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E.V. Spence Reservoir: Implementing TMDLs for Total Dissolved Solids and Sulfate

A project to improve water quality by reducing total dissolved solids (TDS) and sulfate in E.V. Spence Reservoir. Together, the adopted TMDLs and the approved I-Plan are the road map to improved water quality.

photo of E.V. Spence Reservoir
E.V. Spence Reservoir

Counties: Coke, Mitchell, Nolan
Parameters: Total Dissolved Solids (TDS), Sulfate
River Basin: Colorado River
Segment: 1411

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Background and Goals

The E.V. Spence Reservoir is located in Coke County. With a surface area of 15,893 acres, it is an important source of water for more than 300,000 people in surrounding cities, including Big Spring, Odessa, Midland, and San Angelo. Additionally, the reservoir serves mining and industrial uses, and it is a popular destination for recreational fishermen. Water quality testing found that excessive levels of sulfate and total dissolved solids (salinity) are affecting the lake and its use for drinking water. The goal of this project is to reduce point and nonpoint sources of these pollutants to restore and maintain water quality standards for the reservoir.

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To reduce salinity concentrations, the Colorado River Municipal Water District (CRMWD) has been managing diversions of fresh water from the Colorado River into the reservoir since 2001. Prior to the drought of 2010–2011, the levels of saline contaminants were dropping in E.V. Spence Reservoir and the watershed of the Colorado below it. Then, due to persistent drought, water levels in the reservoir dropped drastically. This, in turn, led to concentration of chloride, sulfate, and TDS. As of 2018, chloride, sulfate, and TDS still exceed the criteria.

The Railroad Commission of Texas identified and plugged abandoned and orphaned oil wells to eliminate that source of pollution. As CRMWD finds new wells, they notify the Railroad Commission and work to plug them. The RRC also completed a study to evaluate other management practices that would reduce or prevent salinity in the streams that flow into the reservoir.

photo of the E.V. Spence Reservoir

Plugging a well in the
E.V. Spence Watershed

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Public Participation

A steering committee was formed in April 1999 to solicit advice, comments, and ideas from interested parties. Membership included a diverse cross-section of stakeholders in the upper Colorado River Basin, including representatives from industry, agriculture, petroleum operations, environmental groups, private citizens, and government agencies.

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The commission adopted these TMDLs on June 14, 2002.

The EPA approved these TMDLs on May 9, 2003, at which time they became part of the state's Water Quality Management Plan.

Updates to TMDLs

From time to time, it is necessary to revise TMDLs to account for changing conditions in the watershed, such as new or amended permits, or urban growth, or to correct oversights in the original TMDL report. Revisions to the load allocations in TMDLs are made via the state’s WQMP, which is updated quarterly.

The WQMP provides projected effluent limits for use in planning and permitting activities under the Texas Pollutant Discharge Elimination System (TPDES). The TCEQ reviews all applications for new and amended permits for conformance with applicable portions of the WQMP, including adopted TMDLs.

Revisions to the TMDL are documented in the approved WQMP updates listed below.

Learn more about the State's Water Quality Management Plan.

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The commission approved the I-Plan on August 10, 2001. 

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For More Information

Please email and mention the E.V. Spence Reservoir in the subject line. Or call us at 512-239-6682. 

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