National Aquatic Resource Surveys (NARS) N/P Values for Lakes – National Lake Assessment

Metadata Updated: August 31, 2017

The National Aquatic Resource Survey (NARS) findings for nutrients in streams and lakes highlight that nutrient pollution is widespread across the United States and impacts biological communities. The NARS analysis examined the range of values for nutrients in least-disturbed sites in a NLA region [NLA regions are modified Level III ecoregions from Omernik (1987)] and used this distribution for nitrogen and phosphorus to separate sites into those having high, medium, or low concentrations of nutrients. Sites identified as "high" were worse (i.e., had higher nutrient concentrations) than 95% of the sites used to define least-disturbed condition. Similarly, the 75th percentile of the least-disturbed distribution was used to distinguish between sites in medium and low condition. This means that sites reported as being as "low" were as good as or better than 75% of the sites used to define least-disturbed condition. A relative risk analysis of the data from this survey found that nationally streams and lakes have more than two times greater risk of having degraded biological communities when nutrient concentrations are high than when they are low. For more information, please consult the National Lakes Assessment (NLA): Technical Appendix Report available online at: http://water.epa.gov/type/lakes/lakessurvey_index.cfm.

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Dates

Metadata Date August 30, 2017
Metadata Created Date August 31, 2017
Metadata Updated Date August 31, 2017
Reference Date(s) January 1, 2003 (publication)
Frequency Of Update notPlanned

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Harvested from Environmental Dataset Gateway FGDC CSDGM

Additional Metadata

Resource Type Dataset
Metadata Date August 30, 2017
Metadata Created Date August 31, 2017
Metadata Updated Date August 31, 2017
Reference Date(s) January 1, 2003 (publication)
Responsible Party U.S. Environmental Protection Agency (Point of Contact)
Contact Email
Access Constraints Use Constraints: For use at 1:250,000 or smaller scales, Access Constraints: None.
Bbox East Long -66.957107
Bbox North Lat 49.371733
Bbox South Lat 24.545216
Bbox West Long -124.762834
Coupled Resource
Frequency Of Update notPlanned
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Harvest Object Id 74ab6be4-26b5-42fb-b686-a9106aa2e3e7
Harvest Source Id d0d72986-7693-406b-b71d-840540909711
Harvest Source Title Environmental Dataset Gateway FGDC CSDGM
Licence https://edg.epa.gov/EPA_Data_License.htm
Licence Url https://edg.epa.gov/EPA_Data_License.htm
Metadata Language
Metadata Type geospatial
Progress completed
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True

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