National Water-Quality Assessment Project in Texas - Groundwater Activities

Science Center Objects

The USGS National Water-Quality Assessment (NAWQA) Project was established by Congress in 1992 to answer the following question:

What is the status of the Nation’s water quality and is it getting better or worse?

Since 1992, NAWQA has been a primary source of nationally consistent data and information on the quality of the Nation’s streams and groundwater. Data and information obtained from objective and nationally consistent water-quality monitoring and modeling activities provide answers to where, when, and why the Nation’s water quality is degraded and what can be done to improve and protect it for human and ecosystem needs. For NAWQA’s third decade (2013–23), a new strategic Science Plan has been developed that describes a strategy for building upon and enhancing the USGS’s ongoing assessment of the Nation’s freshwater quality and aquatic ecosystems.

At the Texas Water Science Center (TXWSC), NAWQA activities focus on two main areas: surface water and groundwater.


NAWQA is the only Federal program that assesses the status of the Nation’s groundwater quality and reports on how these conditions are changing over time.

Groundwater monitoring planned for Texas over the next decade includes

  • resampling of two domestic well major aquifer study networks in the Coastal Lowlands and Edwards aquifers, and
  • resampling of two shallow monitoring well land-use study networks to assess trends in groundwater quality in aquifers beneath San Antonio and Houston.

NAWQA will also develop a new network that will sample 60 public supply wells to represent depths deeper than those tapped by domestic wells in the Coastal Lowlands, Texas Coastal Uplands, and Mississippi Embayment aquifer system across Texas and other Gulf Coast States.

Wells will be sampled once for

  • basic water-quality properties (pH, conductance, dissolved oxygen, temperature),
  • major ions,
  • nutrients,
  • organic carbon,
  • trace elements,
  • age-dating tracers,
  • radionuclides, and
  • an extensive suite of pesticides, volatile organic compounds, pharmaceuticals, and hormones.

Analytical methods will be used to measure concentrations as low as economically and technically feasible. The resulting data will be used to detect subtle changes in groundwater quality, providing an early warning system of sorts before any appreciable changes occur. A subset of the wells will be sampled for microbial contaminants.


Map of NAWQA study areas in Texas

Streams and river locations in Texas that are part of the National Fixed Site Network that will be monitored throughout the year, every year, through 2023 as well as the locations of groundwater networks that are scheduled for sampling over the next decade. Also shown are inactive National Fixed Site Network sites and groundwater networks.

(Public domain.)