Today will be mostly sunny with high temperatures in the upper 80s. However, winds from the south will begin to bring more cloudcover and higher humidity tonight and through the weekend. To learn how the drought is affecting our region please see http://www.lcra.org/water/drought/index.html.
Above the Highland Lakes this morning, streamflow in the Colorado River and tributaries remains minimal. LakeBuchanan is about 4 feet below its historic average for October. The level of LakeTravis is about 11.1 feet below the historic October average. The water temperature at the surface of LakeTravis is about 78 degrees.
Releases from LakeBuchanan today will pass into LakesInks, LBJ and MarbleFalls to maintain lake levels, and further downstream to help meet municipal, industrial and agricultural demands. Releases from LakeTravis will pass through LakeAustin and LadyBirdLake and on to the Colorado River below Austin to supply water for agricultural and industrial needs.
Flow in the Colorado River below Austin is variable with a strong current. River flow between Bastrop and Columbus ranges from 840 to 1,240 cfs, and flow between Wharton and Bay City ranges from 570 cfs to 515 cfs due to agricultural diversions.
Unscheduled releases could occur at any of the HighlandLakes 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 October is 47,400 acre-feet and the month-to-date inflow is 6,593 acre-feet.
