Middle Creek Water Assessment Using Water Quality Index (WQI)

Abstract

Water quality Index (WQI) provides a single value to express overall quality of water which is calculated based on a number of measurable parameters. WQI was calculated based on 10 parameters that were determined during the period between June and July of 2012 and July of 2013 in an effort to assess the water quality of Middle Creek (MC) (Snyder, CO. PA). The Middle Creek (MC) is a 2nd order tributary stream flowing into Penn's Creek before joining the Susquehanna River. In this study, eleven sites were selected along MC between the head waters and its confluence with Penn's Creek. Physical properties were measured in the field, and grab-samples were tested for P, NO2−, NO3−, NH3, biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total suspended solids (TSS). The Composite WQI for all sites along MC was calculated to be 89.71, indicating that MC is in good condition regarding water quality and is capable of buffering nutrient and chemical runoff. Results have shown that certain parameters, such as temperature (T°), COD or BOD, can be used as proxies for predicting the WQI. Due to good correlation with WQI values, T°, COD or BOD can be used to assess water quality within a short period of time. In this study, T° and COD were found to give the best forecasting parameters, followed by BOD. The relationships found between WQI and these three parameters, allow for a simple test to provide an adequate assessment of the water quality of a given stream system.