Forecasting the impacts of future development on water quantity and quality within the Reedy River Watershed. (March 2015) - Privette, C.V.
Highlights: Peak flow at Boyd Millpond and Lake Greenwood increase by 23% and 15% for 5:1 growth. TP and TN increase 86% and 39% for a 5:1 growth scenario at Lake Greenwood. TP and TN increase 39% and 17% for a 1:1 growth scenario at Lake Greenwood. TP and TN increase 52% and 28% for a 5:1 growth scenario at Boyd Millpond. TP and TN increase 28% and 14% for a 1:1 growth scenario at Boyd Millpond. Abstract: This study was initiated to gain a better understanding of how patterns of development within Greenville, SC and its surrounding metro area would affect the Reedy River's water quantity and quality. Grenville County is located in the Upstate of South Carolina and serves as an economic hub for this region. Greenville is located on the I-85 corridor halfway between Atlanta, GA and Charlotte, NC. A previously prepared watershed-scale model was modified to yield quantity and quality data that would result from projected growth in Greenville through year 2030 at three different growth scenarios. The major findings of the study showed water quality was degraded with higher nutrient loads and peak and average flows were consistently higher for sprawling as compared to compact development. As more land is developed in the sprawling scenario, the amount of stormwater increases while water quality decreases. At Boyd Millpond by 2030, for instance, change in peak flow and average flow percentages more than double for the sprawling scenario. Similar effects were also seen for both total phosphorus and total nitrogen levels. Results are similar by 2030 for the flow entering Lake Greenwood from the Reedy River Arm. At that location, change in peak and average flow percentages, and changes in total nitrogen and phosphorus percentages, more than double when comparing sprawling versus compact developments. While these results are based on the effects of predicted development along the Reedy River, in Greenville, SC, the overall implications of development on water quality applies to most any community faced with similar issues. These modeling results allow land use planners such as municipal boards to gain a better understanding of what impacts land use planning and zoning can have on a community as related to effects on water quality and quantity.