Influence of urban and agricultural land use on forested watersheds

Forested watersheds provide high-quality water supplies to over half of the western U.S. population. Yet these watersheds are vulnerable to disturbances such as wildfire, insect outbreaks, and atmospheric pollution. A Land Change Science-funded project, Connections between Forested and Urban Landscapes and Implications for Water Supply, is working to understand how forested water-supply watersheds are impacted by nearby urban and agricultural land use. Ion-exchange resin columns are deployed across an urban-forest transect in and near Boulder, Colorado to collect atmospheric nitrogen, an indicator of pollution from urban and/or agricultural activities that can affect nutrient cycling and water quality. The resins are extracted in the laboratory, as shown here by Toby Halamka, a USGS student contractor working with USGS Research Hydrologist Sheila Murphy and USGS Microbiologist Deborah Repert in Boulder. These data will be used to better define the footprint that urban and agricultural land use leaves on forested watersheds, and how this affects water supply.