National Water-Quality Program Monitoring Networks, Arizona, 2013-2023

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The Arizona Water Science Center collects water-quality data from stream and aquifer sites in networks that are part of the National Water-Quality Program (NWQP) and the National Stream Quality Accounting Network (NASQAN).

Map showing National Water-Quality Monitoring Network, Arizona Stream Monitoring Sites

National Water-Quality Monitoring Networks, Arizona, stream monitoring sites

This program provides an understanding of water-quality conditions, whether conditions are getting better or worse over time, and how natural features and human activities affect those conditions. Regional and national assessments are possible because of a consistent study design and uniform methods of data collection and analysis. Monitoring data collected from the sampling network are integrated with geographic information on hydrological characteristics, land use, and other landscape features in models to extend water-quality understanding to unmonitored areas. Local, State, Tribal, and national stakeholders can use such information to design and implement strategies for managing, protecting, and monitoring water resources in many different hydrologic and land-use settings across the Nation. Monitoring program plans for 2013–2023 are summarized below and in USGS Fact Sheet 2013-3008.

Stream Monitoring

Water-quality monitoring for 2013 to 2023 will be done at a network of 100 stream sites across the nation, including three in Arizona (see table and map). Most are long-term USGS monitoring sites that have more than 20 years of data. The national network includes 61 large river sites that will provide basic coverage of large-scale trends in nutrient, sediment, and contaminant loading to inland or coastal receiving waters, and 39 wadeable stream sites that will be used to track trends in water-quality and ecosystem condition at urban, agricultural, and undeveloped watersheds selected to represent the national diversity of environmental settings. Most sites will be sampled 6 to 18 times per year for a wide range of contaminants. At the 39 wadeable stream sites, including one in Arizona, stream-ecology evaluations of the condition of algal, macroinvertebrate, and fish communities will be conducted annually.

Table showing NWQP-Arizona stream monitoring sites, plans for 2013-2023

NWQP Stream Monitoring Sites, Arizona, sampling plans for 2013-2023

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Aquifer Monitoring

Water-quality monitoring studies are planned in 20 principal aquifers across the nation, which collectively account for more than 75 percent of the national groundwater used for drinking water. Monitoring data will be statistically analyzed to generate maps of selected contaminant occurrence at the depth zones used for domestic and public supply. Monitoring data will also be used to assess how groundwater supplies are changing over time and why.

  • Sampling Existing Networks for Assessing Trends — About 2,500 wells distributed among 79 existing networks that were previously sampled between 1993 and 2013 will be resampled over the next decade for key water properties, nitrate, and trace elements to assess how shallow groundwater quality is changing in principal aquifers beneath urban and agricultural land. Such efforts will include resampling a network of 35 wells in the West Salt River Valley (likely in year 2018; see map above for location), a basin which contains much of Phoenix and its western suburbs. Selected wells will also be sampled for pesticides, contaminants of emerging concern (pharmaceuticals, hormones, and high production volume chemicals), radiochemicals, microbial contaminants, and tracers that indicate the approximate age of the groundwater.

  • Sampling New Networks to Define Conditions at Depth — In addition to resampling networks described above, about 1,500 deep public supply wells will be sampled across the nation during 2013–2023 to help characterize water-quality conditions in deeper parts of principal aquifers that were not examined in previous decades. In 2013, this effort included sampling about 60 wells completed in Basin and Range basin-fill aquifers within Arizona, California, Nevada, New Mexico, and Utah (see map above for extent in Arizona). Samples from these wells were analyzed for selected water properties, nutrients, trace elements, pesticides, contaminants of emerging, radiochemicals, microbial contaminants, and tracers that indicate the approximate age of the groundwater.



For more information, please contact:

Stream Monitoring
Nick Paretti
(520) 670-6671 x301