GIS Coverage for the National Water-Quality Assessment (NAWQA) Program Retrospective Database for Nutrients in Surface Water: Monitoring LocationsEntry ID: NAWQAHIS
Abstract: The retrospective database is a compilation of historical water-quality and
ancillary data collected before NAWQA Study Units initiated sampling in 1993.
This coverage contains the point locations of monitoring locations where
historical water-quality data was collected. Water-quality data were obtained
by study-unit personnel from the U.S. Geological Survey (USGS) National Water
Information ... System (NWIS), from records of State water-resource agencies, and
from STORET, the U.S. Environmental Protection Agency national database.
Ancillary data describing characteristics of sampled sites were compiled by
NAWQA Study Units or obtained from national-scale digital maps.
Mueller and others (1995) used this data to determine preexisting water-quality
conditions in the first 20 NAWQA Study Units that began in 1991. Also, Nolan
and Ruddy (1996) used the data to describe areas of the United States at risk
of nitrate contamination of ground water.
The retrospective database includes over 22,000 surface-water samples. The
surface-water data are for samples collected during 1980-90 at sites that had a
minimum of 25 monthly samples. Year of sampling is included in the
retrospective database because it was reported most often by the various Study
Units. Year of sampling also is convenient because some Study Units reported
median constituent concentrations. If sampling date ranges for median values
fell within a single year, then year of sampling was retained in the national
data set for that sample.
Because sampling, preservation, and analytical techniques associated with these
historical data changed during the period of record and are different for
different agencies, reported nutrient concentrations were aggregated into the
following groups: (1) ammonia as N, (2) nitrate as N, (3) total nitrogen, (4)
orthophosphate as P, and (5) total phosphorus. For example, ammonia includes
both ammonium ions and un-ionized ammonia. More information on methods used to
aggregate constituent data is available in the report by Mueller and others
Much of the ancillary data, such as well and aquifer descriptions and land-use
classification for surface-water drainage basins, were provided by NAWQA Study
Units. Data evaluated at the national scale include land use, soil hydrologic
group, nitrogen input to the land surface, and the ratios of pasture or
woodland to cropland.
Land-use classification of surface-water sites is based on Anderson Level I
categories (Anderson and others, 1976). Land use at surface-water sites was
classified by NAWQA Study Unit personnel based on the Anderson Level I
categories. Many surface-water sites were affected by mixed land uses, such as
Forest and Agricultural, or Agricultural and Urban. Surface-water sites with
very large drainage areas (greater than 10,000 square miles) were considered to
be affected by multiple land uses, and were designated as Integrated land use.
More detailed descriptions of the land-use categories in the retrospective
database are given by Mueller and others (1995).
Soil hydrologic group was determined from digital maps compiled by the U.S.
Soil Conservation Service (1993). The categorical values (A, B, C, and D) from
the digital maps were converted to numbers to permit aggregation (Mueller and
others, 1995). Surface-water sites were assigned the area-weighted mean for
soil mapping units in the upstream drainage basin. Many surface-water sites did
not have digitized basin boundaries available, so hydrologic group could not be
Fertilizer and manure applications were estimated from national databases of
fertilizer sales (U.S. Environmental Protection Agency, 1990) and animal
populations (U.S. Bureau of the Census, 1989). Nitrogen input by atmospheric
deposition was derived from data provided by the National Atmospheric
Deposition Program/National Trends Network (1992).
Population data were obtained from the U.S. Bureau of the Census (1991). Total
population in the upstream drainage was compiled for the surface-water data
Within the database, concentrations less than detection are reported as
negative values of the detection limit. Missing values are indicated by a
decimal point. (During processing of the tabular data, these decimal points
were replaced will NULL values; See Data_Quality_Information section.
Historical data can be of limited use in national assessments because of
inconsistencies between and within agencies in database structure and format
and in sample collection, preservation, and analytical procedures. For example,
changes in sample collection and analytical procedures can cause shifts in
constituent concentrations that are unrelated to possible changes in
environmental factors. See Mueller and others (1995) for assumptions and
limitations associated with the retrospective database.
[Summary provided by the EPA.]
