Effects of Hydrographic Changes on Contaminants in Ohio River

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Abstract
The increase in the depth of the pool stage in the Ohio River to 26 ft, and the low stream flows (the lowest since 1895) during the summer and fall of 1962, 1963, and 1964 resulted in deterioration of water quality at Cincinnati. Because of the deeper pool and the sluggish flow, increased amounts of organic materials and trace metals accumulated in ooze deposits in deep pockets on the river bottom. Turbulence during short periods of increased flow caused resuspension of ooze material resulting in adverse effects on the biota and on their role in the self purification of the stream. Phytoplankton populations were reduced, resulting in lower production of dissolved oxygen (DO) from photosynthesis. During periods of high temperature and low DO, anaerobic conditions prevailed in these bottom depressions, degradation of organic matter in the deposits occurred, and trace metals complexed in the deposits returned to the water mass in solution or as colloids. This sequence of events, plus industrial wastes, perhaps, accounts for the periodic toxicity of the Ohio River water to plankton and, no doubt, played a role in the fish kills noted.