Technical Abstract: There is increasing private and public interest in whether the investment in conservation practice installation has been a worthy use of public funding. As part of the 2002 Farm Bill, the USDA spends around $4 billion annually on the following conservation programs: Environmental Quality Incentive Program (EQIP), Conservation Reserve Program (CRP), Conservation Security Program (CSP), Wetland Reserve Program (WRP), Wildlife Habitat Incentives Program (WHIP), and the Grassland Reserve Program (GRP). The Conservation Effects Assessment Project (CEAP) was initiated in 2003 as a joint effort between the USDA Agricultural Research Service (ARS) and the Natural Resources Conservation Service (NRCS) to quantify the benefits of applied conservation practices over the history of federal soil stewardship programs. CEAP has two components: National Assessment, and Watershed Assessment. The National Assessment will use a modeling approach to estimate the benefits of conservation practices for all watersheds of the US. The Watershed Assessment will rely on case studies from ARS Benchmark Watersheds, NRCS Special Emphasis Watersheds, and CSREES Special Grants Watersheds to provide in-depth water quality data bases for the National Assessment. The Yalobusha River Watershed (YRW) in Mississippi is one of 12 ARS Benchmark Watersheds in the Watershed Assessment CEAP effort. One of the main objectives for the YRW is to use historical data to quantify the benefits of the past applied conservation practices both environmentally and economically. This report documents data compiled by the Mississippi State University Extension Service as part of a Sub-contract Agreement (SCA) with the United States Department of Agriculture-ARS National Sedimentation Laboratory (NSL). Data collection included conservation practices established by the Natural Resource Conservation Service (NRCS), Farm Service Agency (FSA), Army Corp of Engineers (COE), and stream data from the United States Geological Survey (USGS). Conservation practice data includes: CRP, EQIP, WHIP, and COE grade control structures. A preliminary report for the smaller Topashaw Canal (TC) Watershed within the YRW is included in Appendix 5. This work found that 42% of the sediment yield in the TC watershed is from gully erosion. The most common conservation practice in the TC watershed to control gully erosion is to install grade stabilization structures. NRCS data suggest that these structures should reduce the annual sediment yield from 11.5 T/ha/yr to 0.1 T/ha/yr. However, measurements have not been made to determine the accuracy of these sediment reduction estimates. Quantification of the sediment reduction, both at the field and watershed scales, is the main focus of the watershed assessment component of this CEAP study which will be accomplished experimentally through monitoring of ephemeral gullies with and without drop-pipe structures, surveying of undisturbed gullies, along with monitoring of upstream and downstream sediment loads. However, this document strictly reports the compilation of historical data and not an analysis of these data. The landuse, conservation practices, soil distribution, and stream flow data compiled in this report will enable watershed modeling to determine how effective the CPs established since 1985 have been in reducing sediment yield.