Texas Administrative Code › Title 30 - ENVIRONMENTAL QUALITY › Part 1 - TEXAS COMMISSION ON ENVIRONMENTAL QUALITY › Chapter 298 - ENVIRONMENTAL FLOW STANDARDS FOR SURFACE WATER › Subchapter B - TRINITY AND SAN JACINTO RIVERS, AND GALVESTON BAY › Section 298.220 - Schedule of Flow Quantities

Current through Reg. 49, No. 28; July 12, 2024
(a)
				  The environmental flow standards adopted by this subchapter constitute a
				  schedule of flow quantities made up of subsistence flow, base flow, and one
				  level of high flow pulses. Environmental flow standards are established at six
				  separate measurement locations in §
										298.225
				  of this title (relating to Environmental Flow Standards).
(b) Subsistence flow. The applicable
				  subsistence flow standard varies depending on the seasons as described in
				  §
										298.205 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 unless the
				  flow at the measurement point is above the applicable subsistence flow standard
				  for that point. If the flow at the measurement point is above the subsistence
				  flow standard but below the applicable 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
				  standard varies depending on the seasons as described in §
										298.205 of
				  this title. 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 is subject to a base flow standard. 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 that point is above the applicable base flow
				  standard, and below the applicable high flow pulse trigger level, 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 measurement point
				  does not fall below the applicable base flow standard.
(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.
(1)
				  Two pulses per season are to be passed (i.e., no storage or diversion by an
				  applicable water right holder) if the flows are above the applicable base flow
				  standard, and if the applicable high flow pulse trigger level is met at the
				  measurement point. The water right holder shall not divert or store water
				  except during times that streamflow at the applicable measurement point exceeds
				  the applicable high flow pulse trigger level and until either the applicable
				  volume amount has passed the measurement point or the applicable duration time
				  has passed since the high flowpulse trigger level occurred.
(2) If the applicable high flow pulse trigger
				  level does not occur in a season, then the water right holder need not stop
				  storing or diverting water to produce a high flow pulse. The water right holder
				  is not required to store water to be released later to produce a high flow
				  pulse.
(3) With the exception of
				  summer and fall, which are treated as a single season for purposes of pulse
				  flow compliance, each season is independent of the preceding and subsequent
				  seasons with respect to high flow pulse frequency.