Water Grand Challenges: Environmental Flows




Warren, Emily

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The purpose of environmental flows management is to establish a flow regime to support healthy ecosystems. In 2007, environmental flows were established in Texas through Article 1 of Senate Bill 3. This water allocation process attempts to address the trend of overallocation, maintaining healthy coastal estuaries and rivers in Texas, and how to protect water sources. Rivers must carry a certain amount of water in order to maintain healthy riparian systems and aquatic biota in its beds, banks, bays, and estuaries. In Texas, the over-allocation of surface water rights has necessitated legislation to define, quantify, and provide adequate environmental flows. In watershed basins with resources that are already over-allocated, permit cutbacks do not necessarily apply. The purpose of S.B 3 bill is to strike a balance between surface water extraction rights and healthy rivers and bays. The ability of river basin and bay systems in Texas to perform valuable functions for maintaining the health and well-being of wetland and riparian ecosystems depends on adequate freshwater flows. Additionally, with adequate flow, rivers, bays, and estuaries provide valuable ecological services in the form of aquifer recharge, storm surge buffers, and as natural waste treatment facilities for non-point source pollution. Rivers also provide surface water for agriculture, industry, energy production, and municipal and recreational users. Healthy bays contribute billions of dollars to the state economy through the fishing industry, wildlife protection, tourism, and recreation. Estuarine ecosystems support industries totaling a combined $3.5 billion per year (1994 dollars). This includes seafood, sport fishing, and recreational industries. Inadequate freshwater discharge into Texas’ bays leads to increased salinity, poor biological health, and economic loss.



water quality, ecosystems, environmental flows, water resources, watersheds


Warren, E. (2013). Water grand challenges: Environmental flows (Report No. 2013-20). Texas State University-San Marcos, San Marcos, Texas.


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