HYDROLOGICAL AND METEOROLOGICAL CONTROLS ON WATER QUALITY, ALLENS' CREEK, NORTH CAROLINA

The Allens' Creek Watershed, located in Haywood County, western North Carolina, supplies high quality drinking water for the town of Waynesville. The property has recently been placed in a conservation easement (2002) that permits limited forest management, with the contingency that activities pursued do not degrade water quality. Though the watershed is now protected, it has been the site of extensive logging operations during the past century. This study investigates the current water quality conditions of the watershed to (1) develop an understanding of the factors controlling water quality with special emphasis on documenting suspended sediment loads during storm events, and (2) determine how water quality has recovered following basin reforestation. Essential to this effort was the collection of continuous water quality data (e.g., turbidity, pH, discharge, total suspended solids) and documentation of the hydrologic and meteorological factors (e.g., storm intensity, storm duration, antecedent moisture conditions) controlling water quality. As expected, major variations in water quality were associated with storm events. The predominant controls on lag times and the magnitude of change in water quality, specifically turbidity, were maximum storm intensity and antecedent moisture conditions. High storm intensities and high antecedent moisture conditions resulted in shorter lag times due to rapid runoff production. High storm intensities resulted in the highest storm turbidity levels. Low antecedent moisture conditions provided a greater supply of easily erodible sediments, which contributed to higher storm turbidity levels than storms occurring during times of high antecedent moisture conditions. The character of sediment hysteresis loops suggests, however, that much of the sand-sized sediment load, monitored using automated samplers, is derived from bank erosion rather than upland areas.