Watersheds provide various ecosystem services including nutrient cycling, erosion control, water storage, recreation, and increased biodiversity. These services are essential to our social, environmental, and economic welfare. Human development has altered land use in many watersheds thereby affecting these services and stream health. Mill Creek sub-watershed is located in the eastern border of Ohio flowing north from Columbiana until it merges with the Mahoning River in Youngstown, Ohio. One of the major attractions is Mill Creek MetroPark which encompasses more than 4,500 of the 47,000 acre sub-watershed and 11 of the 24 miles of Mill Creek. Over the last few years, the Park has seen high E. coli counts, fish kills, and algae blooms which has prohibited recreational water activities and raised concerns. Land uses in the Mill Creek sub-watershed vary from residential to industrial, from agricultural to forested and recreational areas. This investigation attempts to identify the influence of surrounding land uses on water quality and stream health. Various physical, chemical, and biological water quality parameters were measured using standard methods. Water samples were taken from twelve locations along Mill Creek during low flow and 24-36 hours after significant rainfall events (>2 cm). Furthermore, macroinvertebrate sampling was performed seasonally.
Results/Conclusions
Rainfall increased E. coli concentrations in all sampling locations with a significantly strong positive correlation. There was a statistically significant, weak correlation between dissolved oxygen and E. coli. Higher concentration of bacteria leads to increase in biochemical oxygen demand and decrease in concentration of dissolved oxygen. Total solids also increased after rainfall, but the increase was not as large as E. coli increases. There was a statistically significant, although weak, negative correlation between ammonia and total solids. The overall average soluble reactive phosphate (SRP) is slightly lower after a rain event but do not seem to be greatly influenced by rainfall. Correlation coefficients indicate a weak positive correlation between SRP and E. coli. The reason for the weak correlation may be due to runoff, especially from agricultural land, which contributes fertilizer, animal waste, road side dust, etc. These can consist of higher concentrations of nutrients like phosphorous, as well as E. coli. This might also be the reason for the weak positive correlation between ammonia and SRP. Additional sampling may further elucidate the relationship between these variables and additional statistical tools are being used to investigate the ongoing connection of watershed land use practices and their impact on water quality.