DYNAMICS OF NITRATE, PHOSPHORUS, AND SUSPENDED SEDIMENT TRANSPORT IN TWO AGRICULTURAL STREAMS IN CENTRAL ILLINOIS

Nutrients such as nitrate and phosphorus are necessary for plant life, but excessive amounts can be detrimental. Large amounts of nutrients entering bodies of water can lead to hypoxic zones such as the one in the Gulf of Mexico. Nutrients are also problematic in drinking water reservoirs, as high concentrations of nitrate in drinking water can cause health conditions such as blue baby syndrome. High nutrient concentrations are a reoccurring problem in the drinking water reservoirs for the City of Bloomington, Illinois where water is drawn from two reservoirs – Evergreen Lake and Lake Bloomington. The primary source for these nutrients is from agriculture, which dominates the land use in the area. To better understand the dynamics of nitrate, phosphorus, and suspended sediment being transported into these reservoirs, water samples are being collected bi-weekly at the major tributary for each reservoir. Six Mile Creek is the major tributary for Evergreen Lake and Money Creek for Lake Bloomington. Water samples are analyzed for nitrate and total phosphorus concentrations using flow injection analysis (FIA). Suspended sediment concentrations are also being examined, as it can be an indicator of pollutants and a means of nutrient transport. Initial results show high nutrient and suspended sediment concentrations in both creeks during or just after rain events, when discharge is high. Total phosphorus concentrations generally follow rain patterns closely, while nitrate is high year round and does not increase as much during rain events. Nitrate concentrations have sometimes been found in concentrations above the EPA drinking water limit of 10mg/L. This study will provide the City of Bloomington with information about how much, and when the most nutrients are entering their drinking water reservoirs and allow them to take the appropriate steps to improve their water management.