**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** SOIL AND WATER SALINITY ARE PERVASIVE GLOBAL CHALLENGES THAT INCREASINGLY IMPACT THE VIABILITY OF AGRICULTURAL PRODUCTION AND RURAL COMMUNITIES. ELEVATED SALINITY NEGATIVELY AFFECTS CROP YIELDS, REDUCES AGRICULTURAL PROFITS, AND DEGRADES AGRICULTURAL LAND VALUES. THE GOAL OF THIS PROJECT IS TO DEVELOP A BETTER UNDERSTANDING OF THE TRADE-OFFS ASSOCIATED WITH SPATIALLY-EXPLICIT IRRIGATION MANAGEMENT POLICIES THAT CAN REDUCE THE COSTS OF SALINITY-RELATED EXTERNALITIES. THE PROJECT TEAM WILL ACHIEVE THIS OBJECTIVE BY ESTIMATING THE EFFECT OF SALINITY ON LAND USE AND IRRIGATION DECISIONS USING HISTORICAL DATA AND DEVELOPING AN INTEGRATED HYDRO-SALINITY-ECONOMIC MODEL THAT ITERATIVELY COMBINES A HYDROLOGIC MODEL THAT ACCOUNTS FOR SALT FATE AND TRANSPORT IN AN IRRIGATED STREAM-AQUIFER SYSTEM, AND AN ECONOMIC MODEL THAT GENERATES PREDICTIONS OF AGRICULTURAL PRODUCER BEHAVIOR. THE HYDRO-SALINITY-ECONOMIC MODEL WILL BE APPLIED TO AN AGRICULTURAL REGION IN THE LOWER ARKANSAS RIVER BASIN OF COLORADO TO STUDY THE TRADE-OFFS AMONG DIFFERENT WATER MANAGEMENT POLICIES THAT ARE DESIGNED TO REDUCE THE COSTS OF SALINITY. WE PLAN TO ANALYZE BOTH PRICE AND QUOTA-BASED POLICIES, WITH THE SPECIFIC POLICY DETAILS DETERMINED THROUGH DISCUSSIONS WITH STAKEHOLDERS IN THE REGION. WE WILL ALSO DISSEMINATE THE MODELING RESULTS DIRECTLY TO LOCAL STAKEHOLDERS AND MAKE THE MODELING FRAMEWORK PUBLICLY AVAILABLE SO THAT IT CAN BE UTILIZED BY RESEARCHERS AND POLICY MAKERS IN OTHER CONTEXTS. THE PROPOSED PROJECT FALLS WITHIN THE ENVIRONMENTAL AND NATURAL RESOURCE ECONOMICS PROGRAM AREA, CODE A1651. OUR PROPOSAL CONSIDERS THE INTERACTIONS BETWEEN AGRICULTURE, NATURAL RESOURCE CONSERVATION, AND THE ENVIRONMENT. IT ALSO CONSIDERS THE INCENTIVE MECHANISMS AND POLICIES THAT PROMOTE RESOURCE CONSERVATION AND SUSTAINABILITY.