AN IMPORTANT BARRIER LIMITING FRESHWATER PROVISIONING IN AGRICULTURAL WATERSHEDS IS THE INABILITY TO ACCESS PRIVATELY HELD DATA NEEDED TO IDENTIFY AND TARGET CRITICAL SOURCE AREAS OF NUTRIENT RUNOFF. TO OVERCOME THIS BARRIER, WE WILL ADDRESS TWO KNOWLEDGE GAPS: 1) HOW CAN PUBLIC-PRIVATE PARTNERSHIPS (PPPS) BE FORMED TO TARGET BEST MANAGEMENT PRACTICES (BMPS) TO AGRICULTURAL FIELDS THAT DISPROPORTIONATELY DEGRADE WATER QUALITY, AND 2) WHAT GAINS IN WATER QUALITY CAN BE ACHIEVED BY TARGETING THESE FIELDS? THESE KNOWLEDGE GAPS ARE IMPORTANT GLOBALLY, AND PARTICULARLY RELEVANT IN THE WESTERN LAKE ERIE BASIN WHERE MORE THAN 5% OF CROPLAND HAS GREATER THAN 2.5 TIMES THE MAXIMUM RECOMMENDED AGRONOMIC LEVEL OF SOIL PHOSPHORUS (P). THESE "LEGACY P" FIELDS CAN LEACH NUTRIENTS AT AN ELEVATED RATE TO DOWNSTREAM ECOSYSTEMS FOR DECADES, AND, GLOBALLY, HAVE BEEN IDENTIFIED AS A MAJOR CONTRIBUTOR TO NUTRIENT RUNOFF AND IMPACTS SUCH AS HARMFUL ALGAL BLOOMS AND EUTROPHICATION. AS SUCH, THEY RESTRICT THE AVAILABILITY OF QUALITY WATER RESOURCES SUPPORTING AGRICULTURAL, INDUSTRIAL, MUNICIPAL AND RECREATIONAL USES. WE WILL DEVELOP AN INITIAL PPP TO TARGET BMPS TO LEGACY P FIELDS AND SUPPORT THE EXPANSION OF THIS APPROACH WITH: 1) SOCIO-ECONOMIC ANALYSES TO DEVELOP EXPANSION PROTOCOLS, 2) WATERSHED MODELING TO PROJECT LARGE-SCALE IMPACTS, AND 3) AN EXTENSION PROGRAM TO BUILD KNOWLEDGE AND SUPPORT. LEVERAGING PREVIOUSLY UNAVAILABLE PRIVATE DATA TO TARGET INTERVENTION MAKES THE LARGEST GAINS IN WATER QUALITY POSSIBLE WHILE INCREASING THE QUANTITY OF AVAILABLE WATER. THE PROGRAM AREA PRIORITY ADDRESSED IS "TARGETED ACTIVITIES TO OVERCOME BARRIERS, SO THAT MORE SUSTAINABLE MANAGEMENT PRACTICES ARE ADOPTED."