Environmental Changes in a Polluted Stream During Winter

Abstract

Year round studies of environmental conditions in Lytle Creek, a stream polluted with organic wastes, were initiated late in 1949, by the Biology Section of the Public Health Service's Environmental Health Center.2 Lytle Creek is a tributary of the Little Miami River which enters the Ohio River at Cincinnati. It is about 11 miles long, and has an average width and deptl of 15 feet and 1 foot respectively, during normal summer flows. Widths range from 3 to 35 feet and depths from a few inches to a maximum of 6 feet. Surface runoff comprises the major portion of the natural stream flow. During the summer months the stream has only one functional tributary below the outfall from the primary sewage treatment plant of the city of Wilmington which contributes 80 to 90 percent of the total stream flow. This large amount of organic waste quickly blots out normal stream conditions in the summer and a deinite septic zone is established below the sewage outfall. However, all well recognized pollutional zones are established and the stream retums to essentially clean water conditions before it joins Todds Fork of the Little Miami River. The aims of the Lytle Creek Study were to relate environmental conditions in various portions of the stream to the qualitative and quantitative composition of the aquatic population found in these sections; to observe seasonal changes in the fauna and the environment; and to collect other related data essential for the correlation of past ecological conditions with the composition and abundance of the aquatic fauna. The Lytle Creek investigation is one phase of an overall study designed to develop a biological method which can be used throughout most of the year and in most streams for indicating the polluti,onal conditions due to organic wastes which have prevailed over a considerable period in the past. Such a method would be desirable in reconnaissance surveys for indicating the severity and extent of organic pollution and the degree of stream recovery. Ecological cond'itions and the composition of the fauna of Lytle Creek during spring and summer have been described by Gaufin and Tarzwell (1952). Fall and winter conditions have also been studied during the past two years. These investigations have followed the movement of ecological or pollutional zones in the stream with the seasons and with changes in flow. Under summer conditions the stream has only one functional tributary below the source of pollution. During the winter months, however, several tributaries support a varied and abundant fauna which is contributed to the