LIHI Certificate #162 – Hooksett Project, New Hampshire

The Hooksett Project is one of three developments along 21 miles of the Merrimack River, together comprising the Merrimack River Project (FERC No. 1893). Located 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 project first came online in 1927 as a means to supply energy to the area.

The project includes: a dam, two spillway sections, canal, powerhouse, tailrace, bypassed reach, and single turbine.

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 is 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 1.6 MW. The development has an approximate 110-foot long tailrace and a bypassed reach approximately 430 feet long.

The Hooksett impoundment extends upstream approximately 5.5 miles and has a surface area of 350 acres. The project is operated in a run-of-river mode with a minimum flow of 64 cfs provided at all times into the bypassed reach for the protection of aquatic life. Installed pressure gauges allow for spill of any flow beyond generation capacity. This flow regime is based on a habitat-based flow demonstration study conducted in collaboration with USFWS, New Hampshire Department of Fish and Game, and New Hampshire Department of Environmental Services.

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

The Merrimack River in the vicinity of the project is designated a Class B water, best suited for primary contact recreation and aquatic habitat. However, the waters are also listed as impaired for dissolved oxygen (DO), pH, and aluminum with the associated point source unknown. It is unlikely that project operations contribute to DO impairment due to its run-of-river operations. pH is naturally low in many New Hampshire waters and is not likely to be caused by the project.

Migratory fish species within the project reach include American shad, alewife, blueback herring, rainbow smelt, Atlantic salmon, and American eel. Upstream passage facilities are currently under development with construction expected to be completed in November 2021. A nature-like rockway at the spillway will be located off the tailrace island with natural steps that remain wetted. Coupled with a minimal dam height, American eel should be able to pass along with anadromous fish species. A downstream fish bypass gate is operated between April 1 and July 15 and between September 15 and November 15.

The project lands consist of roughly 50 acres. Shoreline around the project area is developed primarily by residential, commercial, and industrial areas. Virtually no buffer between project waters and adjacent lands exists. The project operates under a Shoreline Management Plan which includes provisions for bald eagle monitoring. Though no longer required, the project maintains case-by-case review of proposed shoreline uses and does not allow for any uses that may affect bald eagles or their natural habitat. Field surveys are conducted roughly every six years to examine any unpermitted uses within the Shoreline Management area.

Threatened or endangered species potentially present in the project vicinity include the Northern long-eared bat and small whorled pogonia. Due to the development of the area, it is unlikely that the Northern long-eared bat would find suitable habitat in the project vicinity. However, the area could be used for feeding and transit. The small whorled pogonia prefers upland sites in mixed deciduous/mixed deciduous and coniferous forests in second or third growth successional stages. Due to the lake/riverine characterization of the project area, it is very unlikely to be present. Consultation with the New Hampshire Natural Heritage Bureau has confirmed that run-of-river operations mitigate any potential impacts to listed species.

Within the project vicinity, there are seven historic archaeological sites, 11 shoreline locations considered sensitive for intact prehistoric archaeological resources, and 14 locations with more than low potential for intact historic archaeological resources. Facilities at the project including the powerhouse, dam, spillway, and Tainter gate structure are eligible for listing on the National Register of Historic Places. These sites are monitored by the project owner who must consult with the State Historic Preservation Office prior to conducting any ground-disturbing activities.

The only formal resource in the project reach is a canoe portage takeout at the dam. Other resources exist in the Merrimack River Project at Garvin Falls and Amoskeag developments. The Merrimack River Projects operate under a Recreation Management Plan that was developed in consultation with state agencies and recreational stakeholders. Public access is provided free of charge.


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 comments@lowimpacthydro.org 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 comments@lowimpacthydro.org 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.