Little Brazos River Bacteria Assessment

Project photo

Elevated levels of fecal bacteria in Texas water bodies currently cause more than 50 percent of all water quality impairments in the state. These bacteria come from all warm-blooded animals and are found in all Texas water bodies regardless of their location or type. Because of these widespread bacteria impairments, the Texas Commission on Environmental Quality and the Texas State Soil and Water Conservation Board established a joint task force to outline a methodology for effectively developing bacteria TMDLs to address these impairments and are now employing this process in several locations statewide.

In 2002, water quality data analysis determined that Campbells, Mud, Pin Oak, Spring and Walnut creeks — tributaries of the Little Brazos River (LBR) located in Robertson County — had bacteria concentrations that exceeded state water quality standards. These five creeks are now listed on the Texas Water Quality Inventory and §303(d) List for failing to meet their designated contact recreation uses. The creeks exhibit similar land cover and land use patterns and have similar water quality characteristics.

Through three partnered projects, 1) Assessment of Contact Recreation Use Impairments and Watershed Planning for Five Tributaries of the Little Brazos River, 2) Bacteria Source Tracking for Little Brazos River Tributaries Bacteria Assessment and 3) Modeling for Little Brazos River Tributaries Bacteria Assessment, project personnel are assessing water quality and sources and potential types of bacterial pollution in these watersheds along with the designated recreation uses. Findings from each project will be combined to formulate the final assessment for each of the LBR tributaries.

Projects

Assessment of Contact Recreation Use Impairments and Watershed Planning for Five Tributaries of the Little Brazos River is assessing contact recreation use impairments and supporting watershed planning by facilitating public participation and coordinating stakeholder involvement in decision making, conducting a watershed source survey and collecting additional water quality monitoring data.

Bacteria Source Tracking for Little Brazos River Tributaries Bacteria Assessment is conducting bacteria source tracking analysis on water samples collected by the Brazos River Authority and identifying the sources of bacteria collected from each creek studied.

Modeling for Little Brazos River Tributaries Bacteria Assessment is developing a detailed GIS map of the watersheds that includes watershed features that may contribute bacteria to each creek. This project is developing a model for the watersheds and using information from the GIS map and water quality data to identify areas of the watershed with the most potential for bacteria contribution. It is also developing load duration curves for each creek that identify needed bacteria load reductions.

Objectives

  • Assess contact recreation use impairments
  • Facilitate public participation and coordinate stakeholder • involvement in decision making and watershed planning activities
  • Develop a comprehensive GIS inventory and conduct a watershed source survey
  • Conduct bacterial source tracking to identify sources of bacteria
  • Analyze water quality data using load duration curves
  • Use spatially explicit modeling to identify probable bacteria source contribution areas

Collaborators

  • Texas State Soil and Water Conservation Board
  • Brazos River Authority
  • Texas Water Resources Institute
  • Texas AgriLife Research
  • Robertson County Soil and Water Conservation District

Funding Agency

  • Texas State Soil and Water Conservation Board