Fish Distribution and Abundance Below a Southeastern Hydropower Dam

Releases of large volumes of water from low-level release ports during generation of peaking hydropower at Hartwell Dam, Georgia-South Carolina, resulted in large daily flow fluctuations and altered water quality in a section of the Savannah River. Flows ranged from a minimum of 3 m3/sec during nongeneration to 665 m3/sec during generation. Thermal stratification in Hartwell Reservoir generally resulted in low water temperatures (≤20 C) throughout the 14-km study area and low dissolved oxygen concentrations <3 mg/I) in the 2-km section of the river immediately below the dam. Distribution of fish species was similar at all sampling locations, but abundance generally increased downstream. Major factors affecting fish abundance below Hartwell Dam appeared to be recruitment of fish from the reservoir, a reduction in habitat diversity just below the dam, water temperatures suitable for sunfish spawning, and stocking of rainbow and brown trout (Salmo gairdneri and S. trutta).

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