Arnold Falls dam

Arnold Falls Dam

The Arnold Falls Project is located approximately 5.5 miles downstream of Pierce Mills, at river mile 9.7. It was built in 1928 by the Twin State Gas & Electric Company following the 1927 flood which did extensive damage to a “small and old station” on the north bank of the river. The falls bear the surname of Dr. Jonathan Arnold, an early settler and entrepreneur who constructed the first sawmill there in 1787 and a gristmill the following year. The Project impounds a 7.2-acre reservoir that extends about 2,200 feet upstream with a water surface elevation of 574.7 feet msl and about 10.8 acre-feet of usable storage. In 2009 the existing timber crib dams were abandoned in place and replaced with a reinforced concrete gravity dam immediately downstream of the timber crib dams.

Project Name Arnold Falls
LIHI Certificate Number 93
LIHI Effective and
Expiration Dates
February 6, 2012
February 6, 2017
(extended to September  30, 2018)
Owner Green Mountain Power Corporation
State Vermont
Location Located at river mile 9.7 on the Passumpsic River, a tributary of the Connecticut River, approximately 5.5 miles downstream of the Pierce Mills project.
Installed Capacity 350 kW
Average Annual Generation 1,484 MWh
Facility Type Run-of-river
FERC No. 2399

The North Dam is 180 feet long by 18 feet high, with a dam crest elevation of 573.00 feet msl.  It is topped with 18-inch hinged steel flashboards. The South Dam is 65 feet long by 15 feet high, with a crest elevation of 572.0 feet msl, topped with an inflatable flashboard system. The intake is 20 feet wide with trashracks and a manually operated bulkhead gate.

The powerhouse contains one vertical shaft turbine rated at 335 kW and a generator rated at 350 kW. A substation is located adjacent to the intake. The downstream fish passage facility is located in the sluiceway of the spillway adjacent to the intake.  The bypassed reach is about 300 feet long. The project has a hydraulic range of 150 to 262 cfs and an average annual generation of about 1,274 MWh.

Arnold Falls powerhouse

Arnold Falls Powerhouse

Certification History

July 12, 2018: The Low Impact Hydropower Institute (LIHI) preliminarily approved the Arnold Falls Hydroelectric Project for a new 5-year term of Low Impact Certification.

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 “Arnold Falls 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 August 11, 2018.  The full application and reviewer’s report are available below.

If no appeal requests are received and the decision becomes final, the new term for the Arnold Falls Project will be February 6, 2017 through February 5, 2022.

June 11, 2018: The Arnold Falls certification term has been extended again to September 30, 2018.

April 3, 2018: The Arnold Falls y certification term has been extended again to June 30, 2018.

November 28, 2017: The Arnold Falls  certification term has been extended to March 31, 2018.

December 30, 2016: The Low Impact Hydropower Institute has received a complete application for a new term of Low Impact Certification for the Arnold Falls Hydroelectric project. The application materials can be found in the Files section below.

LIHI is seeking public comment on this application.  Specifically, we are interested in knowing whether you think the Arnold Falls 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 “Arnold Falls 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 March 4, 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 Arnold Falls Hydroelectric project has been granted an extension of the current certificate term. The new expiration date is May 6, 2017. See extension letter for explanation below.

September 9, 2012: The Arnold Falls 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 Corporation has submitted an application for the certification of the Arnold Falls project. Public comment period on application has opened.


2017 Re-certification

2012 Certification