The Worumbo Project is located on the Androscoggin River in Lisbon Falls and Durham, Maine.  The Worumbo Project is the third dam on the Androscoggin River, upstream from the Brunswick Hydroelectric Project (FERC No.2284) and the Pejepscot Hydroelectric Project (FERC No.4784).

Project Name Worumbo
LIHI Certificate Number 10
LIHI Effective and
Expiration Dates
March 3, 2013 to
March 3, 2018Eextended to 07/31/2018
Owner Brown Bear II Hydro, Inc
State Maine
Location Located on the Androscoggin River at Lisbon Falls, Maine.
Installed Capacity 19.4 MW
Average Annual Generation 93,364 MWh
Facility Type Run-of-river
FERC No. 3428

The Worumbo Project consists of a dam/spillway, consisting of a gated flood spillway, a concrete ogee spillway with crest elevation at 97 feet msl with two-foot-high hinged flashboards, a center rock ledge section containing a concrete dike with a crest elevation at 97 feet msl with two-foot-high hinged flashboards, and an approximately 520-foot-long concrete spillway with three independently operable pneumatic flasboard sections of seventeen (17) 2.17 ft panels, eight (8) 1.75 ft. panels, and twenty one (21) 2.25 ft. panels.  ; an intake section; and an integral powerhouse equipped with two (2) turbine-generator units having a rated total capacity of 19.4 MW at a net operating head of 30.5 feet.  The crest gate/flashboard system is designed to fail when overtopped by two (2) feet of water.  The dam creates an impoundment with a surface area of 190 acres at a normal full pond elevation of 98.5 feet msl.  The project is currently operated as a run-of-river facility, with outflow approximately equal to inflow on an instantaneous basis, with the exception of power system emergencies when Miller Hydro Group is called upon for maximum output.  The project is also operated to provide seasonally-varied minimum flow releases into the 850-foot-long bypassed river reach between the Durham-side dam and the end of the tailrace training wall.  Current operation permits the impoundment to be drawn down by a maximum of 1.5 feet to allow the owner to maximize the energy and capacity of the project, to provide short-term reserve capacity to the interstate power grid, and to provide ancillary services (i.e., Automatic Generation Control) to the power grid under deregulated market conditions.  Minimum flow releases from the project are maintained at 1,700 cfs or inflow, whichever is less, during impoundment refilling.

Certification Benefits

The clean energy benefits of the Worumbo facility are the generation of more than 93 million kWh of electricity per year, plus ancillary benefits to the stability of the electrical transmission system.  Using current U.S. EPA data for typical household electricity demand, that annual generation is enough to supply electricity to approximately 8,100 homes. In addition to these energy benefits, the Worumbo facility provides important ecological benefits to the Androscoggin River by maintaining minimum flows to protect fish habitat in the facility’s bypassed reach, by operating fishways to enable fish passage, and by being an active partner in restoring Atlantic salmon runs.

Certification History

March 13, 2018: The Worumbo Hydroelectric Project has been granted an extension of the current term through July 31, 2018.

August 27, 2014: The Worumbo Hydroelectric Project has been certified as low impact for a third five year term, effective March 3, 2013 and expiring March 3, 2018.

May 5, 2014: The certificate term for the Worumbo Project has been extended by the Executive Director to June 30, 2014, in order to allow time to finalize the review of the application for recertification.

May 23, 2013: The Low Impact Hydropower Institute has received an application for recertification of the Worumbo Project.

July 3, 2008: The Worumbo Project was recertified for a second five year term. Miller Hydro Group requested to have the expiration date of their current certification accelerated and to file right away for a renewal of their project. The request was accepted and the existing certificate will expire on the effective date of the new certificate.

May 24, 2004: The Worumbo Project was certified as low impact for a five year term, effective February 19, 2004 and expiring February 19, 2009.


2013 Recertification