LIHI Certificate #148 – Waterbury Project, Vermont

The Waterbury Hydroelectric Project (FERC No. 2090) (Project) is located at river mile 2.5 on the Little River in the town of Waterbury, Washington County, Vermont. It is the only hydroelectric plant located on the Little River. The Project’s hydroelectric facilities are owned and operated by Green Mountain Power Corporation (GMP).

The Waterbury reservoir was built by the U.S. Army Corps of Engineers (USACE) for the purpose of flood control in the Winooski River Valley following the flood of 1927. Although the Waterbury Dam and reservoir were built by the USACE in 1938, they are owned by the State of Vermont and operated by GMP for flood control and power generation. Federal oversight of the Waterbury Dam is continuing and significant. Because of federal oversight, the dam and reservoir are not part of the Waterbury Hydroelectric Project works or Project boundary. The Project was issued a new operating license by the Federal Energy Regulatory Commission (FERC or Commission) on February 19, 2016.

The Project works are limited to the powerhouse, penstock, and the transmission lines from the powerhouse to the adjacent substation. The gatehouse is part of the USACE dam structure. Project structures include: a concrete intake structure and broom gate; an 825-foot- long, 10.5-foot-high, 14-foot-wide horseshoe shaped reinforced concrete tunnel; two 205-foot-long, 4.5-foot-diameter penstocks; a 25-foot-long, 6.7-foot-diameter penstock with a new 6.5-foot diameter butterfly valve; a 58-foot-long, 35-foot-wide powerhouse containing a 5.52-megawatt turbine-generator unit with a new turbine runner with a minimum and maximum hydraulic capacity of 49 cubic feet per second (cfs) and 391 cfs; a 12-foot-long, 2.0-foot-diameter penstock drain pipe and valve; a new 60-foot-long, 4.0-foot-diameter bypass penstock with a 4.0-foot-diameter butterfly valve connected to a 2.0- foot-diameter Howell-Bunger valve; a 50-foot-long, 33 kilovolt transmission line from the powerhouse to the substation; and appurtenant facilities.

The license includes three Stages of operation. Stage I covered operations before recent Project modifications were made. Stage II operations began in Spring 2018 when the modifications were complete. Stage III operations will commence when VT and the USACE complete improvements to the Tainter gates and spillway. At that time the Project will operate as a year-round run-of-river project.

Under the former Stage I procedures, the reservoir was drawn down seasonally beginning no earlier than January 1 to an elevation no lower than 550 feet. Spring refill commences no later than March 15 with reservoir levels rising or stable at all times until the normal operating level (NOL) of 589.5 feet is reached by no later than May 15. During the current Stage II operations, the reservoir level is maintained at the NOL except during high inflows. The two-foot cycling around the NOL allowed during Stage I from the end of the spring refill period (no later than May 15) until the seasonal drawdown commences (no earlier than January 1 no longer applies. The timing and maximum drawdown of the seasonal drawdown/refill is the same as in Stage I. Under the future Stage III operations, seasonal drawdowns will no longer apply, and the year-round target elevation of the reservoir will be NOL (589.5 feet). When inflow to the reservoir exceeds Project capacity, the Project will operate at its maximum capacity (maximum turbine capacity plus maximum bypass capacity) and the elevation of the reservoir will exceed 589.5 feet. On these occasions, GMP will operate the Project at its maximum capacity until inflows recede and the reservoir returns to elevation 589.5 feet.

Project Name Waterbury
LIHI Certificate No. 148
LIHI Certificate Term November 16, 2018 - November 15, 2023 (option to extend to November 15, 2026)
Owner Green Mountain Power Corp.
State Vermont
Location river mile 2.5 on the Little River
Installed Capacity 4.102 MW
Average Annual Generation 17,562 MWh (2016)
Facility Type Run of river
FERC No. P-2090 issued 2016, expires 2056

Certification History

March 11, 2019: The decision to certify the Waterbury Hydroelectric Project is final. No appeals were received during the appeal period which closed on March 8, 2019. The certification term for the Project is from November 16, 2018 through November 15, 2023 with an opportunity to extend the term to November 15, 2026. The certificate includes the following conditions:

  • Partially Satisfied 2019. Condition 1: Upon completion of the current water year under Stage II operations (Oct. 1, 2018 – Sep. 30, 2019), the facility Owner shall provide a report to VANR and LIHI that documents run of river compliance, adjustments made over the monitoring period, and recommendations for any additional refinement and/or monitoring needed to ensure compliance. The report shall be provided by December 31, 2019. Thereafter, the facility Owner shall provide annual status summaries of run-of-river operations in annual compliance submittals to LIHI.
  • Satisfied 2019. Condition 2: The Facility Owner shall provide updates in their annual compliance submittals to LIHI summarizing progress made toward completion of recreation enhancements until all required improvements have been made and approved by FERC.
  • Condition 3 (optional): If at any time prior to six months before the expiration of the Certification term the Facility Owner provides evidence that the Project meets the Plus standard for water quality based on continued implementation of the Tailrace Dissolved Oxygen Enhancement and Monitoring Plan (TDOEMP); that results indicate that TDOEMP implementation measures are appropriate; and that VDEC concurs with continued implementation of the TDOEMP; LIHI will review that information and determine whether or not to award the Plus and extend the Certificate term for three additional years.

February 6, 2019: On February 5, 2019, the Low Impact Hydropower Institute (LIHI) preliminarily approved Low Impact Certification for the Waterbury 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 “Waterbury 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 March 8, 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 #148) will be November 16, 2018 through November 15, 2023 with an option to extend the term three years to November 15, 2026.

November 20, 2018: The Low Impact Hydropower Institute has received a complete application for Low Impact Certification of the Waterbury Hydroelectric Project (FERC No. 2090). The Project is located on the Little River in the in the town of Waterbury, Washington County, 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 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 “Waterbury 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 on or before 5 pm Eastern time on January 19, 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.