HEAVY METAL INDICATORS OF POLLUTION OF A SMALL SUBURBAN WATERSHED IN CEDAR FALLS, IOWA

Dry Run Creek watershed is the major drainage system in northwestern Black Hawk County, Iowa. It covers an area of approximately 15,200 acres with nearly 24.5 miles of stream channel. The watershed was listed on Iowa’s impaired water list in 2002 and 2004. The creek is fed by runoff water from agricultural fields as well as streets and parking lots. In recent years, some segments of the creek have been diagnosed with excessive amounts of E.coli and nitrates. Studies have indicated that land use activities associated with agriculture and urban development are primarily responsible for deteriorating water quality in the creek. Water quality tends to vary between urban and rural sites in response to the amount of rainfall indicating that though agriculture has always been identified as a source of water pollution over the last few years, urbanization is becoming an increasingly important contributing factor. This study focused on the accumulation of heavy metals in the Dry Run Creek sediments that are potentially toxic to the living environment. Water and sediment samples were collected four times from nine different locations in the creek. These sediments were analyzed using x-ray fluorescence for the following elements: As, Cd, Cr, Cu, Ni, Pb, and Zn. The goal of this project is to use metals in sediments as indicators of land use activities in urban versus rural areas. The results will allow us to find potential hot spots of pollution in this small but very important tributary system of the much larger Cedar River in the area.