Data from Selected U.S. Geological Survey National Stream
Water-Quality Monitoring Networks (WQN)
By Richard B. Alexander, James R. Slack, Amy S. Ludtke, Kathleen K.
Fitzgerald, and Terry L. Schertz
USGS Digital Data Series DDS-37
During the past 30 years, the U.S. Geological Survey (USGS)
has operated two national stream water-quality networks (see map
below), the Hydrologic Benchmark Network (HBN) and the National Stream
Quality Accounting Network (NASQAN). In these networks, the USGS
systematically monitored streams in watersheds throughout the United States
to provide national and regional descriptions of stream water-quality
conditions and trends and to improve our understanding of the
effects of the natural environment and human activities on water quality.
The HBN, consisting of 63 relatively small, minimally-disturbed watersheds,
provides data for investigating naturally-induced changes in streamflow
and water quality and the effects of airborne substances
on water quality. NASQAN, consisting of 618 larger, more
culturally-influenced watersheds, provides information for tracking water-quality
conditions in major U.S. rivers and streams.
The watersheds in both networks include a diverse set of climatic,
physiographic, and cultural characteristics.
Data from the networks have been used to describe geographic variations
in water-quality concentrations, quantify water-quality trends, estimate
rates of chemical flux from watersheds, and investigate relations of water
quality to the natural environment and anthropogenic contaminant sources.
The networks included 63 HBN stations from 1962-95
and 618 NASQAN stations from 1973-95. Stations located outside
of the conterminous United States for NASQAN included 13 in Alaska, 8 in Hawaii,
6 in Puerto Rico, and 1 in Guam; HBN stations included 1 each in Alaska and Hawaii.
NASQAN and HBN Data on CD-ROM
Much of the historical water-quality and streamflow data collected
by the NASQAN and HBN and supporting documentation including
quality-assurance information have been assembled in an easy-to-use
format on two CD-ROMs. These data are collectively referred to as
Water-Quality Networks (WQN).
The data retrieval tools and ancillary information provided on the
CD-ROMs allow for the efficient and proper use of WQN data. The
CD-ROMs are designed to allow users to efficiently browse text files and retrieve
data for subsequent use in user-supplied software including spreadsheet,
statistical analysis, or geographic information systems.
The data may be extracted from one
of the CD-ROMs (the "DOS disc") using the supplied DOS-based software, and output in
a variety of formats. This software allows the user to search, retrieve,
and output data according to user-specified criteria. Alternatively, the
ASCII form of the WQN data may be accessed on a second CD-ROM (the "ASCII disc")
from user-supplied software including Web browser, spreadsheet,
or word processor.
Access to the contents of the "ASCII disc" is provided in
these Web pages.
Contents of the CD-ROM Data
The WQN data base contains water-quality and streamflow
data collected at 679 NASQAN and HBN stations in the United States.
The water-quality data include a set of
63 physical,
chemical, and biological properties analyzed during more than 60,000
stream visits using relatively consistent sampling and analytical
methods. The water-quality data reflect sampling over a wide range
of streamflow conditions.
Supporting information identifies and describes the water-quality
and streamflow stations, water-quality constituents, and the
methods, remarks, laboratories, sample collection agencies, and the
laboratory measurement accuracy associated with the WQN data.
The WQN data include the following:
Open-File Report 96-337
- The report discusses the objectives and history of the national
networks, characteristics
of the water-quality, streamflow, and quality-assurance data,
and statistical methods for using laboratory quality-control data to
evaluate the accuracy of stream water-quality measurements.
The report is entitled
"Data from Selected U.S. Geological Survey National Stream Water-
Quality Monitoring Networks (WQN) on CD-ROM" by R.B.
Alexander, A.S. Ludtke, K.K. Fitzgerald, and T.L. Schertz, U.S.
Geological Survey Open-File Report 96-337.
Water Quality and Streamflow Data
- Uniformly-sampled (i.e., semi-annually to monthly) stream water-quality
data include 63 physical, chemical, and biological properties
(122 water constituents
including the dissolved, suspended,
and total forms). These data include physical/field measurements
(e.g., temperature, instantaneous streamflow, pH, suspended
sediment), major ions, nutrients, organic carbon, radiochemicals
biological measurements (e.g., fecal bacteria, phytoplankton,
and periphyton), and inorganic trace elements. With the exception
of the periphyton data, which reflect substrate conditions, all
measurements reflect conditions in the water column.
- Daily mean records of streamflow span time periods corresponding to
the water-quality data. These data can be used with the
water-quality data to derive estimates of flux. [These data
are available only on the ASCII disc, which can be accessed through
user-supplied software]
- Supporting information on the
water-quality measurements includes constituent and parameter
code lists, definitions, and the sample collection agencies,
laboratories, and laboratory analytical methods associated with
the stream water-quality data. Information on the collection agencies,
laboratories, and lab methods have been stored in the water-quality digital data
files on a frequent basis since the early to mid 1980s.
- Water-quality and streamflow
station attributes include drainage
area, latitude, longitude, the dates of station operation,
county, state, and hydrologic unit code (HUC) identifiers, and
drainage basin population for 1990 and land-cover statistics
for 1987.
Blind Sample Program (BSP) Data
- Laboratory quality-control data for 34 chemical constituents
can be used to evaluate the measurement bias and variability of
national network stream water-quality data for the period 1985-95.
The quality-control data
were collected through the Blind Sample Program, a USGS program
that regularly monitors the quality of laboratory analytical results
through the use of stable, homogeneous standard reference water samples.
Quality-Assurance Information
- Documentation describes changes in field and laboratory methods, constituent
coverage, network operations, reporting conventions, and sample
contamination that may affect the use and interpretation of
WQN stream water-quality data. The documentation includes USGS
water-quality technical memoranda that describe national network operations and
important changes in field and laboratory methods.
Bibliography
- More than 160 publications describe national network field and laboratory
methods, network characteristics, summaries and interpretations of network
data at the national, regional, and local levels, and statistical
and computer software methods that have been developed for use with
data having characteristics similar to those of the national network
data.
Additional Documentation
- Various files include USGS contacts,
acknowledgements, descriptions of the data structure of the
CD-ROMs, and brief overview of the CD-ROM data.
More Information about WQN.
U.S. Geological Survey Home Page
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Last modified: Fri Mar 2 08:12:13 EST 2001
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