Penacook Upper Falls

The project is located on the lower Contoocook River in Merrimack County in the southeastern New Hampshire Village of Penacook. The Contoocook River enters the Merrimack River upstream of the fifth mainstream dam. The Village of Penacook is made up of a small part of the Town of Boscawen and the northern end of the City of Concord. The project is located on the extreme northern end of Concord, with a section of the tailrace crossing into Boscawen (lat. 43°16’50”N, long. 71°36’00”W).

Project Name Penacook Upper
LIHI Certificate Number 52
LIHI Effective and
Expiration Dates
September 25, 2014
September 25, 2019
Owner Briar Hydro Associates
State New Hampshire
Location Located on the Contoocook River in the Village of Penacook, New Hampshire.
Installed Capacity 2,800 kW
Average Annual Generation 14.5 GWh
Facility Type Run-of-river
FERC No. 6689

The facility is a 21‐foot high, 187‐foot long structure with a spillway built on the remains of an existing dam. It consists of a timber stoplog dam, one generating unit (2,800 kW), and appurtenant facilities. The dam is at an elevation of 306 feet MSL and it creates a pool with a surface area of approximately 11.4 acres. The facility also includes:

  • 16 gates in the spillway, 6 operable timbergates,9.5 feet wide and 15.5 feet high;
  • 8 fixed timber stopgate logs, and two operable (ice) gates, 12 feet wide and 3.5 feet high;
  • a gross reservoir volume of 70 acre feet and a net storage capacity of 0.23 billion gallons;
  • a powerhouse at the east side of the dam with one generating unit having an installed capacity of 2,800 kW;
  • a 35.0 foot long, 4.16 kV generator lead;
  • a 4.16/34.5 kV 3.6 MVA three‐phase transformer;
  • a 50‐foot long 34.5 kV overhead transmission line; and
  • a tailrace, 47 feet wide and 350 feet long.

A concrete powerhouse, 81 feet long and 44 feet wide, is located on the east river bank. The powerhouse contains one horizontal shaft tube turbine with a capacity of 2,800 kW. The riverbanks upstream and downstream of the powerhouse are contained by concrete retaining walls to bedrock. A 47‐foot wide (average) tailrace exists at the draft tube exit of the powerhouse and extends approximately 350 downstream to provide downstream fish passage. A 15‐foot long forebay with a 58‐foot (average) width begins and the powerhouse and extends upstream. From the southwest corner of the powerhouse, a concrete gated spillway extends 187 feet across the river. The project is operated as a run‐of‐river facility.

Penacook Hydro Associates (PHA) began construction of the project in 1984 and completed construction in 1986, when the project first generated power. PHA operated the facility until 1993 when FERC authorized the transfer of the project license to Briar. PHA is a general partner of Essex Hydro Associates (Essex); Essex is also a general partner of Briar. The license was transferred in 1993 from PHA to Briar (the project operator) to simplify administration of the project.

The FERC license Article 26 requires the Facility to be operated as a run‐of‐river facility with a continuous minimum flow of 338 cubic feet per second (cfs) or the inflow to the reservoir, whichever is less.

Penacook Upper Falls-resized

Certification History

August 5, 2016: LIHI Executive Director, Michael J. Sale, using authority delegated from the LIHI Governing Board, has certified that the Penacook Upper Hydroelectric Project (FERC No. P-6689) satisfies the LIHI Certification Criteria. A Preliminary Decision was announced on June 17, 2016, and a 30-day appeal period was open through July 17, 2016. No requests for appeal were received. This Certification Decision includes two facility-specific conditions, as follows:

  • Condition 1.  The facility owner shall consult with NHDES to determine the most appropriate and efficient way to report on minimum flows and pond level fluctuations, then, after reaching agreement with NHDES on best methods, complete the subject summary report on or before the end of December 2016. The owner shall provide a copy of this report to LIHI along with all related correspondence.
  • Condition 2.  Within 30 days after LIHI recertification, the facility owner shall complete consultation with the NHDES to finalize the details of an alternative approach for spot testing the current water quality conditions at the facility. The owner shall provide LIHI with all related correspondence pertaining to resolution of this issue and with the water quality data once testing has been completed.  The owner shall complete the water quality testing before the end of December 2016, weather permitting.

The effective certification date for the Penacook Upper Project is September 25, 2014 for a five (5) year term, which will expire on September 25, 2019.

October 30, 2015: The Low Impact Hydropower Institute has received a complete application for a new term of Low Impact Certification for the Penacook Upper Hydroelectric project.  The application materials can be found in the Files section below.

The public comment period for this application closed on December 30, 2015.

September 4, 2015: The Penacook Upper Hydroelectric project has been granted an extension of the current certificate term. The new expiration date is December 31, 2015. See the extension letter in the Files section for explanation below.

April 21, 2010: The Penacook Upper Hydroelectric Project has been certified as low impact for a five year term, effective September 25, 2009 and expiring September 25, 2014.

November 25, 2009: The public comment period has been closed.

September 25, 2009: Briar Hydro Associates has submitted an application for certification of the Penacook Upper Falls Hydroelectric Project. A public comment period will remain open for 60 days.


Files: