Risk of nitrate contamination in groundwaters of the United States-- A national perspective

Federal Geographic Data Committee (FGDC) Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Reference_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: Nolan, B.T., Ruddy, B.C., Hitt, K.J., and Helsel, D.R.

Publication_Date: 19970101

Title: Risk of nitrate contamination in groundwaters of the United States-- A national perspective

Edition: 2

Geospatial_Data_Presentation_Form: Map

Series_Information:

Series_Name:

Issue_Identification:

Publication_Information:

Publication_Place: Reston, Virginia, USA

Publisher: U.S. Geological Survey [Digital spatial data]

Other_Citation_Details:

Environmental Science and Technology [Hard copy]

Online_Linkage: http://water.usgs.gov/lookup/getspatial?gwrisk

Description:

Abstract:

This map was designed to present patterns of risk for nitrate contamination at large regional or national scales. Knowing where and what type of risks to ground water exist can alert water-resources managers and private users of the need to protect water supplies. By targeting regions with the highest risk of nitrate contamination, resources can be directed to areas most likely to benefit from pollution-prevention programs and long-term monitoring. Nitrate contamination of ground water occurs in patterns based on "input" factors (population density and nitrate contribution from fertilizer, manure, and atmospheric deposition) and "aquifer vulnerability" factors (soil drainage characteristic and woodland/cropland ratio in agricultural areas). Areas with high nitrogen input, well-drained soils, and low woodland to cropland ratio have the highest potential for contamination of ground water. The patterns of risk for nitrate contamination of ground water were compiled in a national map as described in Nolan and others (1997). The digital version of the national map is included here. The risk patterns still are being refined as better data sets become available, and this map should not be considered to be the "final" version of the patterns. Procedures_Used: Soil drainage characteristic was determined from data on soil hydrologic group in the STATSGO (State Soil Geographic) data base (U.S. Soil Conservation Service, 1994a,b). The STATSGO categorical values for hydrologic group were converted to numbers in order to generalize (by area-weighted average) the hydrologic group for each soil map unit. The threshold level of 2.5 was determined; soils with a value less than 2.5 were considered to be well-drained soils (similar to the STATSGO hydrologic group values of A or B) and soils with a value greater than or equal to 2.5 were considered to be poorly-drained soils (similar to the STATSGO hydrologic group values of C or D). The original map unit level data was converted from a coverage (vector data) to a grid in order to facilitate overlaying the data layers using ARC/INFO GRID processing. The grid was divided into 2 groups, those cells having a hydrologic group value less than 2.5 and those cells having a hydrologic group value greater than or equal to 2.5. The extent of woodland and cropland in agricultural areas was compiled from the 1992 Census of Agriculture (U.S. Bureau of the Census, 1995) in which the acres of woodland and cropland are compiled by county. The woodland to cropland ratio was calculated by dividing the acres of woodland by the acres of cropland. The ratio represents the extent of woodland in relation to cropland in agricultural areas of the Southeast, where dilution, denitrification, and vegetative uptake likely attenuate nitrate concentration in ground water. This county level information was converted from a coverage to a grid in order to facilitate overlaying the data layers. The grid was divided into 2 groups, those cells having a woodland/cropland ratio less than 0.3 and those cells having a woodland/cropland ratio greater than or equal to 0.3. Population density was determined from 1990 population data compiled by census block group (U.S. Bureau of the Census, 1991) and was calculated for each census block group by dividing the number of people in the block group by the land area of the block group. This census block group information was converted from a coverage to a grid in order to facilitate overlaying the data layers. The grid was divided into 2 groups, those cells having greater than 386 people per square kilometer and those cells having less than or equal to 386 people per square kilometer. Nitrogen loading was determined by combining nitrogen input from fertilizer (Battaglin and Goolsby, 1994), manure (Smith and others, 1997), and atmospheric deposition (Smith and others, 1997). This county level nitrogen data was converted from a coverage to a grid in order to facilitate overlaying the data layers. The grid was divided into 2 groups, those cells having greater than 2,100 kilograms per square kilometer and those cells have less than or equal to 2,100 kilograms per square kilometer. These four grids were combined into one output grid. The sixteen values from the input grids were consolidated into four risk categories for nitrate contamination of ground water in the conterminous United States: Group 4 -- high -- nitrogen loading greater than 2,100 kilograms per square kilometer or population density greater than 386 people per square kilometer; hydrologic group less than 2.5 and woodland to cropland ratio less than 0.3. Group 3 -- moderately high -- nitrogen loading greater than 2,100 kilograms per square kilometer or population density greater than 386 people per square kilometer; hydrologic group greater than or equal to 2.5 or woodland to cropland ratio greater than or equal to 0.3. Group 2 -- moderately low -- nitrogen loading less than or equal to 2,100 kilograms per square kilometer and population density less than or equal to 386 people per square kilometer; hydrologic group less than or equal to 2.5 and woodland to cropland ratio less than 0.3. Group 1 -- low -- nitrogen loading less than or equal to 2,100 kilograms per square kilometer and population density less than or equal to 386 people per square kilometer; hydrologic group greater than or equal to 2.5 or woodland to cropland ratio greater than or equal to 0.3. The data set is provided in ascii format as well as exported ARC/INFO GRID format. In the ascii file, only the field called "S1" is included. The field called "VALUE" is not included. The projection file needed for the ascii format of the data set is: Projection ALBERS Datum NAD27 Zunits NO Units METERS Spheroid CLARKE1866 Xshift 0.0000000000 Yshift 0.0000000000 Parameters 29 30 0.000 /* 1st standard parallel 45 30 0.000 /* 2nd standard parallel -96 0 0.000 /* central meridian 23 0 0.000 /* latitude of projection's origin 0.00000 /* false easting (meters) 0.00000 /* false northing (meters) The retrospective database for nutrients in ground water and surface water is available through the internet at "http://water.usgs.gov/nawqa/nutrients/datasets/retrodata.html". The current version of the map also appears in Nolan and others (1998), which is available through the internet at "http://water.usgs.gov/nawqa/wcp/index.html".

