Differences in Surface Water Quality Draining Four Road Surface Types in the Southern Appalachians

Improved and unimproved roads can be the primary source of stream sediment in forested watersheds. We assessed differences in production of total suspended solids (TSS; ppm) from four road surface conditions in a Southern Appalachian watershed: (1) a 2-yr-old paved surface (P), (2) an improved gravel surface with controlled drainage and routine maintenance (RG), (3) an improved gravel surface with erosion and sediment control structures installed and routine maintenance (IG), and (4) an unimproved poorly maintained gravel surface (UG). Variation was high among and within road surface types. The P surface generated the least amount of TSS, which was comparable to control sites, while the UG surface generated the most. The P surface produced significantly less TSS than the UG surface, but not less than the IG and RG surfaces. Variation among road surface types was related to TSS travel distance below the road, precipitation amount, time of year, and the existence of functioning erosion and sediment control structures. TSS decreased with travel distance (P = -81% over 38.5 m, IG = -30% over 30.5 m, RG = -89% over 39.4 m, and UG = -22% over 28.1 m). Also in this study we assessed the delivery of total petroleum hydrocarbons (TPH; ppm) from the P surface and found concentrations of < 0.5 ppm, which are well below published USEPA and NC DENR TPH standards for sediment. Paving is an attractive option for reducing maintenance costs and sediment production and transport; however, levels of TPH from freshly applied asphalt are unknown. South. J. Appl. For. 27(2):100–106.