** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** NITRATE CONTAMINATION IN STREAMS, LAKES, AND ESTUARIES IS A CRITICAL PROBLEM IN MANY AGRICULTURAL WATERSHEDS. WATER QUALITY DATA AVAILABILITY IS CRITICAL IN MONITORING STREAM HEALTH AND MAKING MANAGEMENT DECISIONS. IN THE US, THE ENVIRONMENTAL PROTECTION AGENCY (EPA) AND US GEOLOGICAL SURVEY (USGS) ALONG WITH STATE AGENCIES MONITOR WATER QUALITY AND QUANTITY. WATER QUALITY MONITORING, ESPECIALLY NITRATE DATA IS TYPICALLY AT COARSE TEMPORAL RESOLUTION. WITH THE CONTINUED ADVANCEMENT OF IN-STREAM NITRATE SENSOR TECHNOLOGY, USGS AND SEVERAL STATE AGENCIES ARE COLLECTING HIGH-FREQUENCY (15- TO 60-MINUTE INTERVALS) NITRATE DATA USING OPTICAL SENSORS OVER THE LAST DECADE. OUR TEAM WILL DEVELOP AN INTEGRATED (FIELD DATA COLLECTION, BIOPHYSICAL, AND MACHINE LEARNING) MODELING FRAMEWORK FOR UNDERSTANDING THE NITRATE DYNAMICS OF A REGION AND GENERATE SPATIALLY AND TEMPORALLY CONTINUOUS DAILY NITRATE CONCENTRATION DATA, WHICH COULD BE USED FOR EVALUATING ECOSYSTEM HEALTH AND DESIGNING MORE EFFECTIVE AND TARGETED WATERSHED MANAGEMENT STRATEGIES.