The economic efficiency of watershed management concerning drinking water supply in the White Clay Creek watershed in Pennsylvania and Delaware
Date
2005
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Publisher
University of Delaware
Abstract
The White Clay Creek watershed in northern Delaware and southeastern Pennsylvania is the drinking water supply to the city of Newark, Delaware. This thesis 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 occur at a fast pace. A land use analysis on the Pennsylvania and Delaware sections of the White Clay Creek watershed had found that impervious cover in the watershed increases at a rate of one half percent annually and is currently eleven percent for the area of the watershed that contributes source water to the city of Newark. Land use 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, and this thesis measures the range of sensitivity and the economic impact that declining water quality will have on the operation of the facility run by the Newark Water Department. 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. ☐ The Curtis Mill Water Treatment Plant can physically and financially upgrade to the 40 NTU operating limit. This thesis has found that 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. ☐ This research has produced three specific recommendations regarding the Newark Water Department. ☐ It is recommended the Newark Water Department remain active in watershed management groups within the White Clay Creek watershed and greater Christina River basin. The Newark Water Department would work with the management groups to slow the rate of land use conversion in Pennsylvania. ☐ The second recommendation advocates the investment by the City of Newark in a real time turbidity meter. The turbidity meter will enable an exact study of the turbidity streamflow relationship that was extrapolated in this research. ☐ The turbidity meter will enable the Newark Water Department to fulfill the third recommendation which is to develop a new chemical dosage schedule for the Curtis Mill Water Treatment Plant that will raise the operating limit from 20 NTU to 40 NTU. A 40 NTU operating limit will expand the range of turbidity the Curtis Mill Water Treatment Plant can technically handle. A higher operating limit will reduce financial losses that accrue to the Newark Water Department because the practice of purchasing water from United Water Delaware is more expensive than treating water during high turbidity.