The State of the Protection of Freshwater Inflow to the Bays and Estuaries of Texas




Wassenich, Tom

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Freshwater inflow to the bays and estuaries of Texas is considered essential to maintain their biological productivity. The reduced salinity of the estuaries is necessary for the juvenile stage of many marine species. More than 90 percent of fish harvested along the coast are dependent on estuaries for some part of their life cycle. Anthropogenic changes such as diversions and reservoirs increasingly affect the quantity and timing of freshwater entering the bays and estuaries. The protection of freshwater inflows in Texas is a complex process with many components. Lawmakers, citizens, water planners, water administrators and commissioners of state agencies need a better understanding of all aspects of this complex subject. A thorough examination of the current state of protection will facilitate an analysis of the effectiveness of protection of the state's estuaries. This document examines the major components of protection at the state and federal levels including laws, agencies, water rights, water plans, and bay and estuary studies, both from an administrative and a quantitative perspective. From this analysis it is possible to determine the amount, if any, of freshwater inflow that is protected by the system. The system of protection is fragmented and not well–defined. Three state agencies share partial responsibilities for inflow protection with no real central authority. Rivers are managed with little emphasis on estuaries, water rights are granted without well–defined freshwater inflow protection formulas, and water plans are made using different protection criteria than those used for appropriations of water or the bay and estuary studies. The water planning and appropriation areas are dominated by the water users with little input from conservationists and others concerned about adequate inflows for healthy bays and estuaries. Currently the state does not have a complete set of tools to deal with all of the aspects of inflow protection even were there a will to do so. This document recommends several specific research projects to improve the system of protection: • Comparative examination of the water planning criteria with the recommended flows of the bay and estuary studies. • Analysis of the amount of freshwater inflows protected since the 1985 requirements for protection were instigated. • Determination of the effects of reservoir management on freshwater inflow timing. • Review of the Water Availability Model and its assumptions related to groundwater and pre–anthropogenic flows. • Analysis of the effects of maximum permitted and proposed water use on estuarine productivity repeated with every five year planning cycle. • Establishment of a minimum freshwater inflow protection system that applies to low–flow situations while protecting the productivity of the estuaries. The original document covered the period through the end of the 2003 Legislature. Updates for 2004 and 2005 were added to analyze and comment on the Scientific Advisory Committee's Report to the 2005 Texas Legislature, which began its session in January 2005. The 2005 update also covers the 2005 Legislature and special sessions that were unsuccessful in implementing new environmental flow legislation. It is hoped that this document will provide a platform for continuing scrutiny of the freshwater inflow protection system in Texas, leading to ongoing positive adaptive management of sustainable environmental flows for the bays and estuaries.


Issued as "A Guide to the Protection of Freshwater Inflow in Texas" by River Systems Institute at Texas State University. (See Related Files).


inflow, freshwater, Texas, environmental protection, bays, estuaries


Wassenich, T. (2004). The state of the protection of freshwater inflow to the bays and estuaries of Texas (Unpublished masters thesis). Texas State University-San Marcos, San Marcos, Texas.


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