Environmental Impact of Impoundment of the Snake Creek Reservoir Keith Rice, Bryan Victor, Dr. Julie K. Bartley, and Dr. Rebecca Dodge; Department of Geosciences, University of West Georgia, Carrollton GA Landsat Satellite Images Water Quality Upstream-Site 49 Downstream-Site 111 Unsupervised Classifications 2001 Change Detection Background The Snake Creek Reservoir was impounded in late It is located just east of Carrollton Georgia and provides part of the county’s drinking water supply. It is the newest and largest reservoir in Carroll County. Concerns Temperature will increase in flooded areas, due to decreased flow and increased surface area. Turbidity will increase due to upstream erosion. The reservoir will gradually fill with sediments. Dissolved oxygen levels will become lower and may result in a fish kill, upstream of the reservoir. Bacterial activity will increase. Project Goals Assess environmental and water quality change during and after impoundment. Data sources: Landsat satellite (1999, 2001, 2003); water quality data from the Center for Water Resources (2001, 2004), and from USGS (2001), and newly collected data during the project. These three scenes capture the intervals of the reservoir impoundment. The central portion of the subset, shows substantial change from 1999 to 2001 and again from 2001 to (Green represents vegetation; pink shows areas of bare ground; and black represents water) The image is km wide. These images evaluate change between two time intervals. Green represents a ≥20% increase in reflectance and the red shows a ≥20% decrease in reflectance. Black areas show <20% change. The 1999 image was taken during a drought, causing change to appear anomalously high. Conclusion Satellite images show substantial change over the study period. Pre- impoundment clear cutting and subsequent impoundment are visible. Water temperature increase upstream of the reservoir contributes to a drop in dissolved oxygen. Upstream increase and downstream decrease in turbidity is consistent with sediment erosion and entrapment in the reservoir. Over time, the reservoir will accumulate sediment, decreasing its volume. Fecal coliform bacteria levels show a pattern similar to turbidity, consistent with increased runoff and higher temperature upstream of the reservoir, and entrapment of sediment in the lake. The images above group areas of similar land cover to better visualize land use change from year to year. Green=Grass, Orange=Bare Ground, Turquoise=Evergreen Trees, Dark Green=Deciduous Trees, Blue=Water, Pink=Residential, Red=Roads, and White=Clouds Acknowledgements: John Congleton, Randa Harris, Curtis Hollabaugh, Patrick Gilliland and Andrew Boothe. Funded by: NSF STEP grant # DUE Temperature is higher after impoundment at both sites. After impoundment, summer water temperature exceeds air temperature. Average turbidity is higher upstream after impoundment and lower downstream. Note that clear-cutting had begun in the reservoir area by Dissolved Oxygen is lower after impoundment, upstream of the reservoir. Fecal coliform bacteria levels are higher upstream after impoundment and lower at the downstream sites (site 50 is downstream from site 111).