Arroyo Colorado

Project photo

The Arroyo Colorado flows through Hidalgo, Cameron and Willacy counties in the Lower Rio Grande Valley of Texas. Water flow in the Arroyo Colorado is sustained by wastewater discharges, agricultural irrigation return flows, urban runoff and base flows from shallow groundwater. Elevated levels of fecal coliform bacteria and low dissolved oxygen have severely impacted recreational use of the lower Arroyo Colorado for fishing and swimming. In 2002 the Texas Commission on Environmental Quality determined in a Total Maximum Daily Load study that a 90 percent reduction of nutrients and biochemical oxygen demand (BOD) was needed to achieve healthy waters.

The Arroyo Colorado Watershed Partnership was established to help restore the watershed and in 2007 it published the Arroyo Colorado Watershed Protection Plan that identified and addressed impairments and concerns in the watershed.

The Texas Water Resources Institute is currently coordinating four projects directed toward implementing the watershed protection plan (WPP). These include educating farmers on techniques that reduce nonpoint source pollution, monitoring the agricultural runoff to evaluate the affects of best management practices (BMPs) implementation, using Soil and Water Assessment Tool (SWAT) to model the current conditions of the watershed and implementing the WPP and obtaining funds for its continuation. For more information, visit the Web site at arroyocolorado.org/.

Projects

Arroyo Colorado Watershed Protection Plan Implementation continues the work outlined in the Arroyo Colorado Watershed Protection Plan, one of the first completed watershed protection plans in Texas. A watershed coordinator coordinates and tracks implementation measures described in the WPP and a grant writer identifies and seeks additional funding to continue watershed protection efforts.

Objectives

  • Publicize and build awareness of the watershed improvement efforts
  • Link partners and projects to available funding sources
  • Analyze all available water quality monitoring data to document changes in the pollutant loading, water quality and habitat during plan implementation

Education of Best Management Practices in the Arroyo Colorado Watershed educates farmers on proper nutrient, pest and irrigation management to reduce the potential for nonpoint source pollution.

Objectives

  • Educate agricultural producers on efficient and environmentally friendly production techniques that protect water quality
  • Promote programs implementing best management practices related to water quality protection

Arroyo Colorado Agricultural Nonpoint Source Assessment project better characterizes agricultural runoff in the Arroyo Colorado, assesses and demonstrates the effects of BMP implementation at the field and sub-watershed level and measures progress toward meeting WPP goals.

Objectives

  • Investigate site-specific differences and temporal variation of water quality in drainage from agricultural production areas
  • Update the land use/land cover map to better reflect current land usage
  • Perform a complete historical data review and analysis to determine efficacy of agricultural BMPs implemented in the watershed

SWAT Model Simulation of the Arroyo Colorado Watershed project is simulating the current pollution loadings using the SWAT computer model, which will help with the reassessment of the needed loading reductions.

Objectives

  • Set up, calibrate and validate a watershed model using measured flow and in-stream measurements of temperature, sediment, BOD and nutrient concentrations
  • Simulate load reduction scenarios for a suite of management measures specified by the Texas State Soil and Water Conservation Board

Accomplishments

  • A physical watershed model was built to increase watershed awareness. More than 7,000 people have viewed the model.
  • Approximately 4, 548 agriculture producers attended educational meetings and workshops.
  • The 2007 soil testing campaign brought in 662 soil samples.
  • An updated land use/land cover map was released.

Collaborators

  • Texas Water Resources Institute, Texas A&M AgriLife
  • Texas AgriLife Extension Service
  • Texas AgriLife Research
  • Texas A&M University–Kingsville
  • Texas A&M University Spatial Sciences Laboratory
  • USDA Natural Resources Conservation Service
  • Arroyo Colorado Watershed Partnership

Funding Agencies

  • Texas State Soil and Water Conservation Board
  • Texas Commission on Environmental Quality
  • U.S. Environmental Protection Agency