To be certified as low impact, the projects had to meet or exceed eight key areas: river flows, water quality, fish passage and protection, watershed protection, threatened and endangered species protection, cultural resource protection, recreation, and facilities recommended for removal.
The Worumbo project, operated by the Miller Hydro Group, is located on the Androscoggin River at Lisbon Falls, Maine. The project consists of a dam/spillway, with a crest elevation of 97 msl which includes a gated flood spillway, an ogee spillway with 0.6m hinged flashboards, a center rock ledge section containing a concrete dike with 0.6m hinged flashboards, and a 158m long rock-filled timber crib dam with 0.5m high pneumatically operated crest gates; an intake section and integral powerhouse with two turbine generators units having a rated capacity of 19.4MW at an operating head of 9.3m. The crest gate/flashboard system is designed to fail when overtopped by 0.3m of water. The dam creates an impoundment with a surface area of 77ha at a normal full pond elevation of 98.5 msl.
The project is currently operated as a run-of-river project with outflow approximately equal to inflow on an instantaneous basis. The project is also operated to provide seasonally-varied minimum flow releases into the 259m 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 0.46m. Minimum flow release from the project are maintained at 48m3/sec or inflow, whichever is less, during impoundment refilling.
The Oswego project - operated by Brookfield Power - consists of six developments (Oswego Falls East, Oswego Falls West, Fulton, Minetto, and Varick developments) and comprises two FERC-licensed hydroelectric projects along the Oswego River in Oswego County, New York. The projects are all located at locks and dams owned by the New York State Thruway Authority Canal Corporation (NYSCC), operator of the State Barge Canal System.
The Oswego River is formed at the confluence of the Seneca and Oneida rivers and flows north approximately 23 river miles to Lake Ontario. The Oswego River first flows through the Lock 1 dam impoundment at the Phoenix Project (FERC No. 4113), which is owned by Algonquin Power. The water flow then enters the Oswego Falls impoundment formed by the Upper Fulton Dam (Lock 2, River Mile 12.6). The Oswego Falls East and Oswego Falls West developments (FERC No. 5984) are located immediately below this impoundment.
Once past the Oswego Falls project, water flow enters the Fulton-Granby impoundment. The Granby project (FERC No. 2837) and Fulton development (part of FERC No. 2474) are located at opposite sides of Lower Fulton dam (Lock 3), approximately 1.6km below Upper Fulton dam. The Oswego River next enters the impoundment formed by the Minetto dam. The Minetto development (FERC No. 2474) is located near Lock 5, approximately 10.3km downstream of Fulton and Granby. Next water flow enters the impoundment at Lock 6 and the High Dam project (FERC No. 10551), which is owned by the city of Oswego, with Erie providing operation and maintenance support for the plant. Finally, once past the High Dam project, water flow enters the Varick impoundment. The Varick development (FERC No. 2474) is located near Lock 7, 2.3km above the mouth of Lake Ontario.
For further information on the two projects, or any of the other projects certified by the LIHI, please visit www.lowimpacthydro.org.
