Assessing the Effects of Unpaved Roads on Lake Champlain Water Quality

University of Vermont (2013). Assessing the Effects of Unpaved Roads on Lake Champlain Water Quality (Final Report). Grand Isle, VT: Lake Champlain Basin Program.

• Dataset 1

The studies described in this report were motivated by an interest in understanding the role of roadside drainage on water quality impairment in the Lake Champlain Basin. The Basin encompasses a 21,326 km2 (8,234 mi2) mostly rural land area, with farmland occupying much of the lowlands and forests in the uplands. Monitoring and research within the Basin to date have improved our understanding of the role of agricultural and urban storm water runoff on water quality. Little is known about the effects of the extensive transportation network, especially the network of unpaved roads in the uplands, on water quality. This project was initiated to improve that understanding. We undertook two studies to quantify pollutant (suspended sediment and phosphorus) production from the transportation network in the Winooski River watershed. We focused on unpaved roads, which dominate the transportation network in the rural uplands and which
have been shown in studies from other regions to have important water quality impacts. Within the Mad River watershed, we monitored a set of 12 road segments during summer and fall of 2011 and during spring and summer of 2012. We measured runoff and collected water quality samples during storm events, and quantified the mass of suspended sediment and total phosphorus produced on roads at these sites. We used these observations to scale up to the catchments in which these roads were located, and used monitoring data from the local watershed association to contextualize our estimates of catchment-scale road runoff. Within the Winooski River watershed, we surveyed nearly 100 km of unpaved roads to inventory the type of size of erosional and depositional features evident on roads and to assess the efficacy of best management practices on erosion reduction. We used the inventory to scale up to the entire unpaved road network in the Winooski watershed, and used estimates of sediment and phosphorus loadings from long-term monitoring programs to contextualize our results.