Abundance and Composition of Fish and Shellfish Impinged and Entrained at Power Plant Intakes Based on a Survey of Over 220 Power Plants

In response to EPA’s 2004 Phase II 316(b) Rule, most of the nation’s once-through power plants conducted impingement and, where required, entrainment studies, hereafter referred to as IM&E.  EPRI determined that the data collected during these studies represented a unique opportunity to characterize IM&E at the nation’s power plants.  A web-based survey was used to collect information including plant location and operating characteristics, sampling methodology and, most importantly, IM&E results.  Responses were received from 240 plants representing approximately 56% of the in-scope facilities.  Results were stratified by both geographic area and waterbody type (e.g., estuaries, oceans, large/small rivers, the Great Lakes, reservoirs).  Initial compilation of the data indicates that IM&E vary widely.  Estimated annual impingement losses ranged from less than 1000 fish to approximately 70 million fish.   Estimated entrainment losses ranged from zero eggs and larvae per year to approximately 36 billion organisms per year.  It was found that clupeids (threadfin shad in the southeast and the southwest and gizzard shad elsewhere) dominated impingement at most freshwater plants. Impingement results differed greatly among East Coast plants, those on the Gulf Coast, and those in California.   White perch, blue crab, Atlantic croaker, and bay anchovy were the most commonly impinged organisms at coastal areas, except the West Coast.  Entrainment results also differed widely depending on region and waterbody type. Few threatened or endangered species were collected in impingement or entrainment samples.  It was found that only a small percentage of these plants have any fish protection devices in place.  There were little or only weak relationships between IM&E rates and plant size, which is a reasonable surrogate for pumping rate.  We concluded that both IM&E rates and composition are determined by unknown site-specific or, at most, region-specific factors.