Mustang, Persimmon, and New Bayou Watersheds
Photo Courtesy of the
Houston-Galveston Area Council
Counties: Brazoria, Fort Bend
Parameter: Bacteria
Basins: Bays and Estuaries, San Jacinto-Brazos Coastal
Segments: 2432B, 2432C
Assessment Units (AUs): 2432A_01, 2432A_02, 2432D_01, 2432E_01
On this page:
- Background and Goal
- Watershed Description
- Get Involved
- Approved I-Plan
- Adopted TMDLs
- Reports
- Contact Us
Background and Goal
High concentrations of certain fecal bacteria have been identified in Mustang, Persimmon, and New Bayou Watersheds since 2010. Fecal bacteria are found in both human and animal waste. The presence of these bacteria may indicate a health risk to people who swim or wade in the bayous—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. Toward that goal, TCEQ and stakeholders have developed total maximum daily loads (TMDLs) for bacteria in the bayous. Stakeholders have also developed a regional Implementation Plan (I-Plan) to reduce bacteria in the Mustang, Persimmon, and New Bayou watersheds, the Chocolate Bayou watershed, and the Halls Bayou Tidal and Willow Bayou watersheds, which collectively form the larger Chocolate Bay watershed.
Watershed Description
The Mustang Bayou watershed is home to agricultural, residential, and commercial uses. Most of the residential development is in the upper half of the watershed. Agricultural production is an important economic base for most of the watershed, primarily rice and hay cultivation and cattle grazing. Chemical production facilities are clustered in the lowest area of the watershed, mostly between New Bayou and Chocolate Bayou, near Chocolate Bay.
Mustang Bayou, Segment 2432A, is approximately 43 miles long and flows southeast, beginning in Fort Bend County and continuing through Brazoria County. Its headwaters are within the city limits of Missouri City, although most of the stream is within the boundaries of Brazoria County. Mustang Bayou has been heavily modified and channelized along most of its length. It flows into New Bayou about 5 miles upstream of Chocolate Bay. The Mustang Bayou watershed, which includes Persimmon Bayou and New Bayou, is home to agricultural, residential, and commercial uses. Agricultural production is an important economic base for most of the watershed.
Persimmon Bayou, Segment 2432D, branches off from Mustang Bayou near the intersection of FM 2004 and CR 2917. The bayou flows southeastward for approximately 5 miles until it joins New Bayou near Chocolate Bay. New Bayou, Segment 2432E, flows southeastward about 16 miles and empties into Chocolate Bay.
Get Involved
Staff from the Houston–Galveston Area Council (H-GAC) have been working with communities, interest groups, and local organizations to distribute information about this project and involve stakeholders in watershed improvement activities. All public meetings about this project are open to anyone interested. Watch for meeting announcements here. See meeting records in the "Get Involved" section of the H-GAC's webpage San Jacinto-Brazos Coastal Basin Bacteria Reduction Project .
Chocolate Bay stakeholder meeting
The watershed stakeholder group will discuss any work done in relation to the Chocolate Bay Implementation Plan. During this meeting, we will discuss measures the community is taking to reduce fecal sources of bacteria to help Chocolate Bay meet water quality standards.- https://www.tceq.texas.gov/waterquality/tmdl/nav/chocolate-bay-stakeholder-meeting
- Chocolate Bay stakeholder meeting
- 2026-08-26T16:30:00-05:00
- 2026-08-26T18:30:00-05:00
- The watershed stakeholder group will discuss any work done in relation to the Chocolate Bay Implementation Plan. During this meeting, we will discuss measures the community is taking to reduce fecal sources of bacteria to help Chocolate Bay meet water quality standards.
Wednesday, Aug. 26, 2026
4:30 – 06:30 p.m.
Approved I-Plan
Community stakeholders worked together to create the Chocolate Bay I-Plan. The Commission approved the stakeholders' plan on August 12, 2026.
Adopted TMDLs
The Commission adopted these TMDLs on Aug. 6, 2025. EPA approved them on Oct. 14, 2025, at which point they became an update to the state’s Water Quality Management Plan.
- Five TMDLs for Indicator Bacteria in the Mustang, Persimmon, and New Bayou Watersheds
- Response to Public Comment (no comments received)
Reports
H-GAC staff completed a technical report in 2024 that compiled and analyzed all available bacteria data and considered sources of the bacteria and their relative contributions.
Contact Us
Please email tmdl@tceq.texas.gov and mention the Mustang, Persimmon, and New Bayou Watersheds project in the subject line. Or call us at 512-239-6682.
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