AS DIRECTED BY FOOD SAFETY MODERNIZATION ACT (FSMA) OF 2011, THE FDA PROPOSED A SET OF STANDARDS WITH SPECIFIC PROCEDURES AND GUIDELINES FOR SAFE GROWING, HARVESTING, PACKING, AND STORAGE OF FRESH PRODUCE INTENDED FOR DIRECT HUMAN CONSUMPTION, TO MINIMIZE THE RISKS OF ADVERSE HEALTH EFFECTS. THE STANDARDS INCLUDE REGULATIONS PERTAINING TO MICROBIAL QUALITY OF IRRIGATION WATER THAT CAN COME IN CONTACT WITH PRODUCE AND REQUIRES PERIODIC TESTING OF IRRIGATION WATER QUALITY. THE PROPOSED RULE USES GENERIC E. COLI (ESCHERICHIA COLI) AS THE INDICATOR MICROORGANISM TO ASSESS POTENTIAL MICROBIAL CONTAMINATION OF IRRIGATION WATER. MANY SURFACE IRRIGATION WATER SOURCES IN WESTERN US REGULARLY EXCEED PROPOSED GENERIC E. COLI LIMITS (DADOLY AND MICHIE, 2010). HOWEVER, THE REVISED RULE (FDA, 2014) RECOGNIZES MICROBIAL DIE-OFF POST LAST IRRIGATION, AND DIRECTS TO EITHER DELAY HARVEST OR INCREASE STORAGE LENGTH TO ASSURE MICROBIAL DIE-OFF IF WATER QUALITY TESTS ARE POSITIVE. A PROBABILISTIC ANALYSISOF TRADEOFFS BETWEEN COSTS OF NEW MICROBIAL WATER QUALITY RULES AND BENEFITS FROM IMPROVED SAFETY OF FRESH FRUITS AND VEGETABLES INTENDED FOR DIRECT HUMAN CONSUMPTION WITHOUT PROCESSING IS NEEDED. IN THIS PROJECT WE PROPOSE TO EXAMINE THE ECONOMIC EFFICIENCY OF MICROBIAL IRRIGATION WATER QUALITY RULES IN TERMS OF ACHIEVING DESIRED FOOD SAFETY IMPROVEMENT AT LOWEST COST TO CONSUMERS AND PRODUCERS. ECONOMIC MODELING AND MICROBIOLOGIC FIELD EXPERIMENTS ARE PROPOSED TO BE USED IN COMBINATION TO GENERATE INSIGHTS ABOUT STOCHASTIC PERFORMANCE OF MICROBIAL IRRIGATION WATER QUALITY STANDARDS AND TESTING REQUIREMENTS.