LIHI Certificate #95 - Passumpsic Project, Vermont

The Passumpsic River Project is located in northeastern Vermont near St. Johnsbury, in Caledonia County, on the Passumpsic River. It is the second dam on the river and located at river mile 5.5, downstream of several projects including the Gage Project (LIHI #94), Arnold Falls (LIHI #93), and Pierce Mills (LIHI #92). The East Barnet Project (FERC No. 3051) is the first dam on the river. The river is 22.7 miles long and a tributary to the Connecticut River, entering just downstream of Comerford Dam (part of LIHI #39).

The Passumpsic River Project was built in 1905 - 1906 for the St. Johnsbury Electric Company. The powerhouse was completely destroyed in the flood of 1927. Portions of its foundation and those of its associated power canal remain buried on the other side of the existing canal. The plant was rebuilt in 1929 in the location of the Chase leatherboard mill water wheel, which was also destroyed in the flood. The building behind the powerhouse is the remainder of the former leatherboard mill. The project is owned by Green Mountain Power (GMP), the first energy utility certified as a B-Corporation.

The project includes a dam, flashboards, headgate, power canal, powerhouse, intake, spillway, one vertical shaft turbine, bypassed reach, and substation.

The concrete gravity dam consists of two sections: a south section 122-feet-long with a maximum height of 10-feet, topped with 1-foot-high flashboards; and a north section 126-feet-long with a maximum height of 10-feet, topped with 1-foot-high flashboards. The dam is equipped with a 27-foot-wide headgate structure with two gates. The power canal conveys flow to the powerhouse via an integral intake with an inclined trashrack. The canal is 19 to 22-feet-wide and 87-feet-long. There is also a sluice and a 24-foot-long overflow spillway. The powerhouse contains one vertical shaft turbine and generator with an installed capacity of 0.7 MW, as well as appurtenant equipment. A substation is located adjacent to the power canal. The downstream fish passage facility consists of a sluiceway in the spillway adjacent to the canal headworks. The bypassed reach is about 350-feet-long.

Project Name Passumpsic
LIHI Certificate No. 95
LIHI Certificate Term February 6, 2017 - February 5, 2022
Owner Green Mountain Power Corporation
State Vermont
Location Located at river mile 5.5 on the Passumpsic River, a tributary of the Connecticut River, approximately 1.7 miles downstream of the Gage Project.
Installed Capacity 0.7 MW
Average Annual Generation 1,998 MWH
Facility Type Run-of-river
FERC No. P-2400 issued 1994, expires 2034

The project operates in a run-of-river mode and impounds an 18.3-acre reservoir. The project provides an 86-cfs minimum flow into the bypass reach. Portions of this flow are used for aesthetic enhancement and fish passage seasonally. Aesthetic flows are provided from June 1 through October 31 and fish passage flows (9-25 cfs) are provided from April 1 through June 15 and from September 15 through November 15. The flow regime was developed with recommendations from the Vermont Agency of Natural Resources (VANR) and United States Fish and Wildlife Service (USFWS).

Waters within the project reach are designated Class B and impaired for E. coli contamination due to the St. Johnsbury wastewater treatment plant passing combined sewer overflows. VANR has confirmed that the project does not adversely impact water quality and is not the source of river impairments. Class B waters are managed to support aquatic biota, wildlife, and aquatic habitat, public water supply, irrigation, primary contact recreation, and aesthetics.

While the Connecticut River Basin historically hosted naturally occurring Atlantic salmon runs, the species was extirpated from the river system due to the construction of dams. These downstream dams create a barrier to upstream passage at the project. Resident species of the Passumpsic River include brown trout, brook trout, and rainbow trout. Downstream passage is facilitated via a surface bypass flume and a 24-inch-diameter transport pipe with a 9-25 cfs passage flow. Trashracks with 1-inch spacing mitigate the potential for entrainment. The project owner consulted with USFWS and VANR to develop this passage facility.

The project lands consist of 34 acres. The area surrounding the impoundment and project lands are primarily rural residential housing and farmland. No lands of significant ecological value exist in the area and run-of-river operations mitigate the potential for erosion of the shoreline.

Threatened and endangered species potentially within project vicinity include the Northern Long-eared Bat and Garber's sedge. The primary concern for the listed species is the disruption of critical habitat. Consultation with the VANR concluded that project operations and the construction of the downstream passage facility would not have any negative impact on the listed species.

Cultural resources in the project area include the project infrastructure which is eligible for listing on the National Register of Historic Places. The project owner submits annual reports to the Vermont Division for Historic Preservation on any activities pertinent to the stewardship of the project’s cultural resources.

Recreational resources at the project include a canoe portage and picnic area. The project owner voluntarily revised the Passumpsic River Canoeing and Recreation Guide and provides guided facility tours. Public access is provided free of charge.

Certification History

October 10, 2018: The decision to recertify the Passumpsic Hydroelectric Project is final. No appeals were received during the appeal period which closed on October 6, 2018. The new certification term for the Project is from February 6, 2017 through February 5, 2022.

September 6, 2018: On September 4, 2018, the Low Impact Hydropower Institute (LIHI) preliminarily approved the Passumpsic Hydroelectric Project for a new 5-year term of Low Impact Certification, with the following conditions:

  • Condition 1: The Owner shall provide LIHI with evidence that FERC has approved the Revised Flow Management Plan (filed by GMP on April 25th, 2018) within 60 days from the date of issuance of that approval.
  • Condition 2: The Owner will provide LIHI with evidence that FERC has approved the Downstream Fish Passage and Operations and Maintenance Plan (filed by GMP on April 25th, 2018) within 60 days from the date of issuance of that approval.  If FERC issues new terms and conditions, the LIHI Certification is subject to amendment to incorporate such terms and conditions.
  • Satisfied in 2018. Condition 3: The Owner shall provide a LIHI with a copy of the final report to FERC demonstrating the completion of the portage pathway improvements within 60 days of filing that report with FERC.

This decision is preliminary pending the 30-day appeal window. Only those who commented in 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 projects do not meet the LIHI criteria. Appeal requests can be submitted by email to with “Passumpsic 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 and 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 October 6, 2018.  The full application and reviewers report are available HERE.

If no appeal requests are received and the decision becomes final, the new term for certification will be February 6, 2017 - February 5, 2022.

June 12, 2018:The Low Impact Hydropower Institute has received a complete application for a new term of Low Impact Certification for the Passumpsic Hydroelectric Project (LIHI # 95). The Project is located on the Passumpsic River in St. Johnsbury, Vermont.

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 2018 application materials posted 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 “Passumpsic 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 August 11, 2018 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.

June 11, 2018: The Passumpsic Hydroelectric project has been granted another extension of the current certificate term. The new expiration date is November 30, 2018.

November 28, 2017: The Passumpsic Hydroelectric project has been granted another extension of the current certificate term. The new expiration date is March 31, 2018.

December 16, 2016: The Passumpsic Hydroelectric project has been granted an extension of the current certificate term. The new expiration date is August 6, 2017. See extension letter for explanation below.

September 13, 2012: The Passumpsic Project has been certified as low impact for a five year term, effective February 6, 2012 and expiring February 6, 2017.

April 6, 2012: Public comment period on the application has closed.

February 6, 2012: The Central Vermont Public Service Corporation has submitted an application for the certification of the Passumpsic  Project. Public comment period has been opened.