Technical Abstract: Agricultural Best Management Practices (BMPs) for grazing farms such as streambank fencing, cattle crossings and conservation buffers are intended to reduce sediment and nutrient movement into streams, but the effects of these practices are difficult to measure. A large interdisciplinary team is examining the long-term effects of these BMPs in the Spring Creek watershed of central Pennsylvania. One of the three subwatersheds is mostly forest, with little agriculture. A second subwatershed had BMPs applied to 98% of the agricultural lands in the mid-1990s. The third subwatershed had a smaller proportion of treated area. Data on water quality, fish abundances and stream invertebrates were collected in 1991-2 before treatment, 1999-2003 after treatment, and in 2007-2009 to assess long-term effects. BMP placement effects - are some sites more effective than others? - are being studied using high-resolution aerial data. The third component is a social and economic analysis of attitudes toward BMP installation, maintenance, or abandonment. This project is ongoing, but preliminary results suggest that BMPs do improve water quality, and that fish and invertebrates respond to agricultural management.