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Surface Water Quality Monitoring to Support Development and Implementation of Bacteria TMDLs in the Copano Bay Watershed

Copano Bay is located in the San Antonio-Nueces Coastal Basin. The bay covers parts of Aransas and Refugio counties, while the watershed also encompasses Bee, Goliad, Karnes and San Patricio counties. Mission Bay and Port Bay are sub-bays of Copano Bay and are included in Segment 2472. Segment 2472 is the receiving body of the Mission and Aransas Rivers.

Mission River above Tidal (Segment 2002) begins at the confluence of Blanco and Medio Creeks in Refugio County and is 9 miles in length. Mission River Tidal (Segment 2001) begins at a point 4.6 miles downstream of US 77 in Refugio County, is 19 miles in length, and flows into Mission Bay.

Aransas River above Tidal (Segment 2004) begins at the confluence of Poesta and Aransas Creeks in Bee County and is 35 miles in length. Aransas River Tidal (Segment 2003) begins at a point one mile upstream of US 77 in Refugio/San Patricio County, is 6 miles in length, and flows into Copano Bay. The Aransas River forms a portion of the boundary between Refugio and San Patricio Counties, from the Bee County line to the bay.

According to the 2004 Texas Water Quality Inventory and 303(d) List, Copano Bay (Segment 2472) is impaired for bacteria in oyster waters (category 5c) in the area along the southern shore including Port Bay and the area near Bayside. Mission River Tidal (Segment 2001) and Aransas River Tidal (Segment 2003) are both impaired for bacteria (contact recreation).

A Total Maximum Daily Load (TMDL) study to address the bacteria in oyster waters in Copano Bay was initiated in 2003 by the Texas Commission on Environmental Quality (TCEQ). A bacteria loadings model for the Mission and Aransas Rivers watersheds was developed. Nonpoint source contributions were based primarily on land use/land cover information and estimated livestock densities of each county. Point source contributions included wastewater treatment plants, septic systems, and direct deposition by water birds. Bacterial Source Tracking was conducted for the area around and in Copano Bay. Antibiotic resistance analysis was conducted and found contributions from humans/sewage, livestock and ducks. Other wildlife and gulls contributed relatively little contamination.

copanoswqmmap

TCEQ has hosted several public meetings regarding the TMDL project for Copano Bay. Stakeholders at those meetings have expressed concern regarding the limited dataset, both in number of samples used in the analysis and in the geographic extent of samples. In response, TSSWCB has worked with the Nueces River Authority (NRA) to develop and fund this project. Surface water quality monitoring (SWQM) data collected through this project will be utilized to better understand fate and transport mechanisms of bacteria in the Copano Bay watershed. SWQM data collected through this project will be utilized to enhance the TMDL model, as well as, to clarify the 5c impairments in the tidal portions of Mission and Aransas Rivers. Additionally, SWQM data collected through this project will be utilized to monitor water quality improvement and implementation progress of any TMDLs adopted for the Copano Bay watershed.

This project will generate data of known and acceptable quality for monitoring of river stations on Segments 2472 (Copano Bay), 2001 and 2002 (Mission River), and Segments 2003 and 2004 (Aransas River) for field, conventional (TSS and turbidity), flow (non-tidal river segments), and bacteria parameters to support the TMDL for bacteria. Three types of SWQM will be conducted: routine ambient, targeted watershed, and effluent.

This project will provide for up to six monitoring events for each of three years at up to 30 sites. Two dry weather samplings will be scheduled for July and September of each year, and there will an attempt to capture up to four wet/runoff events each year. Specific sampling sites will be re-evaluated each year. Wastewater treatment facilities will be asked to submit end-of-pipe samples for the days of each of the sampling events. There are 16 permitted dischargers in the Copano Bay watershed.

NRA will conduct most of the work performed under this project including technical and financial supervision, preparation of status reports, surface water quality monitoring sample collection, and data management. Bacteria analysis will be conducted by the Texas A&M University-Corpus Christi Microbiology Laboratory and conventional data analysis will be performed by the Lower Colorado River Authority Environmental Services Laboratory. NRA will participate in the Copano Bay TMDL stakeholder meetings in order to summarize activities and achievements made throughout the course of this project. NRA will post monitoring data to their website in a timely manner.

Project Goals/Objectives: Provide quality assured surface water quality monitoring data to support development of bacteria TMDLs for Copano Bay and Mission and Aransas Rivers.

Project Location: Copano Bay watershed (including Mission and Aransas Rivers) in Aransas, Bee, Goliad, Karnes, Refugio and San Patricio Counties

Project Costs: Federal ($214,388); Non Federal Match ($162,945); Total Project: ($377,333)

Project Participant(s): TSSWCB, Nueces River Authority

Project Workplan: 06-15 (PDF, 240 kB)

Quality Assurance Project Plan: 06-15 (PDF, 1.2 MB)