ASSESSING THE WATER QUALITY IN BIG FISHING CREEK WATERSHED IN RELATION TO THE TMDL FOR THE CHESAPEAKE BAY

Agricultural non-point source pollution is the leading source of water-quality impairment to many of the nation's rivers, lakes, and estuaries, including the Chesapeake Bay. A TMDL plan was developed by the US EPA in 2010 to reduce nutrient and sediment loads for the Bay. The agricultural sector in Pennsylvania portion of the Bay watershed did not meet the interim target set in the TMDL in 2017.

Detailed data, addressing the spatial and temporal variations in nutrients and suspended sediment, are essential in order to characterize small, rural watersheds and thus generate effective BMPs and TMDLs for higher-order streams. A base-line data collection was carried out during 2002-06 focusing on nutrient and sediment flux within the Big Fishing Creek watershed in Clinton County, PA, which is a major tributary to Bald Eagle Creek, which, in turn, flows into the West Branch Susquehanna River, and ultimately to the Chesapeake Bay. A follow up data collection was done during June-September in 2018. The results of this two-phase water quality analysis was used to evaluate relative contribution of nutrients and sediments loads by Big Fishing Creek watershed to the Chesapeake Bay watershed. Eleven water quality parameters were tested on ten locations along Big Fishing Creek and in several tributaries. These parameters included pH, Conductivity, Temperature, DO, BOD, TSS, NO₃-N, NO₂-N, NH₃-N, Total Phosphorus, and COD. These parameters were used to calculate a Water Quality Index score on a scale of 0 to 100.

The results of these two studies indicate the following: (1) high nitrate and phosphate concentrations correlate to both specific point as well as non-point sources; (2) the Big Fishing Creek watershed contributes to nutrient and sediment loads of the Chesapeake Bay watershed at a much higher rates than the average values observed by the Susquehanna River Basin Commission at locations that are situated upstream and downstream of this study area; and (3) for the Chesapeake Bay TMDL plan to succeed, the landuse practices in watersheds for the first and second order streams that are dominated by agriculture and karst topography need to be targeted for implementation of BMPs.