RIPARIAN BUFFER EFFECTS ON STREAM CONTAMINATION IN THE CITIES OF MILLERSVILLE AND GOODLETTSVILLE, TENNESSEE

Three of the Cumberland River’s tributaries were placed on the Environmental Protection Agency’s 303(d) list, restricting them from being used for municipal water supply. Mansker’s Creek, Slater’s Creek, and Lumsley Fork were placed on the list in 2006 due to Escherichia coli measurements above maximum allowable contaminant levels, as well as for high siltation. Urban land use attributes to many sources of pollution such as storm water runoff, illicit discharges of sanitary wastes, runoff from the improper disposal of trash, leaky septic systems, and animals. The impaired streams watershed’s urban land use ranges from 1.7% to 68.7%, which can be problematic since impervious areas such as driveways, pavement, and rooftops allow storm water runoff to be directed to the streams much faster. This action gives the water little chance to infiltrate and percolate into the soil, taking away a filtering process before it reaches the streams. However, streams have an additional layer of protection called riparian buffer zones. These zones are vegetated areas adjacent to streams that are strongly influenced by the presence of water. Riparian buffers are important for good water quality since they prevent sediment, nitrogen, phosphorus, pesticides, and other pollutants from reaching a stream by filtration.

Aerial views of the streams were obtained from Google Maps to determine the extent of their riparian buffers. As a check to this data, portions of each of the three streams were walked to document the riparian buffer zones along the streams. Additionally, property zoning data was obtained for the properties adjacent to the streams, revealing whether the upland properties were residential, agricultural, commercial, etc. Weekly chemical analyses of the streams via seven total sample points were studied to determine the impact of the riparian buffers on stream chemistry. Results indicate that various types of riparian buffer zones were effective in removing nitrogen from nitrates and maintaining the overall health of the streams. However, effectiveness was directly tied to buffer zone width and type. The wider the buffer, the better it was at removing nitrogen and other pollutants. Also, the buffer type that allowed more microbial denitrification and plant uptake proved more effective.