Impact Of Land Use On Water Quality Of Mill Creek Watershed In The Mahoning Valley Ohio

This is a study of the influence of the various land use practices on water quality parameters of Mill Creek Watershed that flows north from Columbiana County, then through Boardman Township and Mill Creek Park, before finally merging with the Mahoning River in Youngstown, Ohio. Land uses in the Mill Creek sub-watershed vary from residential to urban industrial as well as from agricultural to forested and recreational areas. Water samples were collected from eleven different points of Mill Creek. Various physical, chemical and biological water quality parameters like temperature, DO, pH, ammonia, soluble reactive phosphorous, nitrate-nitrogen, TSS, VSS, TDS, VDS, Total Coliform, E.coli and BOD were measured using standard methods. Graphical representations showed the difference in the averages of different water quality parameters before and after rain events. Inverse distance weighted (IDW) interpolation techniques were used to represent the spatial dispersion of nutrients, solids and bacteria at the scale of whole watershed. Different types of land cover i.e., herbaceous land, forest, developed areas, cultivated crops, open water and wetlands of Mill Creek Watershed are used in this study. Principal Component Analysis (PCA) of water quality parameters shows a positive correlation of the potential runoff from impervious surfaces and cultivated land with the concentrations of ammonia, TSS, E.coli, VSS and Coliform. On the other hand, percentage of forest does not depict any trend with the concentrations of ammonia, TSS, E.coli, VSS and Coliform. Principal Component Analysis with whole data covering 2016-2018 indicate that the high precipitation events in summer 2016 diverged from high precipitation events in the fall. Excluding the high precipitation events from summer of 2016 results implications that are similar to that of 2017-18. Thus, high precipitation events of summer 2016 apparently produced water parameters similar to that of low flow conditions. This study shows that the runoff from cultivated land and impervious surfaces has negative impact on the water quality of the watershed. Beside runoff from impervious surfaces and cultivated land, input of nutrients, bacteria and solids from the tributaries of the Mill Creek River might be contributing to reduced water quality in Mill Creek River. It is recommended to expand the sampling into the tributaries of the Mill Creek River.