream fish passage is not currently provided at the project. A triggering provision was included in the SA noting that the presence of 20 migrating adult salmon at the downstream Dodge Falls Dam (LIHI #42) for two consecutive years would require upstream passage for Atlantic salmon, but this provision has not yet been triggered.  An American eel passage plan is ready to be implemented for upstream and downstream passage, if deemed necessary by resource agencies. Downstream passage is no longer provided for Atlantic salmon smolts since the Connecticut River salmon restoration program ended in 2013.

The project lands consist of 6,918 acres of open land around the project developments which has been protected in perpetuity under the terms of 2 separate conservation agreements. Additionally, the project established the Upper Connecticut River Mitigation and Enhancement Fund to mitigate the impacts of project operations. Funds are used to finance river and wetland restoration, protection and enhancement, acquisition of conservation easements, and mitigation of tax revenue impacts to nearby communities and have served to conserve over 14,700 acres of property in the Upper Connecticut River watershed. A wildlife and forest management plan has been implemented at the project which provides for protection of the scenic, forestry, and natural resources values of project lands.

PLUS-Standard: The protected project lands encompass 67% of all owned shoreline lands, thus surpassing the 50% buffer zone requirement for the LIHI criterion.

Threatened or endangered species potentially present in the project vicinity include Canada lynx, Northern long-eared bat, bald eagle, cliff swallow, dwarf wedgemussel, and numerous state-listed plants. The project has developed a land management plan, in consultation with US Fish and Wildlife Service (USFWS), which integrates a threatened and endangered species management plan to ensure project operations do not adversely impact listed species. The dedication of several thousand acres to conservation easements contributes to these mitigation efforts and helps to protect bat and bird roosting sites. USFWS noted that project operations do not impact dwarf wedgemussel populations.

Historic properties include each of the development’s dams and powerhouses. Additionally, there are several archaeological sites at the Moore and McIndoes developments. A cultural resources management plan was implemented at the project, based on consultation with the State Historic Preservation Offices (SHPOs), to ensure proper stewardship of these resources.  Cultural resources are evaluated during planning for any alterations to project facilities, and consultation with the appropriate SHPO is initiated if activities could impact those resources. Biennial reports summarize these evaluations and document consultation.

Recreational resources at the project include a variety of fishing access points, picnic/day use areas, swimming areas, canoe portages, and boat ramps at each development.  Minimum reservoir levels for open water recreation (e.g., boating) at Moore and Comerford reservoirs. The McIndoes development has two camping areas and hiking trails. Maps, recreation facility descriptions and flow forecasts can be found HERE. Public access is provided free of charge.

Compliance Status

The Certificate includes the following facility-specific conditions:

Condition satisfied in 2023. Condition 1: The facility Owner shall provide a status update of the Moore Unit #5 installation and initial operation in the first annual compliance submittal to LIHI after the unit becomes operational. The update shall include copies of any required monitoring and agency comments on the monitoring results. The update shall identify any deviations from the expected design or operating conditions approved by FERC. LIHI reserves the right to require additional information and conduct additional review of impacts if changes in design or operation occur that could affect one or more LIHI criteria.

Condition 2: To confirm satisfaction of the Water Quality criterion and until system acceptance, the facility Owner shall provide in annual LIHI compliance submittals, a summary of the Moore DO monitoring results, agency comments on them, and the final agency acceptance of the DO enhancement system effectiveness, or any modifications needed to improve its effectiveness.

Condition 3: To confirm compliance with the Land Management Plan, the facility Owner shall:

This portion satisfied in 2023. a) Within one year of LIHI Certification, review and update the Land Management Plan, as necessary, to incorporate the current New Hampshire and Vermont forestry Best Management Practices and ensure that similar current state requirements for management of invasive species are included. The forestry practices section shall denote that tree removal near potential bat roosting trees should be avoided, if possible, between April 1 and October 31. Confirmation of this review/updating shall be provided to LIHI in the next annual compliance submittal.

b) In annual compliance submittals, provide confirmation that all provisions of the Land Management Plan have been satisfied in the prior year. Any deviations shall be noted, and actions taken to remedy the situation shall be identified and reported.

