River Operations Report - Water Supply Operations

Summary

This River Report provides information about current river operations and conditions of the Colorado River and the Highland Lakes related to water supply operations.

When conditions warrant, the LCRA River Operations Control Center posts information about flood operations on the Flood Summary Report.

You can navigate to specific sections of the River Report using the links below:

Data presented on this web page includes provisional data obtained by LCRA for the use of its professional staff. This data is retrieved and displayed automatically, and is subject to revision.

Current Operations and Conditions
Last Update: 9/20/2014 8:36 AM

The remnant center of what used to be Hurricane Odile produced scattered rain showers and isolated thunderstorms mainly in the Hill Country yesterday.  Some of these storms produced very intense rainfall and some impressive 24-hour totals, but the rains did not translate into any significant stream flow above the Highland Lakes.

In the lower river, the runoff from the Thursday rain event continues to make its way towards the Bay.  The National Weather Service is periodically issuing updates to the forecasts for the Colorado River at Bastrop and the other downstream locations. You can see the NWS forecasts here: http://floodstatus.lcra.org/#rlevels.

Saturday’s weather includes a 40 percent chance for additional rain showers and thunderstorms with locally heavy rain possible. Unscheduled releases from the Highland Lakes dams may occur suddenly and unexpectedly due to emergency hydroelectric generation or other reasons. Residents should exercise caution and avoid being in the water near the dams.

Releases from Lake Buchanan will be made as needed through Buchanan, Inks, Wirtz and Starcke dams to replace a portion of the water taken by cities, power plants, evaporation and other uses along lakes Inks, LBJ and Marble Falls, and to replace a portion of the water that is released from Lake Travis.

Releases from Lake Travis will be made as needed to supply water to customers along Lake Austin, such as the City of Austin and the West Travis County Public Utility Agency, and to replace water that is released or evaporated from Lake Austin.

Releases from Lake Austin will be made as needed to and supplement the natural flow of the Colorado River below Lake Austin in supplying water for customers downstream of the Highland Lakes and to replace water that is evaporated from Lady Bird Lake or lost in conveyance along the lower river.

In addition to passing through releases from upstream dams, water may be released from lakes Inks, LBJ, Marble Falls and Austin through Inks, Wirtz, Starcke, and Tom Miller dams, respectively, to pass through runoff from localized storms and inflows from tributary creeks and streams, as needed, to control the level of these lakes.

 



Current Lake Levels
Lake (Dam)Date/Time of Last ReportLake Level
(ft msl)
7 Days Ago
(ft msl)
30 Days Ago
(ft msl)
Buchanan (Buchanan)9/20/2014 4:45 PM 986.60 986.83988.42
Inks (Inks)9/20/2014 4:45 PM 887.04 887.10887.30
LBJ (Wirtz)9/20/2014 4:45 PM 824.47 824.69824.69
Marble Falls (Starcke)9/20/2014 4:45 PM 736.46 736.45736.44
Travis (Mansfield)9/20/2014 4:45 PM 624.87 622.94625.52
Austin (Miller)9/20/2014 4:45 PM 492.59 492.04492.08


Highland Lakes Profile Click to view dynamic Highland Lakes System Profile
Click to view webpage.


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9/20/2014 8:00 AM
Short term lake level forecasts for Buchanan and Travis:

Tomorrow: Buchanan = 986.6 ft msl, Travis = 625.0 ft msl
One week: Buchanan = 986.4 ft msl, Travis = 624.6 ft msl



Current Storage In Lakes Buchanan and Travis
LakeDate/Time
of Last Report
Lake Level


(ft msl)
Historical
September
Average
(ft msl)
Difference
From
Average
(ft)
Storage
When Full

(Ac-Ft)
Current
Storage

(Ac-Ft)
Current
Percent
Full
%
Difference
From Full

(Ac-Ft)
Buchanan 9/20/2014 4:45 PM986.601,009.8823.3 875,588 309,144 35 % 566,444
Travis 9/20/2014 4:45 PM624.87663.1938.3 1,134,956 394,205 35 % 740,752
Total Combined Storage in Lakes Buchanan and Travis 2,010,544703,34935%1,307,196




Upstream Flow Conditions and Gauged Inflows
LocationDate/Time
of Last Report
Current Flow


(cfs)
Previous Day
Average Flow

(cfs)
Inflow Runoff
Factor
Previous Day
Adjusted
Average Flow
(cfs)
Previous Day
Gauged Inflow
Volume
(Ac-Ft)
Colorado River near San Saba 9/20/2014 4:55 PM 48.3 761.035 79 156
Llano River at Llano 9/20/2014 4:58 PM 222.5 1581.000 158 314
Sandy Creek near Kingsland 9/20/2014 4:58 PM 5.3 182.367 43 86
Pedernales River near Johnson City 9/20/2014 4:57 PM 341.9 1972.030 399 792
Previous Day Total Gauged Inflows*    6791,348

Inflows to the Highland Lakes are measured at four streamflow gauges shown in the table above. A runoff factor is applied to the measured flow to account for additional inflows that may occur downstream of each gauge. When the natural flow of the Colorado River upstream of the Highland Lakes is abundant, LCRA stores the excess water in the Highland Lakes, and lake levels rise.


