Implementation of a Freshwater Inflow Recommendation for the Trinity-San Jacinto Estuary (Galveston Bay)




Loeffler, Cindy

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Texas Natural Resource Conservation Commission


Freshwater inflows (FWI) from rivers, streams, and local runoff maintain the salinity gradients, nutrient loadings, and sediment inputs that in combination produce an ecologically sound and healthy estuary. This report summarizes TPWD studies of the FWI needed to maintain the unique biological communities and ecosystems characteristic of a healthy Trinity-San Jacinto Estuary. Methods for determination of the quantity and quality of freshwater inflows needed to maintain our coastal margins have been developed by the State Bays and Estuaries Research Program [consisting of the Texas Water Development Board (TWDB) and Texas Parks and Wildlife Department (TPWD) as mandated by the Texas Water Code. In this report, the effectiveness of different computed inflow regimes (MinQ and MaxH) predicted by optimization modeling are critically evaluated. This analysis uses fisheries survey results from the TPWD Coastal Fisheries Resource Monitoring Database to validate the computer simulations. Observed abundances of estuarine fishery species are empirically evaluated against FWI regimes proposed from the theoretical models. Comparison of modeling results with observed fisheries survey data results in a FWI recommendation that will realistically maintain the biological health and productivity of the Trinity - San Jacinto Estuary. The Texas Parks and Wildlife Department, along with the Texas Water Development Board and the Texas Natural Resource Conservation Commission, continues to promote efforts to implement freshwater inflow needs, most notably through participation in the Galveston Bay Freshwater Inflows Group and Senate Bill 1 Regional Water Planning.


pg. 103


freshwater inflows