The Cavendish Hydroelectric Project is located in the town of Cavendish, Windsor County, Vermont, on the Black River, 20.8 miles upstream of its confluence with the Connecticut River.  The 1,513 acre Proctor-Piper State Forest is located one-half mile southwest of the Project.  Hawks Mountain Wildlife Management Area borders the Project on the northeast.  Okemo Mountain Ski Area is located about 5 miles upstream of the Project.

Project Name Cavendish
LIHI Certificate Number 97
LIHI Effective and Expiration Dates February 6, 2012
February 6, 2017
(extended to March 31, 2018)
Owner Green Mountain Power Corporation
State Vermont
Location Located at river mile 20.8 on the Black River, a tributary of the Connecticut River, in the Town of Cavendish in Windsor County, Vermont.
Installed Capacity 1.4 MW
Average Annual Generation 5,918 MWH (10 year average)
Facility Type Run-of-river
FERC No. 2489

The 10-acre impoundment extends 3,000 feet upstream from the dam, with a normal elevation of 884.13 feet above mean sea level (msl).  The concrete gravity dam is 75 feet high and set into ledge outcroppings on both sides of the river.  The north spillway section is 90 feet long by 25 feet high and is topped with a 6-foot inflatable rubber flashboard installed in 1995.  The south spillway section is 21 feet long by 6 feet high and topped with 2.5-foot flashboards.  There is a concrete intake structure on the north bank of the river, which serves as the north abutment of the dam.  The intake is equipped with manually operated headgates and an inclined trashrack.

The steel penstock is 6 feet in diameter and 1,250 feet long.  A penstock manifold is located adjacent to the powerhouse and splits flow to the three horizontal shaft Francis turbine generators, each with a capacity of 480 kW, for a total of 1,440 kW of installed capacity.   Appropriate generator leads and transformers connect the Project to the interconnected transmission and distribution system at the substation located adjacent to the access road and directly across from the powerhouse entrance.  Maintenance buildings are co-located with the powerhouse and substation.

The Project is operated as a run-of-river facility.  When the project is not operating, all flows are spilled from the dam.  The 1,570-foot long bypass reach includes Cavendish Gorge, a series of waterfalls and cascades that flow over boulders and between steep cliffs, with numerous pools and glacial potholes formed in the channel.



Cavendish dam

Cavendish Dam

Cavendish gorge 1

Cavendish Gorge

Certification History

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

May 22, 2017: LIHI has received an application for a new term of Low Impact Certification for the Cavendish Hydroelectric project.  LIHI is seeking public comment on this application.  Specifically, we are interested in knowing whether you think the Cavendish project meets the LIHI Low Impact Certification Criteria, as revised in the 2nd Edition Handbook released in March 2016.  Please review the program and criteria in LIHI’s revised Handbook and then review the Project’s 2016 application materials posted on the project page.

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 “Cavendish Lower Project Comments” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, PO Box 194, Harrington Park, New Jersey 07640.  Comments must be received at the Institute on or before 5 pm Eastern time on July 21, 2017 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.

December 16, 2016: The Cavendish 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.

November 29, 2012: The Cavendish 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 application has closed.

February 6, 2012: The Central Vermont Public Service (CVPS) has submitted an application for the certification of the Cavendish Project. Public comment period has opened on the application.

Cavendish gorge potholes 1

Cavendish “Pot holes”


2012 Certification