Data Set Citation
Dataset Originator/Creator: Hitt, K.J. and Nakagaki
Dataset Title: National Water-Quality Assessment (NAWQA) Program Retrospective Database for Nutrients in Surface Water : Monitoring Locations
Dataset Release Date: 1999-07-01
Dataset Release Place: Reston, VA
Dataset Publisher: USGS
Data Presentation Form: Map
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > GREAT LAKES > Western Lake Michigan Drainages
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > CONNECTICUT > Connecticut, Housatonic, and Thames River Basins
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > FLORIDA > Apalachicola-Chattahoochee-Flint River Basin
HUMAN DIMENSIONS > ENVIRONMENTAL GOVERNANCE/MANAGEMENT > WATER MANAGEMENT
HUMAN DIMENSIONS > PUBLIC HEALTH
HUMAN DIMENSIONS > ENVIRONMENTAL GOVERNANCE/MANAGEMENT > LAND MANAGEMENT
HUMAN DIMENSIONS > ENVIRONMENTAL GOVERNANCE/MANAGEMENT > LAND MANAGEMENT > LAND USE CLASSES
TERRESTRIAL HYDROSPHERE > GROUND WATER > GROUND WATER FEATURES > AQUIFERS
TERRESTRIAL HYDROSPHERE > GROUND WATER > GROUND WATER FEATURES > WATER TABLE
TERRESTRIAL HYDROSPHERE > SURFACE WATER > SURFACE WATER FEATURES > LAKES/RESERVOIRS
TERRESTRIAL HYDROSPHERE > SURFACE WATER > SURFACE WATER FEATURES > RIVERS/STREAMS
TERRESTRIAL HYDROSPHERE > WATER QUALITY/WATER CHEMISTRY > NITROGEN COMPOUNDS
TERRESTRIAL HYDROSPHERE > WATER QUALITY/WATER CHEMISTRY > PH
TERRESTRIAL HYDROSPHERE > WATER QUALITY/WATER CHEMISTRY > TRACE METALS
HUMAN DIMENSIONS > ENVIRONMENTAL GOVERNANCE/MANAGEMENT > ENVIRONMENTAL ASSESSMENTS
ISO Topic Category
Quality Mueller and others (1995) used this data to determine preexisting
water-quality conditions in the first 20 NAWQA Study Units that began
in 1991. Also, Nolan and Ruddy (1996) used the data to describe areas
of the United States at risk of nitrate contamination of ground water.
... Original tabular data were compiled by USGS as described in the Data
Summary section. Tabular data was downloaded from the USGS web site and
was prepared for use in EPA Clean Air Markets Division.s (CAMD)
Geographic Information System. Latitude/Longitude coordinates were
converted to decimal degrees and used to create a shapefile using
ArcView 3.2. The shapefile was imported into ArcInfo 7.2.1 and
projected first into Albers, NAD27 and then into Albers, NAD83.
Access Constraints None
Use Constraints Historical data can be of limited use in national assessments
because of inconsistencies between and within agencies in database
structure and format and in sample collection, preservation, and
analytical procedures. For example, changes in sample collection and
analytical procedures can cause shifts in constituent concentrations
that are unrelated to possible changes in environmental factors. See
Mueller and others (1995) for assumptions and limitations associated
with the retrospective database.
Data Set Progress
Distribution Media: FTP
Distribution Size: 6184720
Distribution Format: ArcInfo export format
Fees: No fees
Distribution Media: FTP
Distribution Size: 16303646
Distribution Format: ArcView shapefile
Fees: No fees
Anderson, J.R., Hardy, E.E., Roach, J.T., and Witmer, R.E., 1976, A
land use and land cover classification system for use with remote
sensor data: U.S. Geological Survey Professional Paper 964, 28 p.
Fegeas, R.G., Claire, R.W., Guptill, S.C., Anderson, K.E., and Hallam,
C.A., 1983, Land use and land cover digital data: U.S. Geological
Survey Circular 895-E, 21 p.
Mueller, D.K., Hamilton, P.A., Helsel, D.R., Hitt, K.J., and Ruddy,
B.C., 1995, Nutrients in ground water and surface water of the United
States--An analysis of data through 1992: U.S. Geological Survey
Water-Resources Investigations Report 95-4031, 74 p.
National Atmospheric Deposition Program (NRSP-3)/National Trends
Network, 1992: Ft. Collins, CO, NADP/NTN Coordination Office.
Nolan, B.T., and Ruddy, B.C., 1996, Nitrate in ground waters of the
United States--Assessing the risk: U.S. Geological Survey Fact Sheet
Puckett, L.J., 1995, Identifying the major sources of nutrient water
pollution: Environmental Science and Technology, v. 29, n. 9,
U.S. Bureau of the Census, 1989, Census of agriculture 1987--Final
county file: Washington, D.C., Data Users Services Division.
U.S. Bureau of the Census, 1991, Census of population and housing,
1990: Public Law 94-171 data for the United States: Washington, D.C.,
U.S. Environmental Protection Agency, 1990, County-level fertilizer
sales data: Washington, D.C., Office of Policy, Planning, and
Evaluation, USEPA PM-221.
U.S. Soil Conservation Service, 1993, State soil geographic data base
(STATSGO)--Data users guide: Miscellaneous Publication Number 1492, 88
Extended Metadata Properties
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Creation and Review Dates
DIF Creation Date: 2002-11-15
Last DIF Revision Date: 2017-08-23