Condition partially satisfied in 2024, pending SHPO acceptance. Condition 4: To confirm compliance with the Cultural and Historic Resources criterion, the facility Owner shall provide documentation that the cultural resource protection mitigations required by the SHPO related to installation of Moore Unit #5 have been completed and accepted by the SHPO in the first annual LIHI compliance submittal after acceptance has been received.

Condition 5: To confirm compliance with the Recreational Resources criterion, the facility Owner shall,

a) within one year of LIHI Certification:

This portion satisfied in 2023. i) Provide and maintain information on recreation opportunities at the Project on the company website, including but not limited to one or more maps showing the locations and facility amenities as well as additional information such as permissible times of use and both permissible and restricted activities (if appropriate).

ii) Confirm that fish consumption advisory signage is posted at all public access facilities and contains the most updated advisory information provided by NHDES and VDEC, in accordance with license Article 405. Signage shall be reviewed and updated if needed in consultation with the resource agencies after each 5-year mercury monitoring study is complete and confirmation shall be provided to LIHI in the following annual compliance submittal.

This portion satisfied in 2023. iii) Consult with NHDES and VDEC on installation of signage at the reservoirs about proper boat maintenance to avoid the spread of aquatic invasive species and confirm that periodic inspection of the signage has been incorporated into regular recreation area inspections.

b) per the schedules indicated below:

This portion satisfied in 2023. i) Develop and document a process to ensure periodic re-assessments of public access and use of project lands and waters for recreation and a process for ongoing recreation needs coordination with local entities and interested stakeholders for submittal to LIHI in the 2023 annual compliance submittal.

ii) Provide summaries of all recreation related coordination and copies of related communications that occurred during the prior year in annual LIHI compliance submittals.

iii) By December 31, 2024, and again by December 31, 2030, conduct assessments of public access and recreation use in cooperation with Federal, state, local entities and interested stakeholders, and provide a summary of the assessment results, any plans and schedules for proposed enhancements, and copies of all related stakeholder communications to LIHI in the following year’s annual compliance submittal.

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 minimum flow unit in operation with no changes from the approved design thus satisfying the condition.  For Condition 2, the project reported monitoring to be completed in 2024.  For Condition 3a, the project submitted documentation of the updates to the land management plan, thus partially satisfying this portion of the condition.   For Condition 4, the project documented submission of mitigation information to the SHPOs, thus partially satisfying the condition.  For Condition 5a.i, the project reported updating its recreation information (see, thus satisfying this portion of the condition.  For Condition 5a.ii the project reported signage will be installed in 2024.  For Condition 5a.iii the project reported installation of signage, thus satisfying this portion of the condition. For Condition 5b.i, the project demonstrated a process has been implemented thus satisfying this portion of the condition.  For Condition 5b.ii, the project submitted the required information.  For Condition 5b.iii, the project reported no change in status.

2022: No material changes or compliance issues were identified. The project remains in compliance based on the annual review.  For Conditions 1, 2, 3, and 5 the project reported no change in status. For Condition 4, the project reported flagging a sensitive area to avoid impacts to cultural resources during construction activities.

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

Certification History

August 30, 2022: The Low Impact Hydropower Institute has issued a final decision on the recertification of the Fifteen Mile Falls Project.  The 30-day appeal window closed on August 27, 2022 and no appeals were filed.  Therefore, the decision to recertify the project is now final.  The new term is December 14, 2021 through December 13, 2034 in accordance with the term extension that became effective January 1, 2022 in Revision 2.05 of the LIHI 2nd Edition Certification Handbook.

July 28, 2022: The Low Impact Hydropower Institute (LIHI) has preliminarily approved the Fifteen Mile Falls Project for a new 13-year term of Low Impact Certification. The complete application and reviewer report can be found below. 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 “Fifteen Mile Falls 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 27, 2022. If no appeal requests are received and the decision becomes final, the Certification term for the Project will be December 14, 2021 through December 13, 2034.

January 21, 2022: The Low Impact Hydropower Institute (LIHI) has received a complete recertification application from Great River Hydro for the Fifteen Mile Falls Project. The complete application can be found below. LIHI is seeking comment on this application. 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 LIHI by e-mail at with “Fifteen Mile Falls Project Comments” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 1167 Massachusetts Avenue, Office 407, Arlington, MA 02476. Comments must be received at the Institute on or before 5 pm Eastern time on March 22, 2022 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.

