HYDROLOGY OF LAKE CONESTEE’S WEST BAY: AN EMERGENT WETLAND SOUTH OF GREENVILLE, SOUTH CAROLINA

Lake Conestee, located six miles south of Greenville, South Carolina, is an old mill pond formed by the damming of the Reedy River in 1832. Excessive sedimentation related to industrialization and urbanization throughout the nineteenth and twentieth centuries has resulted in an emergent wetland system with complex hydrologic dynamics. In particular, the West Bay region of the lake undergoes complete reversal of flow during large rain events. This study involves using water elevation and precipitation data in order to better understand this dynamic system during periods of drought and large rain events within the watershed. The primary focus is on the function of the West Bay as a means of storm-water mitigation during large rain events within the Reedy watershed in which the river reverses flow in the two exit sloughs of the West Bay, causing backflow into the system. The West Bay is fed from the east by Marrow Bone Creek and feeds into the Reedy River via its two exit sloughs, the north slough and the old river channel. Water level gauges periodically measuring stage height were set up at four locations in the West Bay area. Each of these stations was surveyed relative to mean sea level. During the time of study, there were several “out-of-bank” events in which the Reedy River began to backflow into the West Bay. These events generally occurred when rainfall over a 24 hour period exceeded 2’’ across the more rural upper reaches of the watershed, 1.5-2’’ over the urban landscape of downtown Greenville/Woodruff Road area, or a combination of the two. These were rain events in which the USGS gauge 02164000, located two miles north of the West Bay, rose to a stage height of greater than 5.5 feet. These events resulted in walls of water traveling down the Reedy River topping the banks of the West Bay impoundment of Lake Conestee with nearly 27,000,000 gallons of water during the larger events. This study shows the efficiency of the West Bay at mitigating storm-water runoff and provides a better understanding of the hydrologic system and the conditions that cause these backflow events to occur. Understanding this system informs the storm-water managers for the city and county of Greenville and helps Lake Conestee Nature Park as they plan for infrastructure improvements and in their educational outreach to visitors on the dynamic nature of this system.