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Oso Bay and Oso Creek

Background and Goals

Oso Bay is an enclosed, shallow body of water situated along the southern shore of Corpus Christi Bay, with a surface area of approximately seven square miles. The bay exchanges saltwater with Corpus Christi Bay and receives fresh water from Oso Creek, a stream whose flow is dominated by discharges subject to permit. Ecologically, Oso Bay provides habitat for many plants and animals, and plays an influential role in water purification and storm protection.

Water quality testing found that concentrations of bacteria are elevated in both the bay and the creek, which may pose a risk to people who swim or wade in them. Swimming and wading are called “contact recreation” in the state’s standards for water quality; the term refers to all recreation in which people come in direct contact with the water. The goal of this project is to reduce bacteria concentrations to within acceptable risk levels for contact recreation.

In March 2006, the Texas Commission on Environmental Quality (TCEQ) separated development of the Total Maximum Daily Load (TMDL)s for the bay and the creek, with the advice and consent of the stakeholder advisory group. The TMDLs will be drafted and processed as separate but related documents.

Texas Stream Team (TST) 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, TST will play a substantive role in helping to make this project successful.

TST Activities in Oso Bay and Oso Creek

In conjunction with the TES course at Texas A&M Corpus Christi (TAMU-CC), the program conducted an extended 3-day NPS education session with a concentration on bacteria. On day one, the field component consisted of training, including an Oso Creek Watershed tour. On day two, they applied the training knowledge from the watershed tour, and read E.coli results on day three. This extended training was designed to support the need for additional outreach in TMDL Project Areas.

The TST Watershed Protection Meeting which was scheduled for August was rescheduled for the fall. Planning partners identified solid waste issues, colonias and bacteria issues as the main topics to be covered by the meeting. TST and the Coastal Bend Council of Governments (CBOG), who TST was coordinating outreach with in the Coastal Bend, agreed to move the meeting to the fall in light of a delay in United States Environmental Protection Agency (EPA) approving a change in the CBCOG’s 319 work plan. This change was requested due to the fact that the sites targeted for cleanup in the grant were cleaned up in conjunction with road repairs. In August, TST attended a planning session for grant partners which focused on next steps. It was agreed that solid waste issues would not play a key role in the focus of the regional meeting, and that the agenda could focus on bacteria issues in the Oso Bay and Oso Creek. An effort will be made to invite colonia residents. TST staff toured one of the colonias in conjunction with the August planning session, and confirmed that standing water in these communities may be a water quality concern that the program may want to address at the watershed protection meeting.

The August meeting established key contacts for TST at the Coastal Bend Bays and Estuaries Program (CBBEP), the Coastal Bend Bays Foundation (CBBF) and the Harte Research Institute (HRI) for Gulf of Mexico Studies. Follow-up from this meeting in September resulted in a flurry of activity and a watershed protection meeting in November 2007.

In 2008, the TST volunteer water quality monitoring network of actively monitored sites in the Oso Watershed increased dramatically. Training of additional students and local community members at TAMU-CC are expected to yield additional monitoring sites. A presentation of professional and volunteer water quality data was  scheduled for summer 2009.

Public Participation

An advisory group is established to advise TCEQ on these projects. Advisory group meetings are open to all. Find out more about meetings and membership of the advisory group.

TMDL for Oso Bay

On August 22, 2007, the commission adopted a TMDL for Oso Bay. If approved by the EPA, the TMDL will become part of the state's Water Quality Management Plan.

Project Documents

Oso Creek and Oso Bay Bacteria TMDL Model Report - 2006 (PDF)

Oso Creek and Oso Bay Bacteria TMDL Model Report - 2005 (PDF)

Map Showing Model Bacteria Loading and Land Use (PDF)

Water Quality and Biological Characterization of Oso Creek and Oso Bay, Corpus Christi, Texas (PDF)


For more information:

Please send an e-mail to, and mention the Oso Bay and Oso Creek Bacteria project in the subject line. Or call the TCEQ project manager, Jason Leifester, at (512)239-6682.