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Mission and Aransas Rivers, Tidal Portions: A Community Project to Protect Recreational Uses

A community project to keep recreation safe in tidal segments of the Mission and Aransas rivers by reducing bacteria levels. The stakeholders and TCEQ are developing total maximum daily loads (TMDLs) and an implementation plan (I-Plan), which together will provide the road map for improving water quality.
scenic photo of Copano Bay from shore
Aransas River Tidal
Photo by Texas AgriLife

Watershed Counties: Aransas, Bee, Goliad, Karnes, Refugio, and San Patricio
Parameter: Bacteria
Basin: San Antonio-Nueces Coastal
Segments: 2001, 2003

Background and Goals

High concentrations of bacteria are often found in the tidal portions of the Mission and Aransas Rivers. High concentrations of bacteria may indicate a health risk to people who swim or wade in the rivers—activities called “contact recreation” in the state’s standards for water quality.

Bacteria are commonly found in the intestines of warm-blooded organisms such as humans, livestock, cats, and dogs. These bacteria in water may indicate the presence of disease-causing microorganisms.

The goal of the project is to reduce bacteria levels to protect people who swim or wade in the rivers. The Texas Water Resources Institute (TWRI) Exit the TCEQ is coordinating development of the TMDLs and I-Plan.

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Draft TMDLs and Implementation Plan

Updated Information The TCEQ requests comments from the public on both the draft TMDLs and the Implementation Plan for the tidal segments of the Mission and Aransas Rivers.

Public Meeting

The TCEQ will hold a meeting to provide the public with an opportunity to comment on the draft TMDLs and draft implementation plan.

November 5, 2015,
6:00 p.m.
Refugio Community Center
305 Swift Street
Refugio 78377

At this meeting, individuals have the opportunity to present oral statements when called upon in order of registration. An agency staff member will give a brief presentation at the start of the meeting and will be available to answer questions before and after all public comments have been received.

Persons with disabilities who have special communication or other accommodation needs who are planning to attend the meeting should contact the TCEQ at (512) 239-6682. Requests should be made as far in advance as possible.

Written Comments

Comments may be submitted in writing by mail, fax, or online. Written comments must be submitted to the TCEQ no later than midnight on November 23, 2015.

Comments should reference either the Two Total Maximum Daily Loads for Indicator Bacteria in the Tidal Segments of the Mission and Aransas Rivers: Segment Numbers 2001  and 2003 or the Implementation Plan for Two Total Maximum Daily Loads for Indicator Bacteria in the Tidal Segments of the Mission and Aransas Rivers: Segments Number 2001 and 2003. Please be specific about whether you are commenting on the draft TMDLs or the draft Implementation Plan.

Submit Comments by Mail

Address your comments to:

Roger Miranda
Water Quality Planning Division
Texas Commission on Environmental Quality
MC 203
P. O. Box 13087
Austin, Texas, 78711-3087

Submit Comments by Fax

Attention: Roger Miranda
(512) 239-1414

Submit Comments Online

Comment online at our eComments Web page. In the "Your Comments" section, select the report on which you wish to comment from the drop-down menu.

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Project History

The state and its partners collected and analyzed extensive amounts of data about the project watersheds from 2004 through 2010. While the TCEQ, the Texas State Soil and Water Conservation Board (TSSWCB), and stakeholders in the watershed evaluated the most appropriate strategy for reducing bacteria concentrations, agricultural producers voluntarily participated in educational activities aimed at better understanding the water quality issues and various methods for reducing the amount of bacteria that can wash off agricultural property and into waterways.

In 2011, stakeholders and the state agencies decided to develop TMDLs and an implementation plan for the tidal portions of the Mission and Aransas Rivers in the Copano Bay watershed. The goal of a TMDL is to determine the amount (or load) of a pollutant that a body of water can receive and still support its designated uses. The allowable load is then allocated among the categories of sources within the watershed. Stakeholders work with the state to develop an implementation plan (I-Plan) with measures that reduce pollutant loads. 

Copano Bay, which is identified as having an impaired oyster waters use, was considered in the assessment stage of this project. Designation of the oyster waters impairment is based on a risk assessment by the Department of State Health Services (DSHS). These risk assessments are not based on concentrations of bacteria in the water; rather, they are based on certain risk factors such as the likelihood of high rainfall and runoff or the influx of sewage from failing or inefficient domestic treatment systems.

Concentrations of bacteria in the waters of the bay are within acceptable levels. Consequently, development of a bacteria TMDL for Copano Bay is not necessary, and would not be effective in reducing the risk assessed by the DSHS.

Get Involved

Project staff are informing the public about this project through a series of public meetings. The meetings are open to everyone.

In all its projects, the TCEQ seeks to gather opinion and information from people who represent government, permitted facilities, agriculture, business, environmental, and community and private interests in the watershed. The TWRI Exit the TCEQ is coordinating public participation in development of the TMDLs and the I-Plan.

Educational Resources

See the Texas Water Resources Institute website for the Copano Bay Water Quality Education Project Exit the TCEQ, which provides information about educational programs and demonstrations for land and livestock owners. These programs and demonstrations are designed to increase awareness of water quality issues and best management practices for reducing bacteria in stormwater runoff.

Meeting Summaries and Presentations

Meeting summaries and presentations are in PDF Adobe Acrobat PDF Document.

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Project Reports

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For More Information

Please e-mail us at, and mention the Mission and Aransas Rivers project in the subject. Or call us at 512-239-6682. You may contact the TWRI project manager, Allen Berthold, at 979-845-2028 or

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