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Arroyo Colorado

Background and Goals

The Arroyo Colorado, an ancient distributary channel of the Rio Grande, extends 90 miles from Mission, TX to the Laguna Madre in the Rio Grande Valley. Water quality and fish tissue analyses show that legacy pollutants occur in fish tissues in such concentrations to warrant a fish consumption advisory upstream of the Port of Harlingen. Legacy pollutants are chemicals whose use have been banned or severely restricted, but which can still remain in the environment. In response, the TCEQ conducted a total maximum daily load (TMDL) project to address these pollutants. The ultimate goal of these TMDLs was the reduction of fish tissue contaminant concentrations to levels that constitute an acceptable risk to consumers.

Texas Stream Team staff and volunteers will provide significant resources to implement water quality monitoring, track program accomplishments, and conduct public education and outreach activities. Using the expertise of staff and volunteers, Texas Stream Team will play a substantive role in helping to make this project successful.

Texas Stream Team Activities in the Arroyo Colorado

Texas Stream Team has conducted volunteer water quality monitoring and watershed education activities in the Arroyo Colorado watershed since the early 1990’s. While most of this early activity centered on resacas south of the Arroyo Colorado mainstem, the current focus aims to fulfill recommendations associated with the watershed protection plan partnership. The main objective is to coordinate volunteer water quality monitoring activities at ten sites. Supplemental watershed and nonpoint source pollution prevention education workshops are also occurring.

In 2006, Texas Stream Team (then Texas Watch) began to form partnerships with local and regional organizations that have similar interests and goals. Some of these groups include: Master Naturalists, Texas State Technical College, South Texas College, UT Brownsville, Los Caminos Del Rio, and others including local high schools and interest groups.

Texas Stream Team conducted three water quality monitoring trainings in the watershed and thirty-two monitors were trained. While at the training, monitors learn how to safely collect representative samples for: dissolved oxygen, pH, salinity, specific conductance, Secchi depth transparency, temperature, E.coli, and field observations. These parameters are useful for assessing aquatic life and contact recreation conditions. As indicated in the quality assurance project plan, data that meet quality standards can be used for research and education, local decisions, problem identification, and determining baseline conditions. While most monitors sample from the mainstem, some are choosing sites on “tributaries” and in the Laguna Madre. One monitor is even sampling irrigation waters from the Rio Grande. To date, fifteen sites have been established by monitors.

Coordinated professional water quality monitoring through the TCEQ, Nueces River Authority, and others is imperative in understanding and protecting the health of the Arroyo Colorado. Much of this monitoring takes place during the week at 10-15 sites on a quarterly or monthly basis. The Texas Stream Team program and its water quality monitors anticipate volunteer-generated data may useful in supplementing other data sources. The increased frequency and spatial coverage of volunteer water quality monitoring data will hopefully help the watershed protection partnership in its efforts to restore the Arroyo Colorado.

We would like to thank Texas State Technical College, UT Brownsville, and Los Caminos Del Rio for sponsoring local activities.

A map of Texas Stream Team monitoring locations in the Arroyo Colorado watershed is available for viewing here.

An Arroyo Colorado watershed map is available for viewing here.

2008 Arroyo Colorado Data Report

Arroyo Presentation TMDLS and I-Plan

Twelve TMDLs for Legacy Pollutants in the Arroyo Colorado and Donna Reservoir and Canal. The EPA approved these TMDLs on May 13, 2004.

Total Maximum Daily Loads for Legacy Pollutants in the Arroyo Colorado Above Tidal and the Donna Reservoir and Canal System. The EPA approved these TMDLs on June 14, 2001.

Implementation Plan for Arroyo Colorado and Donna Reservoir and Canal Legacy Pollutant TMDLs. The Commission approved this Implementation plan on September 14, 2001.

Response to public comment on the Arroyo Colorado TMDLs

Response to public comment on the Arroyo Colorado Implementation Plan