Hydroelectric, Wachusett - MWRA also operates hydroelectric generators where the drinking water enters and leaves the Wachusett Reservoir. At Oakdale, a 3.5 MW turbine generates 13 million kilowatt hours per year and at Cosgrove, two 1.7 MW turbines generate 3 million kilowatt hours per year and provide an annual revenue from electrical sales of $1.1 million.