Texas Administrative Code
Title 30 - ENVIRONMENTAL QUALITY
Part 1 - TEXAS COMMISSION ON ENVIRONMENTAL QUALITY
Chapter 298 - ENVIRONMENTAL FLOW STANDARDS FOR SURFACE WATER
Subchapter D - COLORADO AND LAVACA RIVERS, AND MATAGORDA AND LAVACA BAYS
Section 298.325 - Schedule of Flow Quantities
Current through Reg. 50, No. 13; March 28, 2025
(a) Schedule of flow quantities. The environmental flow standards adopted by this subchapter constitute a schedule of flow quantities made up of subsistence flow, base flow, and high flow pulses. Environmental flow standards are established at 21 separate measurement locations in § 298.330 of this title (relating to Environmental Flow Standards).
(b) Subsistence flow. The applicable subsistence flow standard varies depending on the seasons as described in § 298.305 of this title (relating to Definitions). For a water right holder to which an environmental flow standard applies, at a measurement point that applies to the water right, the water right holder may not store or divert water under severe hydrologic conditions, unless the flow at the measurement point is above the applicable subsistence flow standard for that point. During severe hydrologic conditions, if the flow at the measurement point is above the subsistence flow standard but below the applicable dry condition base flow standard, then the water right holder may divert or store water according to its permit, subject to senior and superior water rights, as long as the flow at the measurement point does not fall below the applicable subsistence flow standard.
(c) Base flow. The applicable base flow level varies depending on the seasons as described in § 298.305 of this title and the hydrologic condition described in § 298.320 of this title (relating to Calculation of Hydrologic Conditions). For a water right holder to which an environmental flow standard applies, at a measurement point that applies to the water right, the water right holder is subject to the base flow standard for the hydrologic condition prevailing at that time. For all measurement points except those on the Colorado River below Lake Travis, the water right will be subject to one of the following: a dry, an average, or a wet base flow standard. For all measurement points on the Colorado River below Lake Travis, the water right will be subject to either a dry or an average base flow standard. For all measurement points, the dry base flow standard applies during severe hydrologic conditions. For a water right holder to which an environmental flow standard applies, at a measurement point that applies to the water right, when the flow at the applicable measurement point is above the applicable base flow standard, but below any applicable high flow pulse levels, the water right holder may store or divert water according to its permit, subject to senior and superior water rights, as long as the flow at the applicable measurement point does not fall below the applicable base flow standard for that hydrologic condition.
(d) High flow pulses. High flow pulses are relatively short-duration, high flows within the watercourse that occur during or immediately following a storm event.
(e) Stored water. A water right owner that has stored water in accordance with the terms and conditions of its water right, including any applicable environmental flow requirement in effect at the time the water was stored, may divert, release, or use this water, even if the applicable environmental flow requirement is not met at the time of the subsequent diversion, release, or use of that stored water.
