Using Aerial Photography to Measure Impacts of In-stream and Riparian Area Conservation BMPs

There is growing interest in evaluating the impact of agricultural conservation best management practices (BMPs) under real world conditions at the watershed scale. As part of a Conservation Effects Assessment Program (CEAP) watershed project, our team sought to evaluate retrospectively the impacts of a conservation program from the 1990s on a range of water quality conditions. We found that traditional methods of water quality monitoring (grab samples of stream water taken periodically throughout the year) created a data record that was limited in geographic and spatial detail and that likely missed important short-term surges in nutrient loadings and water quality conditions. To compensate for the weaknesses of direct measurements of water quality, we explored the use of indirect alternative indicators of conservation BMP impacts. This presentation reports on our use of matched aerial 3-band videography taken in 1992 and 2007 to evaluate the long-run impacts of best management practices on the condition of streams and riparian areas in the Little Bear watershed. The analysis compares changes conditions between \u27treatment\u27 stream segments that received BMPs against \u27control\u27 segments that did not receive project BMPs. Results suggest some types of BMPs had measurable positive impacts on riparian conditions. The strengths and weaknesses of this method for evaluating the effects of conservation practices will be discussed