2006 Annual Report 4d.Progress report. This report serves to document research conducted under a Specific Cooperative Agreement between the ARS-Hydrology and Remote Sensing Laboratory and University of Maryland Horn Point Environmental Laboratory in Cambridge, Maryland. Additional details of research can be found in the report for the parent project 1265-12130-002-00D entitled, "ASSESSING CLIMATE, SOIL AND LANDSCAPE PROCESSES AFFECTING AGRICULTURAL ECOSYSTEMS. To assess impact of agricultural Best Management Practices (BMPs) on water quality, monthly base-flow samples of stream water exiting from 15 subwatersheds within the Tuckahoe Creek sub-basin of the Choptank watershed. These water samples were been analyzed for nutrient and pesticide content with data compiled. Select storm flow events have also been sampled and analyzed for water quality. The depth of water in each stream have been continuously monitored and data logged and development of rating curves for each stream is in progress based on water flux measurements at different stages of stream. A series of significant storm events during the year have provided good opportunity to establish rating curves for eight of the subwatersheds by use of an Acoustic Stream Channel Profiler. This effort to gauge streams will continue into FY 2007. In coordination with the stream base flow sampling, water samples were collected in the main channel of the Choptank River at 5 transect locations. These data collection efforts will provide validation data for the AnnAGNPS and SWAT water quality models.