U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2013–3038

July 2013

The National Water-Quality Assessment (NAWQA) Program 

Planned Monitoring and Modeling Activities for Texas, 2013–23

Printed on recycled paper

The U.S. Geological Survey’s (USGS) National Water-Quality Assessment (NAWQA) Program 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. 

Surface-Water Activities 

NAWQA will characterize the status and trends of surface-water 

quality and aquatic ecosystems by monitoring ambient water-quality 

and ecological conditions through a National Fixed Site Network 

(NFSN). The NFSN will be the primary source of data for timely 

tracking and systematic annual reporting 

of national ambient conditions. The 

NFSN consists of 61 large river sites and 

39 wadeable stream sites, most of which 

have been monitored by the USGS for 

20 years or more. NFSN data, as well 

as data collected by State and other 

agencies, including various agencies 

in Texas, support the development and 

refinement of USGS regional waterquality models such as ones that can be 

used to estimate nutrient loads in Texas’ 

river systems delivered to the Gulf of 

Mexico by Texas’ rivers and streams. 

Five NFSN monitoring sites are 

planned for Texas, three large river 

sites (Brazos, Rio Grande, and Trinity 

Rivers), and two wadeable streams, 

one draining a small watershed that is 

minimally disturbed by development 

(Frio River) and one that drains the 

heavily urbanized Dallas metropolitan 

area (White Rock Creek) (fig. 1 and 

table 1). Each of these sites will be 

sampled between 6 and 24 times 

per year, every year for basic waterquality properties (pH, conductance, 

dissolved oxygen, and temperature), 

major ions, nutrients, organic carbon, 

and suspended sediment, and at four of 

the five sites, a comprehensive suite of 

pesticides and their breakdown products 

(table 1). At the two wadeable stream 

sites, ecological sampling of algal, 

macroinvertebrate, and fish communities will be sampled annually. By 

providing long-term, nationally consistent data on a suite of pesticides 

and other analytes not typically analyzed for by other agencies, 

NAWQA stream and river monitoring complements the extensive 

surface-water-quality monitoring done by the Texas Clean Rivers 

Program and its partners.

Figure 1. 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.
Groundwater Activities

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. Over the next decade, 

groundwater assessments are planned in 20 principal aquifers, 

which collectively account for more than 75 percent of the national 

groundwater used for drinking water. Water-quality data will be 

collected from the Coastal Lowlands aquifer of Texas (also referred 

to as the Gulf Coast aquifer system) and used with groundwater 

flow models to estimate the amount of groundwater available to the 

aquifer, the aquifer’s vulnerability to contamination, and to gain 

an understanding of the way groundwater quality may respond to 

changes in climate, land use, and water use 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 (fig. 1 and table 2). 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. 

Table 1. Texas streams and rivers selected for monitoring by National Water-Quality Assessment (NAWQA) Program, 2013–23.

[USGS, U.S.Geological Survey]

USGS

station number USGS station name Site type

Ecological

sampling

Number of 

samples

per year

Sampling history

(approximate total 

samples/ time period)

08195000 Frio River at Concan, Tex. wadeable reference stream yes 6 150/ 1965–2004

08057200

White Rock Creek at Greenville 

Avenue, Dallas, Tex. wadeable urban stream yes 24 200/ 1995–2011

08057410 Trinity River below Dallas, Tex. large river no 18 750/ 1967–2012

08475000 Rio Grande near Brownsville, Tex. large river no 12 350/ 1966–2012

08116650 Brazos River near Rosharon, Tex. large river no 14 350/ 1968–80, 2008–12

Opportunities For Partnering With the

U.S. Geological Survey

Because of budget cuts, monitoring has been scaled back or 

eliminated from some long-term stations in Texas in the past few 

years within the NAWQA program (fig. 1). The NAWQA Program 

and the USGS Texas Water Science Center hope to restore monitoring 

at surface-water or groundwater stations where it has been scaled 

back or eliminated through cost-sharing efforts with USGS partners. 

The USGS welcomes opportunities to collaborate with other agencies 

to restore monitoring at inactive sites or to bolster planned monitoring 

or modeling activities. This could include expanding data collection 

at existing sites by adding continuous water-quality sensors or by 

augmenting laboratory analyses for additional chemical constituents 

to samples collected from NAWQA groundwater networks. Shared 

activities and funding increases the engagement of all levels of 

government—from local and State to national. Shared activities 

and funding maintain robust network operations, keep observations 

relevant to diverse uses, enhance cost-effectiveness, and aid network 

optimization and leveraging efforts.

By Patricia Ging

U.S. Geological Survey field crew sampling a National Water-Quality 

Assessment (NAWQA) Program surface-water site.

Table 2. National Water-Quality Assessment (NAWQA) Program 

groundwater studies planned in Texas, 2013–23.

Groundwater

network

Planned 

fiscal 

year for 

sampling

Number 

of wells 

Sampling history 

(approximate

total samples/

time period)

Coastal Lowlands Major

Aquifer Study 2014 64 145/ 1994–2011

Coastal Lowlands Land

Use Study 2015 29 60/ 2003–11

Edwards Major

Aquifer Study 2016 30 200/ 1996–2012

Edwards Land Use Study 2018 31 125/ 1998–2012

To discuss partnering opportunities, or for more information 

about NAWQA activities in Texas please contact: 

Robert L. Joseph, Director (rljoseph@usgs.gov) or 

Patricia Ging, Hydrologist (pbging@usgs.gov)

1505 Ferguson Lane, Austin, TX 78754

Telephone (512) 927–3500 or visit http://tx.usgs.gov