AQUARIUS: A Computer Program for Water Quality Closure Rule Evaluation and Shellfish Sanitation Simulation

The United States shellfish industry is regulated under the National Shellfish Sanitation Program; administered federally by the U.S Food and Drug Administration, and at the state level by departments of health or agriculture. Shellfish authorities are empowered to close shellfish harvest if water quality drops below food safety levels. Because monitoring for all human pathogens in growing areas is not feasible, fecal coliform bacteria are used as indicator organisms for the potential presence of pathogens from fecal contamination. Every decade, sanitary surveys are conducted during adverse pollution conditions to establish equations and rules for conditionally approved growing areas to predict rainfall levels when fecal coliform levels might exceed the “NSSP 14/43” safety standard. Modifying these rules requires an extensive sampling programs and analyses. As watersheds change, there is pressure to reclassify growing sites and to modify closure rules. The AQUARIUS program is the first tool developed to directly evaluate closure rules for the shellfish industry, and to perform a series of “what-if” scenarios for selected variables. AQUARIUS uses the rainfall data to simulate the open/close status of a given growing site for any length of time under two closure rules: one the current rule and the other proposed new rule. AQUARIUS then uses the fecal coliform data from the site to calculate the “NSSP 14/43” standards for three situations: “site open under current rule”, “site open under new rule”, and “site open during critical period”. AQUARIUS then runs a series of T-Tests statistical procedures to compare the fecal coliform level of “site open under current rule” versus “site open under new rule”; and to compare the fecal coliform level of “Site open under current rule” versus “site open during critical period”. Based on the results of SSP 14/43” standards and T-Tests, the new closure rule is either accepted or rejected.