Downstream Flow Conditions
LocationDate/Time
of Last Report
Current Flow

(cfs)
Previous Day
Average Flow
(cfs)
Previous Day
Flow Volume
(Ac-Ft)
Colorado River at Austin 9/20/2014 4:58 PM 166 8341,653
Colorado River at Bastrop 9/20/2014 4:57 PM 3,621 7,09314,069
Colorado River at Smithville 9/20/2014 4:41 PM 6,442 3,4476,837
Colorado River above La Grange 9/20/2014 4:57 PM 7,937 8211,628
Colorado River at Columbus 9/20/2014 4:55 PM 843 1,0642,111
Colorado River near Altair 9/20/2014 4:55 PM 1,022 6781,344
Colorado River at Wharton 9/20/2014 4:56 PM 523 324642
Colorado River near Lane City 9/20/2014 4:55 PM 498 357709
Colorado River at Bay City 9/20/2014 4:55 PM 680 6381,266

Note: The U.S. Geological Survey's (USGS) Bay City Gauge is strongly affected by tides from the Gulf of Mexico and provisional gauge readings may be inaccurate when flow in the river at Bay City is low, below about 2,000 cfs.  Provisional data is subject to revision by the USGS.




Previous Day Releases
Lake (dam)Approximate
Time of Release
Average
Discharge
(cfs)
Discharge
Volume
(Ac-Ft)
Buchanan (Buchanan)9/19: 2-5 pm310615
Inks (Inks)9/19: 2-5 pm389772
LBJ (Wirtz)9/19: 3-6 pm490972
Marble Falls (Starcke)9/19: Midnight-1 am; 3-4 am; 4-6 pm6051,200
Travis (Mansfield)9/19: No releases00
Austin (Miller)9/19: 5-11 am336666

The schedule for today’s hydroelectric generation is competitive electric market information, and is not available to the public. Water may be discharged suddenly and unexpectedly due to emergency hydroelectric generation or other reasons. Residents should exercise caution and avoid being in the water near the dams.

(Releases from Lady Bird Lake through Longhorn Dam are controlled by Austin Energy, the electric utility for the City of Austin.)



Instream Flow Conditions and Environmental Criteria
LocationCriteria
for Minimum
Flow
(cfs)
Previous Day
Minimum
Flow
(cfs)
Criteria
for Average
Flow
(cfs)
Previous Day
Average Flow

(cfs)
Colorado River at Austin 46198 834
Colorado River at Bastrop  4321207,093
Colorado River at Columbus  7391201,064

On Jan. 1, 2014, the combined storage of lakes Buchanan and Travis was 764,341 acre-feet. In accordance with the Water Management Plan, because storage was less than 1.4 million acre-feet, environmental flow requirements for instream flow are set to critical levels in 2014.

Critical instream flow levels are a minimum flow of at least 46 cubic feet per second (cfs) in the Colorado River at Austin, and an average flow of at least 120 cfs in the Colorado River from Bastrop to Eagle Lake, upstream of Wharton.




Freshwater Inflows to Matagorda Bay
MonthMonthly Inflow*
(Ac-Ft)
Monthly Criteria
(Ac-Ft)
January 36,865 14,260
February 23,816 14,260
March 45,960 14,260
April 18,694 14,260
May 186,259 14,260
June 59,721 14,260
July 19,303 14,260
August 8,353 14,260
September 14,260
October 14,260
November 14,260
December 14,260
Annual Total398,971171,120

The data in the table above shows monthly freshwater inflow volumes for 2014.On Jan. 1, 2014, the combined storage of lakes Buchanan and Travis was 764,341 acre-feet. In accordance with the Water Management Plan, because storage was less than 1.1 million acre-feet, environmental flow requirements for Matagorda Bay's freshwater inflow needs are set to critical levels in 2014. At critical levels, the Water Management Plan requires LCRA to maintain monthly inflows of at least 14,260 acre-feet in the Colorado River at Bay City in all months. This requirement is subject to the availability of inflows to the Highland Lakes in excess of senior water rights.

Freshwater inflows to Matagorda Bay are measured at the U.S. Geological Survey's (USGS) Bay City gauge. However, this gauge is strongly affected by tides from the Gulf of Mexico and provisional gauge readings may be inaccurate when flow in the river at Bay City is low, below about 2,000 cfs. Provisional data is subject to revision by the USGS. At these low river flows, LCRA uses data from the Lane City gauge to determine the amount of freshwater flowing into the bay. The Lane City gauge is upstream of the Bay City gauge and is not influenced by tide. When determining freshwater inflows to the bay using the Lane City gauge, LCRA subtracts the water diverted from the river downstream of the Lane City gauge but upstream of the Bay City gauge. The monthly inflow volumes at the Bay City gauge, as determined by LCRA, are displayed above.




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