** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** ALTERNATIVE IRRIGATION WATER SOURCES ARE KEY TO MANAGING WATER SUPPLIES, BUT OFTEN CONTAIN GREATER SALT CONCENTRATIONS THAT MIGHT INCREASE FOOD SAFETY RISKS. THE SALINITY OF TRADITIONAL IRRIGATION WATERS IS RISING IN MANY LOCATIONS AND PRODUCERS ARE TURNING TO ALTERNATIVE IRRIGATION SOURCES, WHICH ALSO HAVE MODERATE SALINITY LEVELS. THIS IS TRUE FOR DRIER REGIONS LIKE CALIFORNIA AND ARIZONA, BUT ALSO IN MORE TEMPERATE CLIMATES LIKE VIRGINIA. FOR EXAMPLE, THE EASTERN SHORE OF VIRGINIA, IS A LARGE VEGETABLE PRODUCING REGION, WHERE VIRGINIA RANKS IN THE TOP TEN OF FRESH-MARKET TOMATO PRODUCTION IN THE US. PRODUCERS ON DELMARVA OFTEN CAPTURE RAINWATER AND HOLD IT IN RETENTION PONDS TO SUPPLEMENT OR REPLACE TRADITIONAL GROUNDWATER IRRIGATION. IRRIGATION WATER AND SOIL ARE RESERVOIRS OF BACTERIA THAT CAN CONTAMINATE VEGETABLE CROPS. AT LEAST FIVE SALMONELLOSIS OUTBREAKS HAVE BEEN LINKED TO DELMARVA SINCE 2002, WITH AT LEAST ONE OUTBREAK ASSOCIATED WITH USE OF CONTAMINATED IRRIGATION POND WATER. LIKEWISE, OUTBREAKS OF PATHOGENIC E. COLI HAVE BEEN TRACKED TO IRRIGATION CANALS IN PRODUCTION REGIONS WHERE THE SALINITY OF SOILS AND WATER TENDS TO BE HIGH. WHETHER OR NOT THE SALINITY DIRECTLY PLAYED A ROLE IN CREATING THESE ENVIRONMENTAL RESERVOIRS IS UNKNOWN.SALINITY CHANGES THE SURVIVAL OF FECAL INDICATOR BACTERIA AND PATHOGENS, AS WELL AS THE OVERALL COMMUNITY STRUCTURE OF MICROBIOTA PRESENT IN WATER AND SOILS. VERY HIGH SALT CONCENTRATIONS PRESERVES FOOD BECAUSE IT KILLSPATHOGENS. HOWEVER, THE EFFECTS OF SMALL INCREASES IN SALINITY ON PATHOGEN PERSISTENCE IN WATER AND SOIL AT THE FIELD END OF THE FARM-TO-FORK CONTINUUM HAVE NOT BEEN TESTED. RECENT WORK BY OUR TEAM SHOWS SMALL INCREASES IN SALINITY AND SPECIFIC SALT TYPES CAN ACTUALLY INCREASE THE PERSISTENCE OF FECAL INDICATOR BACTERIA IN WATER. NON-PATHOGENIC E. COLI IS THE CURRENT FECAL INDICATOR BACTERIA FOR AGRICULTURAL WATER UNDER THE NEW FOOD SAFETY MODERNIZATION ACT'S PRODUCE SAFETY RULE. IF SALINITY ALSO INCREASES PATHOGEN PERSISTENCE, THE USE OF ALTERNATIVE IRRIGATION WATER SOURCES WITH HIGHER SALINITIES, SUCH AS BRACKISH, RETURN FLOW, OR RECYCLED WATERS, OR SALINIZATION OF TRADITIONAL SOURCES, MAY INCREASES RISKS TO FOOD SAFETY.THE RESEARCH OBJECTIVE OF THIS PROPOSED WORK IS TO DETERMINE HOW SALINITY AND SALT TYPE IN ALTERNATIVE IRRIGATION WATER ALTERS THE FATE OF FIB AND FOODBORNE PATHOGENS IN FOOD PRODUCTION. BASED ON PRELIMINARY DATA, THE CENTRAL HYPOTHESIS IS THAT MODERATE SALINITY LEVELS (0.35 - 1.0 DS M-1 INCREASE THE PERSISTENCE AND CONCENTRATION OF FIB AND FOODBORNE PATHOGENS IN WATER, SOIL, AND PLANT FRUITS AND LEAVES, BUT THE MAGNITUDE OF THE EFFECTS DEPENDS ON SALT TYPE. THE RATIONALE IS THIS WORK WILL PROVIDE: 1) KNOWLEDGE NECESSARY TO DETERMINE WHETHER ALTERNATIVE IRRIGATION SOURCES INCREASE THE PERSISTENCE OF FIB AND FOODBORNE PATHOGENS, AND RISK OF CONTAMINATION; AND 2) INFORMED RECOMMENDATIONS FOR ALTERNATIVE AND SALINIZING IRRIGATION WATERS, WHICH WILL ULTIMATELY IMPROVE MANAGEMENT OF ALTERNATIVE WATER SOURCES IN VEGETABLE PRODUCTION. WE WILL TEST THE CENTRAL HYPOTHESIS BYCOLLECTINGIRRIGATION WATER SAMPLES FROM SOURCES IN VIRGINIA, MEASURE THE IN-SITU CONCENTRATIONS OF FIB AND THE WATER CHEMISTRY, AND IN THE GREENHOUSE,INOCULATINGAND MEASURE THE PERSISTENCE OF SALMONELLA, E. COLI O157:H7, AND FIB IN WATER, SOIL AND PLANTMESOCOSMS WITH DIFFERING SALINITIES AND SALT TYPES.THROUGH OUR PROJECT ACTIVITIES WE WILL DEVELOP RECOMMENDATIONS TO MITIGATE POTENTIAL FOOD SAFETY RISKS FROM PATHOGEN CONTAMINATION OF VEGETABLES VIA IRRIGATION WATERS BY IDENTIFYING SALINITY RANGES AND TYPES OF IRRIGATION WATERS THAT ARE SAFE, AND THOSE THAT REQUIRE ADDITIONAL MANAGEMENT. THIS APPLICATION SUPPORTS THEGOAL OF PROVIDING SCIENCE-BASED, CREDIBLE AND RELIABLE BENCHMARKS FOR NONTRADITIONAL WATER USED TO IRRIGATE FOOD CROPS, BY ADDRESSING RISKS OF BIOLOGICAL CONTAMINATION DUE TO SALINIZATION. BROADLY, WE WILL HELP US AGRICULTURE MAINTAIN FOOD SAFETY AND HUMAN HEALTH WHILE REDUCING THE FRESHWATER DEMAND FOR IRRIGATION BY SUBSTITUTING THE USE OF NONTRADITIONAL WATER SOURCES.