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Arroyo Colorado: Surveying Recreational Uses

This is a completed project to evaluate recreational uses of the Arroyo Colorado.
photo of the arroyo colorado
Arroyo Colorado
map of the Arroyo Colorado watershed

Counties: Cameron, Hidalgo, Willacy
Parameter: Bacteria
Basin: Nueces–Rio Grande Coastal
Segment: 2202

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Project Description and Goal

Texas protects the quality of most of the state’s surface waters to make them safe for recreational uses. Activities during which a person might ingest natural waters—such as wading or swimming—are referred to as the “contact recreation” use in the state’s standards for water quality.

In the freshwater portion of the Arroyo Colorado (Segment 2202), fecal bacteria levels are occasionally elevated, which poses a risk to recreational users. In response to these conditions, the TCEQ Total Maximum Daily Load (TMDL) Program initiated a project to survey the recreational uses of Segment 2202. During this project, personnel collected information about the presence or absence of water recreation activities, stream flow, and stream depth, as well as data about other physical conditions necessary for safe contact recreation.

The TCEQ Standards Group used the data collected in this survey to complete a recreational use attainability analysis (RUAA), which is a study used to evaluate the appropriate contact recreation use for a water body. RUAA procedures are standardized to ensure that each analysis is based on sound and repeatable scientific methods.

For an overview of water quality standards and management, read the TCEQ’s publication Preserving and Improving Water Quality.

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Description of Watershed

The Arroyo Colorado is a distributary channel of the Rio Grande that extends about 90 miles from Mission, Texas, to the Laguna Madre in the Lower Rio Grande Valley. The Arroyo Colorado is the major source of fresh water to the lower Laguna, which is an economically and ecologically important resource to the region. Laguna Atascosa National Wildlife Refuge and several county and city parks are located within the Arroyo Colorado watershed. One third of the stream is also used for shipping from the Gulf Intracoastal Waterway to the Port of Harlingen.

Flow in the Arroyo Colorado is sustained by wastewater discharges, agricultural irrigation return flows, urban runoff, and base flows from shallow groundwater. Although an integral part of a major floodway system, water is rarely directly diverted from the Rio Grande into the Arroyo Colorado and direct diversions occur only during major flood events.

The watershed is 705.79 square miles and is part of the larger Nueces–Rio Grande Coastal Basin. The Arroyo Colorado watershed is a flat coastal plain that slopes gently toward the Gulf of Mexico. The fertile farmland, long growing season, and irrigation water from the Rio Grande make this region one of the most productive agricultural areas in the U.S. The mild climate, semi-tropical plants and animals, and many recreational opportunities draw large numbers of people to the Arroyo Colorado watershed.

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Status and Results

TCEQ and the Nueces River Authority conducted a RUAA to evaluate which of the state's four recreational use categories was most appropriate for the Arroyo Colorado. Project staff conducted interviews with many people in the watershed to find out how residents used the Arroyo Colorado for recreation. Staff also collected data about stream flow, stream depth, and other physical conditions that are necessary for safe recreational use. The analysis indicated that the most appropriate use was likely secondary contact recreation. 

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Public Participation

Local participation was crucial to identifying the locations most used for contact recreation. TCEQ informed the public about this project through the Arroyo Colorado Watershed Partnership Steering Committee, at other public meetings in the watershed, and with notices in print and electronic media. All meetings about the project were open to everyone.

Meeting Summaries

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Contact the TMDL Program

Please email and mention the Arroyo Colorado in the subject line. To learn more about the recreational use category assigned to the Arroyo Colorado, contact the Standards Program at Or call the Water Quality Planning Division at 512-239-6682.

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