LIHI Certificate #162 – Hooksett Project, New Hampshire

The Hooksett Development is one of three developments that comprise the Merrimack River Project (FERC No. 1893), located along 21 miles of the Merrimack River. The development is in the towns of Hooksett and Bow, Merrimack County, New Hampshire. The development is approximately 8 miles upstream of the Amoskeag development and approximately 5.6 miles downstream of the Garvin Falls development. The Merrimack River Project is owned by HSE Hydro NH, LLC and operated by Central Rivers Power NH, LLC.

The Hooksett development’s impoundment extends upstream approximately 5.5 miles and has a surface area of 350 acres.  The dam has two spillway sections. A stone masonry section, approximately 340 feet long, extends from the west bank of the river. The second section is approximately 250 feet long and made of concrete. This section runs longitudinally up and down the river near the east bank of the river and forms a canal that extends to the powerhouse; each section topped with 2-foot- high wooden flashboards. There is a 13-foot-by 20-foot steel Tainter wastegate located between the second spillway section and the powerhouse.  A 200-foot-long power canal is located at the east of the dam.  The powerhouse contains a single vertical propeller turbine generator with an installed capacity of 1,600 KW. The development has an approximate110-foot long tailrace and a bypassed reach approximately 430 feet long.   Hooksett is operated in run-of-river mode with a minimum flow of 64 cfs at all times into the bypassed reach for the protection of aquatic life.

The U.S. Fish and Wildlife Service fishway prescription requires the installation of upstream passage facilities for anadromous fish at the Hooksett dam, to be operational within three years after passage of either 9,500 or more shad or 22,500 or more river herring in any given year at the Amoskeag development. The trigger number for river herring was reached during the 2016 migration season. As such, the former owner, Eversource, initiated consultation with state and federal agencies to begin preliminary design work and HSE continues to consult with the agencies to determine the most feasible design in terms of size, location, target species, project operations, cost, and constructability. The existing downstream fish passage is a gate between the Tainter gate and the powerhouse.

Project Name Hooksett
LIHI Certificate No. 162
LIHI Certificate Term May 17, 2019 - May 16, 2024
Owner Central Rivers Power NH, LLC
State New Hampshire
Location River Mile 81.1 on the Merrimack River
Installed Capacity 1.6 MW
Average Annual Generation 8,020 MWh
Facility Type Run of river
FERC No. P-1893 issued 2007, expires 2047

Certification History

September 10, 2019: The decision to certify the Hooksett Hydroelectric Project is final. No appeals were received during the appeal period which closed on September 7, 2019. The certification term for the Project is from May 17, 2019 through May 16, 2024. The Certification includes one condition:

  • Condition 1: The Facility Owner shall provide status updates to LIHI in annual compliance submittals on: a) the upstream fish passage consultation and construction schedule; and b) on downstream eel passage effectiveness studies. The annual status update shall include all agency consultation records and concurrence on the final fish passage measures and effectiveness. LIHI reserves the right to modify certification based on passage effectiveness results.

August 8, 2019:  The Low Impact Hydropower Institute has preliminarily approved Low Impact Certification for the Hooksett 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 “Hooksett Hydroelectric Project” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 329 Massachusetts Ave, Suite 6, 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 September 7, 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 #162) will be May 17, 2019 for a term of five (5) years, which will expire on May 16, 2024.

May 20, 2019: The Low Impact Hydropower Institute has received a complete application for Low Impact Certification of the Hooksett Hydroelectric Project.  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 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 “Hooksett Project Comments” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 329 Massachusetts Avenue, Suite 6, Lexington, MA 02420.  Comments must be received on or before 5 pm Eastern time on July 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.