Thermal loading is a cultural stress that occurs when human activities cause warm water to be discharged into cooler receiving waters such as rivers and lakes (Environment Canada 1993). This negatively affects the aquatic ecosystem by lowering the oxygen concentration of water and increasing the toxicity of many contaminants (Smith and Heath 1979; Felts and Heath 1984). Thermal discharges into Long Point Bay have increased due to 1) increased urbanization resulting in larger proportions of warm stormwater entering the Bay; 2) increased amounts of relatively warm sewage effluent entering the Bay; 3) increased discharge from industrial activities and power generation, such as at the Nanticoke Thermal Generating Station; and 4) and the presence of a substantial number of in-stream irrigation ponds within the Big Creek watershed wich cause an increase in stream temperatures (Dave Richards, personal communication). At present, the adverse affects of thermal loading are localized around the Nanticoke Thermal Generating Station (Haymes and Dunstall 1989). However, thermal loadings are additive, and increased industrial activities in the vicinity of Long Point Bay have the potential to adversely influence the Bay's ecological functioning.
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