Purpose:

Not Available

Supplemental_Information:

REFERENCE: 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 FS-092-96, Reston, Va. Available through the internet at URL: http://pubs.usgs.gov/fs/1996/fs-092-96/fs092-96.html

Supplemental_Information:

REFERENCE: Nolan, B.T., Ruddy, B.C., Hitt, K.J., and Helsel, D.R., 1997, Risk of nitrate contamination in groundwaters of the United States--A national perspective: Environmental Science and Technology, v. 31, no. 8, pages 2229-2236.

Supplemental_Information:

REFERENCE: 1998, A national look at nitrate contamination of groundwater: Water conditioning and purification, v. 39, no. 12, pages 76-79. Available through the internet at URL: http://pubs.usgs.gov/fs/1996/fs-092-96/fs092-96.html

Supplemental_Information:

REFERENCE: Smith, R.A,. Schwartz, G.E., and Alexander, R.B., 1997, Regional interpretation of water-quality monitoring data: Water Resources Research, v. 33, no. 12 [in press].

Supplemental_Information:

REFERENCE: U.S. Bureau of the Census, 1991, 1990 Census of Population and Housing, Public Law 94-171 Data (United States): The Bureau, Washington D.C. (machine-readable files)

Supplemental_Information:

REFERENCE: 1995, 1992 Census of Agriculture: The Bureau, Washington, D.C. (machine-readable files).

Supplemental_Information:

REFERENCE: U.S. Soil Conservation Service, 1994a, State Soil Geographic (STATSGO) data base for the United States and Puerto Rico (CDROM): U.S. Department of Agriculture, Soil Conservation Service, Ft. Worth, Texas. Available through the internet at &http://www.ftw.nrcs.usda.gov/stat_data.html&

Supplemental_Information:

REFERENCE: 1994b, State Soil Geographic (STATSGO) data base--Data use information: Misc. Publication No. 1492, National Soil Survey Center, Lincoln, Nebraska. Available through the internet at &http://www.ftw.nrcs.usda.gov/stat_data.html&.

