NITRATE DILUTION RATES WITHIN LITTLE CEDAR CREEK

This project aimed to determine the extent to which tributary pollutants affects a larger riverine system, specifically focusing on nitrate concentrations within Little Cedar Creek near Auburn, Indiana. Nitrate levels are tested and analyzed in both Little Cedar Creek and a drainage ditch which serves as the effluent water discharge of the water treatment plant of a nearby city. Testing was conducted twice in the Fall of 2022 (October & December). Measurements were taken at incremental distances from the mouth of the drainage ditch. We found that the nitrate levels spiked quickly, an increase of ~6 ppm, near the mouth of the drainage ditch. However, the spike was equally met by a steep decline in nitrate concentration shortly downstream. It appears perhaps the nitrate concentrations within Little Cedar Creek returned to near background levels within 40 meters. While the old adage “dilution is the solution” may seem supported by this evidence, there is significant evidence supporting that nitrate pollution from many sources deeply affect environments downstream.