Texas Water Development Board

To provide leadership, planning, financial asistance, information, and education for the conservation and responsible development of Water for Texas.
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RESERVOIR VOLUMETRIC SURVEYS
History and overview of the TWDB's Lake Volumetric Survey Program. Lake surveys completed by the TWDB since 1993. Products provided by the Volumetric Survey Program.
Surveying methods and technology used for lake volumetric surveys. Volumetric survey rate schedule and Section 22 funding. List of priority reservoirs most in need of a new survey.
Persons to contact for getting a reservoir surveyed.

History and Overview

In 1991, the Texas Legislature authorized the Texas Water Development Board to develop a non-profit, self-supporting, reservoir (lake) volumetric survey program to provide a quick, accurate, and affordable surveying method to determine current reservoir storage capacities. Thus TWDB began performing Hydrographic Surveys. Storage volumes for many Texas reservoirs were originally obtained by analyzing available topographic maps, and many reservoirs have not been resurveyed in the decades since their construction, some since before the 1950's. Because sediment deposition constantly reduces reservoir volumes over time, and because the original reservoir volumes were limited by the accuracy of existing topographic maps, estimates of the current capacities for un-surveyed reservoirs are subject to error. With population and statewide water use increasing, water shortages are a real possibility in places where storage capacities are significantly less than what is assumed.

Since 1993, the Surface Water Section (now the Hydrographic Survey Team) of the TWDB has completed surveys of approximately 100 reservoirs. Fifty-two of the 77 major water-supply reservoirs in the state have been surveyed by TWDB. A list of priority reservoirs has been compiled based on the reservoir's use and on the date the reservoir was last surveyed.

A standard volumetric survey report is generated typically within three months of the completion of the field survey. Included in the report are updated elevation-area-capacity tables, bathymetric contour maps, and survey cross-sections. Sample products obtained from the Board's 1997 survey for Lake Tawakoni are available on-line for viewing.

The program utilizes the latest satellite surveying technology (GPS), differential global positioning system (DGPS) and acoustic depth sounder for data-collection, and geographic information system (GIS) software for data-processing.

Many interested parties in the past were unable to afford reservoir surveys due to the high cost of traditional methods. With the use of newer and more efficient methods, survey costs are now significantly lower than in the past. In addition, assistance is available through the U. S. Army Corps of Engineers [Planning Assistance to States (Section 22)] to qualifying reservoir owners. Survey charges vary according to the surface area of the lake and other considerations.

Updated elevation-area-capacity tables and other products generated by the Board's survey program are used by engineering firms and planners to determine reservoir yield, by TWDB and USGS in reporting statewide reservoir contents, and by TNRCC as part of their permitting requirements.


For more information contact:
Gayla Ray
Telephone (512) 936-0817


Last Modified: 7/16/2004
Texas Water Development Board (TWDB) - All Rights Reserved