Print PageIn 2007, the Texas Legislature passed Senate Bill 3 which established a stakeholder-driven process to determine environmental flow standards for the major river basin and bay systems of Texas. To date, seven of 11 river basins have begun or completed the process to develop instream flow and freshwater inflow recommendations. Because Senate Bill 3 was designed to be an accelerated, consensus-based process executed at the basin-level, the expert science teams for each basin had only one year to develop flow recommendations. As such, each expert science team developed distinct approaches to determining flow recommendations, particularly with respect to determining freshwater inflow needs for the estuaries. This presentation will provide an overview of the freshwater inflow methodologies and recommendations developed by four basin-bay expert science teams to determine inflow needs for five estuarine systems: Sabine Lake, Galveston Bay, Matagorda Bay, San Antonio Bay, and Copano and Aransas bays.
Results/Conclusions
While the science teams were tasked with using the best available science to determine flow recommendations, all groups, with one exception, elected to develop new approaches rather than rely on existing studies and recommendations. The approaches range from (1) simply accepting the recommended instream flows for the lowermost portions of contributing rivers as being sufficient for the estuary to (2) conducting various salinity suitability or salinity-zonation analyses in order to identify inflows necessary to provide desirable salinity conditions for select focal species to (3) developing drought inflow criteria to ensure survival of key species during periods of low freshwater inflow. While these approaches have limitations, they offer a means for rapidly assessing freshwater inflow needs using relatively little data and thus contribute to the set of tools available for this field of study. Additional elements of this presentation will be to discuss how the new freshwater inflow recommendations compare to existing state recommendations for the estuaries and how the basin-bay stakeholder committees have modified the science team’s freshwater inflow recommendations to meet the needs for human uses of water. Finally, because the goal of this process is to develop new environmental flow standards, closing statements will address how the State’s water permitting and regulatory agency ultimately translated this information into environmental flow standards upon which future water permits in Texas are to be based.