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 19970101

Ending_Date: 19971231

Currentness_Reference:Unknown

Status:

Progress: Complete

Maintenance_and_Update_Frequency: As needed

Spatial_Domain:

Description_of_Geographic_Extent:

Bounding_Coordinates:

West_Bounding_Coordinate: -129.49562

East_Bounding_Coordinate: -64.43927

North_Bounding_Coordinate: 48.633564

South_Bounding_Coordinate: 21.807903

Keywords:

Theme:

Theme_Keyword_Thesaurus: GCMD SCIENCE PARAMETERS

Theme_Keyword_Thesaurus: ANCILLARY KEYWORDS

Theme_Keyword_Thesaurus: ISO TOPIC CATEGORY

Theme_Keyword_Thesaurus: DATA SET LANGUAGE

Theme_Keyword: EARTH SCIENCE > HUMAN DIMENSIONS > ENVIRONMENTAL GOVERNANCE/MANAGEMENT > WATER MANAGEMENT

Theme_Keyword: EARTH SCIENCE > TERRESTRIAL HYDROSPHERE > GROUND WATER

Theme_Keyword: EARTH SCIENCE > TERRESTRIAL HYDROSPHERE > WATER QUALITY/WATER CHEMISTRY > NITROGEN COMPOUNDS

Theme_Keyword: EARTH SCIENCE > TERRESTRIAL HYDROSPHERE > WATER QUALITY/WATER CHEMISTRY > NUTRIENTS

Theme_Keyword: EARTH SCIENCE > HUMAN DIMENSIONS > ENVIRONMENTAL GOVERNANCE/MANAGEMENT > ENVIRONMENTAL ASSESSMENTS

Theme_Keyword: Gis

Theme_Keyword: Ground Water Contamination

Theme_Keyword: Ground Water Pollution

Theme_Keyword: Ground Water Vulnerability

Theme_Keyword: National Water-quality Assessment

Theme_Keyword: Nawqa

Theme_Keyword: Conservation

Theme_Keyword: ENVIRONMENT

Theme_Keyword: GEOSCIENTIFIC INFORMATION

Theme_Keyword: INLAND WATERS

Theme_Keyword: ENGLISH

Place:

Place_Keyword_Thesaurus: GCMD

Place_Keyword: CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA

Access_Constraints: None

Use_Constraints:

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Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

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Logical_Consistency_Report:

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Completeness_Report:

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Lineage:

Process_Step:

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Horizontal_Coordinate_System_Definition:

Geographic:

Latitude_Resolution: 1.0

Longitude_Resolution: 1.0

Geographic_Coordinate_Units: Decimal degrees

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: DOI/USGS/WRD/GIS > Water Resources Maps and GIS Information, Water Resources Division, U.S. Geological Survey, U.S. Department of the Interior

Contact_Person: KERRIE J. HITT

Contact_Position: DATA CENTER CONTACT

Contact_Address:

Address_Type: Mailing and Physical Address

Address: U.S. Geological Survey

Address: 12201 Sunrise Valley Drive

City: Reston

State_or_Province: VA

Postal_Code: 20192

Country: USA

Contact_Voice_Telephone: 703-648-6854

Contact_Electronic_Mail_Address: kjhitt@usgs.gov

Resource_Description: USGS_gwrisk

Distribution_Liability:

Not Available

Standard_Order_Process:

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Format_Name: ArcInfo export format

Transfer_Size: 2344333 bytes

Transfer_Size: 688538 bytes

Digital_Transfer_Option:

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http://water.usgs.gov/lookup/getgislist

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DATA CENTER URL

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Fees: No Fees

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Metadata_Reference_Information:

Metadata_Date:

Metadata_Review_Date: 20110701

Metadata_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: KERRIE J. HITT

Contact_Position: DIF AUTHOR

Contact_Address:

Address_Type: Mailing and Physical Address

Address: U.S. Geological Survey

Address: 12201 Sunrise Valley Drive

City: Reston

State_or_Province: VA

Postal_Code: 20192

Country: USA

Contact_Voice_Telephone: 703-648-6854

Contact_Electronic_Mail_Address: kjhitt@usgs.gov

Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Time_Convention: local time