LEWIS SMITH LAKE - Auburn University

etween 10 and 15 mgIL as CaCO, but occasionally fell below 10 mgIL. Any acid contamination of
Smith Lake will further reduce total alkalinity and pH will decrease. As pH declines below 6.5 fish
growth rate slows, at a pH ofabout 5.0 reproduction ceases and below pH ofabout 4.0 fish die (Boyd
1979). Other aquatic organisms react in a similar way although some are not as tolerant as fish to low
pH. Some valuable fish food organisms begin to disappear below pH 6.0 (Mayer et al. 1984). Indirectly,
low pH can result in higher concentrations ofheavy metals that become toxic to fish and wildlife. At
higher hydrogen ion concentrations metals bound in soil and sediment are mobilized to the water where
they can be accumulated by the biota (Mayer et al. 1984). In the 1986 Smith Lake study (Bayne et al.
1987) concentrations ofchromium, copper, iron, manganese and zinc exceeded critical levels considered
acceptable by the U. S. Environmental Protection Agency (EPA 1986).
Smith Lake usually met the pH criteria (6.0-8.5) for waters use-classified as fish and wildlife by
the Alabama Department ofEnvironmental Management. However, most ofthe water column pH values
were