Skies will be mostly sunny and hot today with high temperatures reaching the mid and upper 90s, and overnight lows falling to the low 70s and upper 60s basinwide.
Lake Buchanan has a level of 1,017.90 feet above mean sea level (ft msl) this morning. The level of Lake Travis is 677.68 feet msl this morning. The surface temperature of Lake Travis near Mansfield Dam is 71° F. (See http://www.arlut.utexas.edu/omg/weather.html for additional information.)
In the Colorado River below the Highland Lakes, releases for irrigation in the coastal counties of Colorado, Wharton and Matagorda continue. Below Austin this morning, flows in the Colorado River are ranging from 900 to 1,375 cfs from Bastrop to Columbus, and further downstream flows are from 600 cfs to 325 cfs from Wharton to Bay City due to irrigation diversions.
Unscheduled releases could occur at any of the Highland Lakes dams without notice to maintain lake levels, pass flood flows, meet sudden demands for hydroelectric power, or for testing and maintenance of equipment. In the event of high energy demands in Texas, the Electric Reliability Council of Texas (ERCOT) may call upon LCRA for hydroelectric generation at anytime without notice. Lakeside residents and lake users immediately downstream of the dams should take necessary precautions against possible high flows and higher lake levels.
Elevations contained in this summary are based on LCRA "legacy" or NGVD 29 datum and are not adjusted to the newer NAVD 88 datum. FEMA and the National Flood Insurance Program reference the NAVD 88 datum in their floodplain maps and regulations. Lake levels reported by LCRA should not be used to determine first floor elevations of buildings for compliance with floodplain regulations. Surveyors should refer to http://harn.lcra.org/ for information about LCRA GPS control marks and benchmarks.
LCRA's state-approved Water Management Plan for the operation of the HighlandLakes includes requirements to provide water for river habitat and water quality along the lower river ("Instream Flow Requirements") and for the health and productivity of Matagorda Bay ("Bay and Estuary Requirements"). These requirements vary from either lower "critical" or higher "target" amounts according to the amount of water stored in the Highland Lakes at different times of year, and from month to month according to seasonal environmental needs. The lower river and Matagorda Bay may receive more water than required by the Water Management Plan because water is being delivered to downstream users or due to downstream inflows and storms.
Instream Flow Requirements: The minimum instream flow requirements are to maintain at least 46 cfs at the Austin river gauge at all times. When inflows to the HighlandLakes are sufficient, the requirements are to maintain at least target levels for mean daily flow at Austin, Bastrop, Columbus and Wharton, as shown in the table above.
Bay and Estuary Requirements: Based on the HighlandLakes storage on January 1, 2008, higher "target" amounts for Bay and Estuary monthly inflow volumes apply in 2008, when inflows to the Highland Lakes are sufficient. The Bay and Estuary monthly inflow goal for May is 162,200 acre-feet, and the May month-to-date inflow is 16,283 acre-feet.
