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The dam at this site has been in use since the 1790’s, and was used as a reference marker in laying out the towns. The location was probably chosen due to availability of a rock out crop in the river bed, allowing a solid anchorage for a dam.

Project Name Ice House
LIHI Certificate Number 44
LIHI Effective and
Expiration Dates
August 6, 2014
August 6, 2019
Owner Ice House Partners
State Massachusetts
Location Located on the Nashua River in Ayer, Massachusetts, at the intersection of the towns of Ayer, Harvard, and Shirley.
Installed Capacity 0.280 MW
Average Annual Generation 1,014 MWh (past 12 months)
Facility Type Run-of-river
FERC No. 12769

The Ice House Project uses the existing 190-foot-long, 12-foot-high Ice House dam and spillway topped with existing 24-inch-high flashboards that impound a 137-acre reservoir. The project ha a headgate structure, equipped with four 8-foot-high, 10-foot-wide gates, leading to an existing 50-foot-wide, 109-footlong power canal. The restored powerhouse, contains two turbine generating units with a total installed capacity of 280 kilowatts, and is located in the canal about 75 feet downstream of the headgate. Water used for generation discharges from the powerhouse into a 50-foot-wide, 400-foot-long tailrace (measured from the headgate to the tailrace outlet). Project power is transmitted through an existing 480-volt, 100-foot-long underground transmission cable. The Nashua River reach that is bypassed by operating the project (measured from the dam to the tailrace outlet) is about 300 feet long.

Ice House Partners operates the project in a run-of-river mode, and maintains a 1 million gallon per day flow (mgd) in the bypassed reach year-round via a notch cut in the flashboards.

The project is equipped with a real-time water level recording device to match turbine discharge with river inflow. When flow in the Nashua River is equal to or less than the hydraulic capacity of one turbine unit (160 cfs), no units would operate, and all inflow would spill over the flashboards. When flow exceeds 160 cfs, one turbine unit would begin generating and the excess would be spilled over the flashboards until such inflow exceeds an additional 160 cfs or 320 cfs (the hydraulic capacity of two units), at which time the second turbine unit would begin generating, with all flows over 320 cfs spilled over the flashboards.

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Certification History

August 21, 2014: The Ice House Hydroelectric Project has been recertified as low impact, continuing to meet the requirements of the Low Impact Hydropower Institute Certification Program. It will have a term of five years, effective August 6, 2014 and expiring August 6, 2019.

June 9, 2014: LIHI received a comment letter from the Massachusetts Division of Fisheries and Wildlife regarding the recertification of the Ice House Hydropower Project. The letter can be read in full in the “Files” section below.

April 23, 2014: The Low Impact Hydropower Institute received an application for a second term of certification of the Ice House Hydropower Project. The application materials are available in the “Files” section below.

October 22, 2009: The Ice House Project has been certified as low impact for a five year term, effective August 6, 2009 and expiring August 6, 2014.

August 6, 2009: Ice House Partners has submitted an application for certification of the Ice House Hydroelectric Project. The public comment period will remain open for 60 days.


Files: