Degree Name

Master of Science (MS)

Semester of Degree Completion

1993

Thesis Director

Charles L. Pederson

Abstract

The Charleston Side Channel Reservoir (CSCR) is located on the southeast edge of the City of Charleston in Coles Co., IL. The CSCR is the sole source of public drinking water for the city and also provides for a variety of recreational activities. Water quality in the CSCR has deteriorated since its construction in 1981, leading to its classification as hypereutrophic. The presence of high levels of phosphate are of particular concern having contributed to an increase in algal blooms and high turbidity.

In order to assess the role of internal loading of phosphate from the sediment, thirty-five sample sites were evaluated for total phosphate and composition. Samples were ashed at 240 C and all analyses were conducted according to standard methods (APHA, 1985). In addition, the type of sediments most likely to release phosphate into the water column were also examined.

Most of the sediments containing high to intermediate levels of phosphate were found in shallow areas adjacent to drainage areas or situated where the peninsula was located. Multiple regression analyses showed a weak positive relationship between percent clay composition and phosphate concentration. The results of this study indicate that internal phosphorus loading constitutes an important source of phosphate in the CSCR. Dredging is a potential remediation method which would serve to eliminate the phosphate-laden sediments and deepen the CSCR. Limiting the removal of sediments in the areas of high to intermediate concentrations would lower the cost of dredging. However, methods must also be employed to control erosion thereby ensuring improved water quality and preventing renewed deterioration.

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