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Carancahua Bay

This is a project to reduce bacteria and protect recreational safety in Carancahua Bay. The stakeholders and TCEQ developed a total maximum daily load (TMDL) and implementation plan (I-Plan), which together are the road map for improving water quality. The TMDL was adopted and the I-Plan has been approved.
photo of carancahua bay
Carancahua Bay
Photo Courtesy of the Texas Institute for
Applied Environmental Research
map of the Carancahua Bay watershed

Counties: Calhoun, Jackson
Parameter: Bacteria
Basin: Bays and Estuaries
Segment: 2456
Assessment Unit (AU): 2456_02

On this page:

Background and Goals

Since 2006, high concentrations of bacteria, which are found in both human and animal waste, have been observed in the upper half of Carancahua Bay (Segment 2456). The presence of these bacteria may indicate a health risk to people who swim or wade in the bay—activities referred to as “contact recreation” in the Texas Surface Water Quality Standards. The goal of this project is to improve water quality in order to protect recreational uses.

In response to these conditions, stakeholders in the watershed worked with TCEQ to develop a TMDL and a plan to implement it. A TMDL is like a budget—it determines the amount (or load) of bacteria that a water body can receive and still support safe recreation. The allowable load is then allocated among categories of sources within the watershed. The I-Plan outlines the measures that will be used to reduce pollution.

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Description of Watershed

Carancahua Bay is located along the Texas Gulf Coast midway between the cities of Palacios and Port Lavaca. The bay is adjacent to the northern part of Matagorda Bay and includes parts of Calhoun and Jackson counties. Carancahua Bay drains 319 square miles, and its watershed includes parts of Calhoun, Jackson, Matagorda, and Wharton counties. Carancahua Bay has two assessment units (AUs). AU 2456_1 is the lower half of the bay, and AU 2456_02 is the upper half of the bay. Only AU 2456_02 is impaired due to bacteria.

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Get Involved

In all its TMDL projects, TCEQ gathers opinions and information from people who represent government, permitted facilities, agriculture, business, environmental, and community and private interests in the watershed.

Since 2016, staff from the Texas Water Resources Institute (TWRI) and TCEQ worked with communities, interest groups, and local organizations to distribute information about this project and involve stakeholders in developing the I-Plan. All public meetings about this project are open to anyone interested. Watch for meeting announcements here and on the TWRI website.

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Approved I-Plan

Community stakeholders worked together to create the I-Plan. The Commission approved the stakeholders' plan on August 26, 2020.

Status of Activities

TCEQ provides opportunities for stakeholders to report on progress and changes in the watershed. Tracking of implementation progress allows stakeholders to evaluate actions taken, identify actions that may not be working, and make any changes as necessary.

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Adopted TMDL

Community stakeholders worked with the TCEQ to develop the TMDL. On August 26, 2020, the Commission adopted the TMDL for bacteria in Carancahua Bay. EPA approved the TMDL on October 9, 2020, at which time it became part of the state's Water Quality Management Plan.

Revisions to TMDLs

From time to time, it is necessary to revise TMDLs to account for changing conditions in the watershed. Revisions to the load allocations in TMDLs are made via the state’s Water Quality Management Plan (WQMP).

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.


Updates are made to account for changing conditions in the watershed, such as new or revised wasteload allocations, permits that have been canceled or have expired, or changed facility names. Updates use the same units of measure as the original TMDL.

  • April 2021, Appendix II, page 16

WQMP updates may be viewed in person at the TCEQ Library, Building A, 12100 Park 35 Circle, Austin, Texas. Electronic versions of updates published from 2014 through present are available on the Texas State Library and Archives Commission website .

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Contact the TMDL Program

Please e-mail and mention Carancahua Bay in the subject line. Or call us at 512-239-6682.

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communities working together taking care of our rivers, lakes, and bays