** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THIS ENVIRONMENTAL AND NATURAL RESOURCE ECONOMICS PROPOSAL ADDRESSES NUTRIENT POLLUTION FROM AGRICULTURE, THE IMPACT OF POLLUTION ON THE VALUE OF ECOSYSTEM SERVICES, METRICS TO MEASURE THOSE IMPACTS NATIONWIDE, AND MAKES SIGNIFICANT ADVANCES IN INTEGRATING ECOLOGICAL AND ENVIRONMENTAL SCIENCE MODELS AND METHODS. THIS TEAM OF ECONOMISTS, AGRICULTURAL ENGINEERS, AND WATER QUALITY MODELERS WILL DEVELOP A NATIONAL INTEGRATED ASSESSMENT MODEL (IAM) TO MEASURE THE SOCIAL COSTS OF NUTRIENT POLLUTION ACROSS THE UNITED STATES. THE NEW MODEL, HYDROECON, COMBINES ECONOMIC MODULES OF WATER RESOURCES WITH A NATIONAL SOIL WATER AND ASSESSMENT+ (SWAT+) HYDROLOGICAL MODEL, THE NATIONAL AGROECOSYSTEMS MODEL (NAM). KEY ECONOMIC CONSIDERATIONS INCLUDE IMPACTS ON HOUSING, WATER-BASED RECREATIONAL USE, DRINKING WATER TREATMENT, HUMAN HEALTH, CLIMATE CHANGE, AND NON-USE VALUES. THE PROJECT WILL USE HYDROECON TO ESTIMATE THE SPATIALLY-EXPLICIT AND AGGREGATE NATIONAL DAMAGES FROM NUTRIENT POLLUTION AND CORRESPONDING NET BENEFITS OF USDA'S MAIN CONSERVATION PROGRAMS SUCH AS THE CONSERVATION RESERVE PROGRAM AND ENVIRONMENTAL QUALITY INCENTIVES PROGRAM. THE PROJECT WILL ALSO USE HYDROECON TO ANALYZE HOW NET BENEFITS OF WATER QUALITY IMPROVEMENTS VARY BASED ON SOCIOECONOMIC FACTORS SUCH AS INCOME, RACE, AND THE RURAL/URBAN DIVIDE. THIS STUDY WILL INCORPORATE ANTICIPATED CHANGES IN CLIMATE TO UNDERSTAND HOW CLIMATE CHANGE WILL IMPACT THE OVERALL NET BENEFITS OF USDA'S CONSERVATION PROGRAMS AND THE DISTRIBUTION CONSEQUENCES OF SUCH CHANGES. A WEB-BASED PLATFORM WILL DISPLAY KEY METRICS ON THE SPATIALLY-EXPLICIT COSTS AND BENEFITS OF USDA PROGRAMS BY COUNTY AND BY WATERSHED ACROSS THE CONTINENTAL UNITED STATES.