Effects of forest harvesting best management practices on surface water quality in the Virginia coastal plain

Three small watersheds located in Westmoreland County, Virginia, were monit ored to evaluate the impact of forest clearcutting on surface water quality and to evaluate the effectiveness of forestry best management practices (B MPs) for minimizing hydrologic and water quality impacts associated with ti mber harvesting. One watershed (7.9 ha) was clearcut without implementation of BMPs, one watershed (8.5 ha) was clearcut with the implementation of BM Ps and a third watershed (9.8 ha) was left undisturbed as a control Forest clearcutting without BMP implementation reduced storm runoff volume and did not significantly change peak flow rates. Following site preparation, both storm flow volumes and peak flow rates decreased significantly. For the wa tershed with BMP implementation, storm flow volume decreased significantly following harvest, while peakflow increased. Site preparation did not chang e storm flow volumes over post-harvest conditions, bur did significantly re duce storm peak flow rates. Disruptions in subsurface flow pathways during harvest or rapid growth of understory vegetation following harvest could ha ve caused these hydrologic changes. Harvest and site preparation activities significantly increased the loss of sediment and nutrients during storm ev ents, Storm event concentrations and loadings of sediment, nitrogen, and ph osphorus increased significantly following forest clearcutting and site pre paration of the No-BMP watershed. Both the BMP watershed and the Control wa tershed showed few changes in pollutant storm concentrations or loadings th roughout the study. Results of this study indicate forest clearcutting and site preparation wit hout BMPs can cause significant increases in sediment and nutrient concentr ations and loadings in the Virginia Coastal Plain. However these impacts ca n be greatly reduced by implementing a system of BMPs on the watershed duri ng harvesting activities.