On April 11, LCRA began releasing water from the Highland Lakes to meet the environmental needs of the blue sucker. The large river fish is considered a threatened species by the Texas Parks and Wildlife Department, and LCRA is required to meet certain flow levels during the blue suckers' spawning season. If the flow of the river below the Highland Lakes is not enough to meet the requirements, LCRA will release water from the lakes to make up the deficit.
According to the state-approved Water Management Plan for lakes Travis and Buchanan, LCRA must maintain flows at or above 500 cfs from Bastrop to Eagle Lake for a continuous period of not less than six weeks during the months of March, April and May to meet the blue sucker's requirements. LCRA will stop releasing water to meet those flow requirements after midnight tonight, May 24.
Streamflow Conditions above the Highland Lakes
Rainfall shifted from the upper Hill Country to the Pedernales River basin and directly over Lake's Travis and Austin. Rainfall was wide spread and ranged from 1 to 4.5 inches for this area. The Colorado River near San Saba is flowing at 59 cfs. Above Lake LBJ the Llano River at Llano is flowing at 39 cfs while Sandy Creek near Kingsland is flowing at 18 cfs. Above Lake Travis the Pedernales River near Johnson City is flowing at 40 cfs.
As of 8:45 am, the level of Lake Buchanan is 990.67 ft msl which is about 22.9 feet below its historic May average of 1,013.58 ft msl. The level of Lake Travis is 628.23 ft msl which is about 42.8 feet below its historic May average of 671.07 ft msl. The total combined storage in the Highland Lakes two water storage reservoirs, Buchanan and Travis, is at 784,000 acre-feet, or 39 percent of capacity. The surface water temperature of Lake Travis as measured near Mansfield Dam is 75 degrees.
Lake levels reported by LCRA are not referenced to the NAVD 88 datum, and should not be used to determine first floor elevation of buildings for compliance with floodplain regulations. Surveyors should refer to: http://harn.lcra.org/website/harn/ for information about LCRA GPS control marks and benchmarks.
As noted above, LCRA must maintain flows in the Colorado River at or above 500 cfs from Bastrop to Eagle Lake for a continuous period of not less than six weeks during the months of March, April and May to meet environmental requirements for the blue sucker. LCRA will be releasing water as needed to meet those flow requirements from April 11 to the last week in May. To maintain a continuous flow with as little water from the Highland Lakes as possible, LCRA is using floodgates to control the release of water from Tom Miller and Mansfield dams, and is coordinating with Austin Energy to control operations at Longhorn Dam, which is owned by the City of Austin. LCRA appreciates the cooperation of the City of Austin and Austin Energy in conserving water during the spring environmental releases.
Lakes Buchanan and Travis are the two water storage lakes in the Highland Lakes system, and supply water for more than 1 million people. Water is released from Lake Travis through Mansfield and Tom Miller dams for cities, power plants, farming, environmental flow requirements and other uses along Lake Austin and the lower Colorado River below Lake Austin. Water is released from Lake Buchanan through Buchanan, Inks, Wirtz and Starcke dams to replace a portion of the water taken from lakes Inks, LBJ and Marble Falls for cities, evaporation and other uses, and to replace a portion of the water that is released from Lake Travis. In addition, dam operations may occur at any of the dams at any time as needed to pass localized inflows to the lakes or for hydroelectric generation. Water is usually released through the dams by hydroelectric generation. However, releases may also be made through floodgates or spillways.
Streamflow Conditions Below the Highland Lakes
Downstream from the Highland Lakes this morning, the Colorado River at Bastrop is flowing at 575 cubic feet per second (cfs) while the Colorado River at Columbus is flowing at 540 cfs. Further downstream, the flow at the Colorado River at Wharton is at 145 cfs.
Colorado River Environmental Flow Requirements in 2013
On January 1, 2013 the combined storage of lakes Buchanan and Travis was below 1.1 million acre-feet. Environmental flow requirements for Instream Flow and Matagorda Bay and Estuary Freshwater Inflow Needs are set to maintain "critical" levels in 2013, in accordance with the Water Management Plan.
"Critical" levels for Instream Flow are to maintain an instantaneous flow of at least 46 cfs in the Colorado River at Austin at all times, and maintain a mean daily flow of at least 120 cfs in the Colorado River from Bastrop to Eagle Lake on all days.
"Critical" levels for Matagorda Bay and Estuary Freshwater Inflow Needs are to maintain a monthly inflow volume of at least 14,260 acre-feet in the Colorado River at Bay City in all months, subject to the availability of inflows to the Highland Lakes in excess of senior water rights.
Flow in the Colorado River may be greater than the environmental flow requirements at times, because water is being delivered to downstream users, or because of storm runoff from rainfall over the lower basin.
Highland Lakes Releases for Agricultural Irrigation in 2013
Most farmers in the lower Colorado River basin are going without irrigation water from the Highland Lakes for the second year in a row.
This historic cutoff of Highland Lakes water became official at 11:59 p.m. on March 1, when the combined storage of lakes Travis and Buchanan was less than 850,000 acre-feet. That is the trigger point in an emergency drought relief order requested by LCRA and approved by the Texas Commission on Environmental Quality on February 13. Combined storage at 11:59 p.m. was 822,782 acre-feet, or 40.9 percent full.
With the emergency relief, farmers in the Gulf Coast and Lakeside irrigation divisions will not receive any water from the Highland Lakes this year. Farmers in the Garwood Irrigation Division are entitled to about 20,000 acre-feet of Highland Lakes water this year based on the purchase agreement of the Garwood water right.
For up to date weather forecasts (including a 7-day forecast) for your area go to: http://www.srh.noaa.gov/ewx/ and enter your Zip Code in the Local Forecast bar located in the upper left hand corner.
Matagorda Bay and Estuary Freshwater Inflow Needs In a critical year, Matagorda Bay inflow needs from the Colorado River are 14,260 acre feet per month, equivalent to a continuous flow of about 240 cubic feet per second (cfs) on average. Freshwater Inflows to Matagorda Bay are measured at the USGS Bay City Gauge. This gauge is affected by the tide, particularly at low flow rates. The reported flow measurements at the Bay City gauge are provisional, and subject to revision by the USGS. The reported monthly inflow volumes, measured at the Bay City gauge, are displayed below: