| (a) For new water right authorizations which increase
the amount of water authorized to be stored, taken, or diverted as
described in §298.10 of this title (relating to Applicability),
the determination of the hydrologic condition for a particular season
shall be determined once per season. The conditions present on the
last day of the month of the preceding season will determine the hydrologic
condition for the following season. For each measurement point specified
in this section, either cumulative streamflow for the previous 12
months, combined storage in major reservoirs, or reservoir elevation
will determine the hydrologic condition, as described in subsections
(b) - (d) of this section.
(b) For measurement points located on the Colorado
River above Lake Travis and tributaries of the Colorado River, and
in the Colorado-Lavaca and the Lavaca-Guadalupe Coastal Basins, cumulative
streamflow for the preceding 12 months and the corresponding hydrologic
conditions are:
Attached Graphic
(c) For measurement points located on the Colorado
River below Lake Travis, the combined reservoir storage in Lakes Travis
and Buchanan and the corresponding hydrologic conditions are:
Attached Graphic
(d) For measurement points located in the Lavaca River
Basin, the reservoir elevation of Lake Texana and the corresponding
hydrologic conditions are:
Attached Graphic
(e) For purposes of water availability determinations,
for measurement points on the Colorado River above Lake Travis and
tributaries of the Colorado River, and in the Lavaca River Basin and
the Colorado-Lavaca and Lavaca-Guadalupe Coastal Basins, hydrologic
conditions used in the commission's water availability models shall
be calculated such that severe conditions occur approximately 5% of
the time, dry conditions occur approximately 20% of the time, average
conditions occur approximately 50% of the time, and wet conditions
occur approximately 25% of the time.
(f) For purposes of water availability determinations,
for measurement points on the Colorado River below Lake Travis, hydrologic
conditions used in the commission's water availability models shall
be calculated such that severe conditions occur approximately 5% of
the time, dry conditions occur approximately 45% of the time, and
average conditions occur approximately 50% of the time.
(g) The hydrologic condition indicators set out in
subsections (b) - (d) of this section govern the operations of permits
subject to this subchapter during the initial period, of not longer
than ten years, until the environmental flow standards in this subchapter
are reevaluated. Those indicators were calculated to achieve compliance
with the percentages of time stated in subsections (e) and (f) of
this section. The hydrologic condition indicators set out in subsections
(b) - (d) of this section will be recalculated, no less frequently
than once every ten years, in order to achieve, to the greatest extent
possible, compliance with the percentages of time stated in subsections
(e) and (f) of this section.
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