January 24, 2018: Having reviewed information provided by the applicant as required in Condition 3 (text below), LIHI’s Executive Director has determined that Condition 3 is satisfied and Fifteen Mile Falls has earned an additional three years of Certification term. The Certificate term is therefore December 15, 2013 through December 14, 2021. (The decision letter is posted below under Files.)

May 15, 2016: LIHI has received notice that TransCanada Hydro Northeast Inc. was converted to a limited liability company on April 7, 2017, becoming TransCanada Hydro Northeast LLC.  On April 19, 2017, the name of the company was changed from TransCanada Hydro Northeast LLC to Great River Hydro, LLC.

July 10, 2015: Executive Director Michael J. Sale, using authority delegated from the LIHI Governing Board, has determined that the Fifteen Mile Falls Hydroelectric Project (FERC No. P-2077) continues to satisfy the LIHI Certification Criteria. The effective certification date for the Fifteen Mile Falls Project is December 15, 2013 for a five (5) year term, which will expire on December 15, 2018, with the following conditions:

  • Condition satisfied in 2016. Condition 1: Pertaining to the trap and truck operation for downstream passage of Atlantic salmon smolts stocked upstream of the Moore Dam, the facility owner shall remain in full compliance with its FERC license and the associated Settlement Agreement (SA) and Water Quality Certificate. If the licensee requests to amend the FERC license or the WQC, or reopen the SA, with regard to use of this operation, the facility owner shall notify LIHI within seven days, including a description of the proposed changes and schedules for pursuing them. LIHI shall also be provided a copy of any amendments, along with resource agency comments, to confirm continued compliance with LIHI’s criterion.
  • Condition waived with 2021 recertification. Condition 2: As part of the required annual Compliance Statement to LIHI, the facility owner shall identify any violations of FERC operating requirements and will include copies of all agency and FERC notifications and reports of deviations of said operating requirements that have occurred in the previous year. This report shall be submitted by March 31 for the previous year’s events. This report shall reference and include copies of all notifications made to the FERC during the previous year. Unless otherwise included in the FERC notifications themselves, the report to LIHI shall describe for each instance:
    1. The cause of the event/deviation;
    2. The date, duration and magnitude of the deviation;
    3. Confirmation that the required 24-hour notices have been made to NHDES and VTDEC of such events (list the date of and to whom all notifications were sent);
    4. Ways to minimize future repeat occurrences to the extent possible by the Licensee;
    5. Any proposed mitigation measures and a schedule by which such measures will be implemented; and
    6. Status or confirmation that the previously developed mitigation measures (for the previous year) have been implemented according to the proposed schedule.

    The owner shall maintain a proactive approach to reducing the frequency and severity of such deviations to the extent reasonably possible. LIHI shall be informed of the capital improvement projects that are underway and planned for the future to minimize the occurrence of deviations or plant outages. The annual compliance report to LIHI will be used as confirmation that the facility owner is conducting the necessary actions to minimize such events and ensure compliance with LIHI’s flow and water quality criteria.

  • Condition satisfied in 2018, extended term granted. Condition 3: The facility owner shall provide LIHI with a description of the current status and use of funds from the Mitigation and Enhancement Fund that was part of the Settlement Agreement for the most recent FERC licensing.  In particular, this description shall identify the lands and waters that are benefiting from the funds, the current fund balance, and continuing payment schedule, and be sufficient to determine if these funds are achieving the ecological and recreational equivalent of land protection of the buffer zone referred to in Question D.1.  This information will be used by LIHI staff to determine if the Fifteen Mile Falls certification qualifies for three additional years in its term.  The facility owner may or may not take advantage of this opportunity to request an extended term of their new certificate; if they do not provide this additional information, it will not affect the new five-year term.

January 27, 2014: The Low Impact Hydropower Institute has received an application from TransCanada for a second term of certification of the Vernon Station Hydroelectric Project. The 2013 application was received on December 5th, but due to administrative backlog, the certificate has been granted a three month extension beyond the date of December 15th. The application materials can be found in the “Files” section below.

June 25, 2009: The 15-Mile Falls Hydroelectric Project has been certified as low impact for a five year term, effective December 15, 2008 and expiring December 15, 2013.

Certification Files

2021-2022 Recertification

2013 Recertification

2008 Certification

Key Documents