Weekend River Report

Skies over the Colorado River basin on Friday night will become partly to mostly cloudy. Low temperatures will be in the 30s to 40 degrees, with southeast to northeast winds 5 to10 mph.  On Saturday skies will be mostly cloudy.  High temperatures will be in the upper 50s and low 60s with southeast to northeast winds 5 to 10 mph.  There is a slight rain chance in coastal regions.  Saturday night will be cloudy with a 20 percent chance of rain and low temperatures in the 40s and 50s, and south to southeast winds 5 to 10 mph.  Sunday will be cloudy with a 20-30 percent chance of rain. High temperatures will be in the 60s and lower 70s with south to southeast winds 10 to 15 mph.  On Sunday night and Monday look for mostly to partly cloudy skies with a 20-30 percent chance of showers. Lows will be in the 40s west, 50s central, to the 60s in coastal regions.  High temperatures will be in the 60s and lower 70s. 

Above the Highland Lakes, streamflow in the Colorado River and major tributaries remains minimal, and many small streams have no flow.  To learn how the ongoing drought is affecting our region please see http://www.lcra.org/water/drought/index.html.  Minimal flow conditions will restrict floating and fishing this weekend.

Lake Buchanan is about 6.3 feet below its historic average for November. The level of Lake Travis is about 11.9 feet below the historic November average. The water temperature at the surface of Lake Travis is about 69 degrees.

Minimal releases will be made from Lake Buchanan into Lakes Inks, LBJ and Marble Falls to maintain lake levels, and further downstream to help meet municipal and industrial demands. Minimal releases from Lake Travis will pass through Lake Austin and Lady Bird Lake and on to the Colorado River below Austin to supply water for industrial demands and to meet environmental flow requirements.

Flow in the Colorado River below Austin is minimal because of lower releases from the Highland Lakes and lack of rainfall.  River flow between Bastrop and Columbus ranges from about 150 to 350 cfs, and flow between Wharton and Bay City ranges from about 300 cfs to 500 cfs.  Flow between Wharton and Bay City remains slightly elevated due to local heavy rainfall from earlier this week.  Please see the Weekly Fishing Report on the Texas Parks and Wildlife Department web site to find out what is biting and where.

For up-to-date basin conditions please go to http://hydromet.lcra.org/.

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 Highland Lakes 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 Highland Lakes 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 Highland Lakes 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 November is 44,400 acre-feet and the month-to-date inflow is 21,061 acre-feet.