Watershed Management and Drinking Water Supply in the White Clay Creek

The White Clay Creek watershed in northern Delaware and southeastern Pennsylvania is the drinking water supply for the city of Newark, Delaware. The paper is an analysis of current and future water quality and land use changes as they relate to the operation of the Curtis Mill water treatment plant that withdraws surface water from the White Clay Creek. The research is based on the interaction of watershed management, water supply operation, and water quality as they pertain to drinking water. The water quality of the White Clay Creek is currently high, but land use changes known to be detrimental to water quality within the watershed are occurring at a fast pace. A land use analysis on the Pennsylvania and Delaware sections of the White Clay Creek watershed found that impervious cover in the watershed is increasing at a rate of 0.5 % annually and is currently 12 % for the area of the watershed that contributes source water to the city of Newark. Land us change is most apparent in the transition from agricultural land to single family residential areas. The Curtis Mill water treatment plant is technologically sensitive to stream turbidity. The plant currently purchases water from United Water Delaware when stream turbidity in the White Clay Creek surpasses 20 NTU. Given the increase in turbidity frequency and intensity due to estimated impervious cover growth, an upgrade to a 40 NTU operating limit is recommended. It can physically and financially upgrade to the 40 NTU operating limit. The analysis found it is cheaper for the plant to treat water with turbidity between 20 NTU and 40 NTU rather than purchase it from United Water Delaware under current high water quality and future poor water quality conditions.