Interfaces of Steam Electric Power Plants with Aquatic Ecosystems

Growth and reproduction may be stimulated by increased temperature in the cooling system and thermal plume during seasons when ambient water temperature is less than optimum, but growth, reproduction and survival are reduced when the elevated temperatures become excessive. Some fish species congregate in the warm thermal plumes during cold seasons but are excluded from this living space by temperatures above their preference in the summer. However, the warm refuge provided by a thermal plume in cold seasons can be a death trap if a power plant shuts down suddenly and exposes the fish to cold shock exceeding their lower thermal tolerance limits. Each of the factors tend to affect different segments of the biota. For example, impingement involves primarily juvenile and adult life stages of fish and species of large invertebrates; pumped entrainment affects are restricted to the smaller planktonic forms that include egg and larval stages of fish; and chemical and thermal discharges may affect all segments of the biota but in ways that vary dramatically among segments, species or even life stages of a species