Entrainment and Impingement of Fish by Power Plants in the Great Lakes which use the Once-Through Cooling Process

There are 89 thermal electric generating stations, producing 54,118 Megawatts (Mwe) of electricity, which use water directly from the Great Lakes. Electrical production per capita in Canada, 3.34 kw, is about twice that of the United States, 1.32 kw. These power plants require almost 2000 m3 s−1of cooling water or, conservatively, >30% of the flow of the St. Lawrence River. Cooling water use is directly related to Mwe production and 176 L are required per kilowatt. The majority (76%) of power plants cause temperature increases of 12° C or less. Impingement of fish is directly related to power plant size (log10 number impinged = 0.414 + 1.844 log10 Mwe capacity) and we calculated that more than 100 × 106 fish will be lost at existing and proposed stations. Impingement results in direct losses to the fishery of more than 25%, by weight, of the annual commercial fish harvest. Entrainment is also directly related to power plant size (log10 number entrained = 2.103 + 1.658 log10 Mwe capacity) and we expect more than 1.28 × 109 larval fish will be lost by entrainment. These estimates of entrainment and impingement are conservative since they are based upon rated pumping capacity, not actual usage which was 67% for the few plants that provided this information. Impingement losses, when combined with entrainment losses which will affect recruitment to some unknown degree, likely constitute a significant undersirable impact upon the Great Lakes fishery.