Chocolate Bay
This is a project to reduce bacteria and protect recreational safety in the Chocolate Bay Watershed. The stakeholders and TCEQ have developed nine total maximum daily loads for waterbodies within the watershed and are developing an implementation plan, which together will be the road map for improving water quality.
County: Brazoria, Fort Bend, and Galveston
Parameter: Bacteria
River Basin: Bays and Estuaries, San Jacinto-Brazos Coastal
Segments: 1107, 1108, 2432A, 2432B, 2432C, 2432D, and 2432E
Assessment Unit(s): 1107_01, 1108_01, 2432A_01, 2432A_02, 2432A_03, 2432B_01, 2432C_01, 2432D_01, and 2432E_01
On this page:
- Background and Goals
- Watershed Description
- Get Involved
- Status and Activities
- Draft I-Plan
- Adopted TMDLs
- Reports
- Contact the TMDL Program
Background and Goals
Since 2010, high concentrations of bacteria, which are found in both human and animal waste, have been observed in the watershed. The presence of these bacteria may indicate a health risk to people who swim or wade in the water bodies—activities referred to as “contact recreation” in the Texas Surface Water Quality Standards.
The goal of this project is to reduce bacteria so the public can safely enjoy recreational activities in these waters. To achieve this, TCEQ and stakeholders have developed total maximum daily loads (TMDLs) for bacteria in these watersheds:
- Chocolate Bayou Watershed
- Mustang, Persimmon, and New Bayous Watershed
- Halls Bayou Tidal and Willow Bayous Watershed
Stakeholders are now developing a regional implementation plan (I-Plan) to reduce bacteria in those watersheds, all of which make up the larger watershed of Chocolate Bay.
Watershed Description
The Chocolate Bay watershed is approximately 313 square miles, mostly in eastern Brazoria County, with a portion in Fort Bend County. Three main tributaries flow southeast through the region: Chocolate Bayou, Mustang Bayou, and Halls Bayou. The main communities include: Algoa, Alvin, Arcola, Fresno, Hillcrest, Iowa Colony, Liverpool, Manvel, Missouri City, and Pearland. Some lie entirely within the watershed while others include only portions of their boundaries.
Get Involved
TCEQ seeks input from anyone who represents government, permitted facilities, agriculture, business, environmental, or community and private interests in the watershed.
See meeting records and find details for public meetings in the "Get Involved" section of the Houston–Galveston Area Council’s webpage for the San Jacinto-Brazos Coastal Basin Bacteria Reduction Project . Everyone is welcome to attend these public meetings.
Staff from the Houston–Galveston Area Council (H-GAC) have been working with stakeholders to distribute information about this project and involve them in developing the I-Plan for watershed improvement.
Status and Activities
Draft I-Plan
Stakeholders are currently drafting an I-Plan for this watershed.
Adopted TMDLs
The US Environmental Protection Agency (EPA) has approved all TMDLs, at which point they became an update to the state’s Water Quality Management Plan.
- Two TMDLs for Indicator Bacteria in Chocolate Bayou – The Commission adopted these TMDLs on May 22, 2024. EPA approved them on July 26, 2024
- Five TMDLs for Indicator Bacteria in the Mustang, Persimmon, and New Bayou Watersheds – The Commission adopted these TMDL on Aug. 6, 2025. EPA approved them on Oct. 20, 2025
- Two TMDLs for Indicator Bacteria in the Halls Bayou Tidal and Willow Bayou Watersheds – The Commission adopted these TMDLs on July 23, 2025. EPA approved them on Oct. 20, 2025
Reports
H-GAC staff completed technical reports for each watershed that compiled and analyzed all available bacteria data and considered sources of the bacteria and their relative contributions.
- Technical Support Document for Chocolate Bayou, May 2022
- Technical Support Document for Mustang, Persimmon and New Bayou Watersheds, January 2024
- Technical Support Document for Halls Bayou Tidal and Willow Bayou Watershed, January 2025
Contact the TMDL Program
Please e-mail tmdl@tceq.texas.gov and reference the Chocolate Bay TMDL in the subject line. Or call us at 512-239-6682.



