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Colorado River Below E.V. Spence Reservoir: Implementing Total Maximum Daily Loads (TMDLs)

As part of implementing the total maximum daily loads (TMDLs) adopted by the Commision for this Colorado River segment, the Railroad Commission evaluated data from two sites, Ballinger and Wendkirk, to design, and determine where to locate, recovery systems that will reduce saline groundwater flows to the Colorado River.


In 2000, the Colorado River below E.V. Spence Reservoir (Segment 1426 of the river) was not meeting the criteria in the water quality standards for total dissolved solids (TDS), sulfates, and chloride. The segment flows from Robert Lee Dam south-easterly through Coke and Runnels Counties, ending about two miles downstream from where Mustang Creek joins the river.

In 2007, TCEQ adopted two TMDLs that identified the amount by which pollutant loadings should be reduced and allocated the reductions to the pollutant source categories in the watershed. The stakeholders then developed an implementation plan (I-Plan) for the TMDLs with the leadership of the Upper Colorado River Authority. The I-Plan identified several measures to improve water quality, including reducing saline groundwater sources related to oil production and the number of salt cedar trees in the watershed.

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Project Description

In this project, the Railroad Commission comprehensively evaluated the lithology, groundwater flow conditions, and both surface and groundwater quality at the Ballinger and Wendkirk sites. They then used this information to complete a feasibility study for a recovery system for saline groundwater between oil field seeps and the Colorado River and determine the optimum location for it. Modeling was used to predict recovery rates of the installation. The effectiveness of the installed systems was determined by sampling groundwater monitoring wells and surface water. The Railroad Commission previously eliminated many possible sources of salinity in the watershed by plugging orphaned or abandoned wells that can leak brine, which is a by-product of oil production.

As a result of implementing this project, along with several other measures stakeholders put in place, the Colorado River Below E.V. Spence segment is now meeting the criteria in the Texas Surface Water Quality Standards. The segment was removed from TCEQ's index of all impaired waters in the 2020 Texas Integrated Report of Surface Water Quality. The TMDLs remain in effect.

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For More Information

To find out more about the NPS Program, call 512-239-6682 or e-mail us at

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