This shapefile is shown on the poster “Total Phosphorus Regions for Lakes in the Northeastern United States”. The map provides a synoptic illustration of regional patterns and histograms on the poster show the variability of total phosphorus values within those regions. Total phosphorus was selected as an indicator of lake trophic condition because of its role in controlling the overall fertility of most lakes. The approach used for delineating phosphorus regions is similar to that used by Omernik et al. (1988) for the map of summer total phosphorus in lakes in Minnesota, Wisconsin, and Michigan. The lake phosphorus regions are based on phosphorus data from 2,893 lakes monitored throughout the region. Locations of study lakes are displayed on an inset map. Many of the 61 delineated lake regions include lakes with a wide range of phosphorus values. The apparent distinguishing characteristic of each region, compared to adjacent regions, is in the distribution of values, which is determined by, or associated with, that region's landscape characteristics, including physiography, land cover/land use, vegetation (both potential and existing), bedrock and surficial geology, and soil types. Each mapped region is coded with a four-digit number. The first two digits refer to the specific ecoregion (see Omernik,1987) that all or most of the lake phosphorus region occupies. Ecoregion #58 is the Northeastern Highlands; #59 is the Northeastern Coastal Zone; #60 is the Northern Appalachian Plateau; #61 is the Erie Drift Plain; and #62 is the North Central Appalachians. The last two digits identify the phosphorus regions within ecoregions. The shading on the map illustrates the estimated central tendency of the regional range of phosphorus values. The 2,893 lakes that yielded the data used to define phosphorus regions represent about 13% of the approximately 22,000 lakes, ponds, and reservoirs larger than 1 hectare found in the study area. These data were acquired from a variety of sources, including federal and state agencies, university researchers, and private corporations. Data were screened to include only upper limnetic, mid-lake water samples collected during the growing season, roughly mid-June to mid-September. Summer values were used for all states except Pennsylvania, which reports phosphorus as a yearly average, and Vermont, which collects spring total phosphorus values. The Vermont spring values were qualitatively adjusted for regionalization purposes, through a comparison of Vermont values with patterns of summer values in similar regions, with similar landscape associations, in adjacent states. Lake phosphorus regions were delineated on 1:250,000-scale maps. While spatial patterns of lake data are apparent at varying scales, this map scale has proven to be effective for analyzing regional patterns, particularly when interpreting associations with mapped information related to landscape characteristics. References: Omernik, J.M. 1987. Ecoregions of the conterminous United States. Annals of the association of American Geographers. 77(1):118-125. Map Scale 1:7,500,000. Omernik, J.M., D.P. Larsen, C.M. Rohm, and S.E. Clarke. 1988. Summer total phosphorus in lakes: A map of Minnesota, Wisconsin, and Michigan. Envir. Management 12(6):815-825. Map Scale 1:2,500,000. Comments and questions regarding total phosphorus regions should be addressed to Glenn Griffith, USGS, c/o US EPA., 200 SW 35th Street, Corvallis, OR 97333, (541)-754-4465, email:griffith.glenn@epa.gov Alternate: James Omernik, USGS, c/o US EPA, 200 SW 35th Street, Corvallis, OR 97333, (541)-754-4458, email:omernik.james@epa.gov
Lake phosphorus regions help managers and researchers understand the patterns of trophic condition.
Electronic versions of ecoregion maps and posters as well as other ecoregion resources are available at: http://www.epa.gov/wed/pages/ecoregions.htm. Phosphorus regions were digitized at 1:250,000 or smaller scales and are intended for large geographic extents (i.e. states, multiple counties, or river basins). Use for smaller areas, such as individual counties or a 1:24,000 scale map boundary, is not recommended.
http://www.epa.gov/nheerl/
200 S.W. 35th Street
Publication date
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Boundary | Coordinate |
---|---|
West | -80.524129 (longitude) |
East | -66.957805 (longitude) |
North | 47.454625 (latitude) |
South | 40.500028 (latitude) |
CLASS phos_ug_l (µg/l = micrograms/liter) 1 < 5 (no polygons, only on poster histograms) 2 = 5-9 3 = 10-14 4 = 15-19 5 = 20-24 6 = 25-29 7 = 30-50 8 > 50 9 = water
None.
shapefile name
US Environmental Protection Agency
Internal feature number.
Range | Value |
---|---|
Minimum | 0 |
Maximum | 146 |
ESRI
Feature geometry.
ESRI
Range of prevalent total phosphorus values in lakes.
Value | Definition |
---|---|
1 |
<5 (µg/l = micrograms/liter) |
Definition Source: USEPA |
Value | Definition |
---|---|
2 |
5-9 (µg/l = micrograms/liter) |
Definition Source: USEPA |
Value | Definition |
---|---|
3 |
10-14 (µg/l = micrograms/liter) |
Definition Source: USEPA |
Value | Definition |
---|---|
4 |
15-19 (µg/l = micrograms/liter) |
Definition Source: USEPA |
Value | Definition |
---|---|
5 |
20-24 (µg/l = micrograms/liter) |
Definition Source: USEPA |
Value | Definition |
---|---|
6 |
25-29 (µg/l = micrograms/liter) |
Definition Source: USEPA |
Value | Definition |
---|---|
7 |
30-50 (µg/l = micrograms/liter) |
Definition Source: USEPA |
Value | Definition |
---|---|
8 |
>50 (µg/l = micrograms/liter) |
Definition Source: USEPA |
USEPA
Length of feature
ESRI
Area of feature in internal units squared.
ESRI
micrograms per liter for classes
USEPA
Tests for integrity have not been performed.
Features represented have not been tested for completeness
Data were collected using methods that have unknown accuracy (EPA National Geospatial Data Policy [NGDP] Accuracy Tier 10). For more information, please see EPA's NGDP at http://epa.gov/geospatial/policies.html
1) U.S.G.S. 1:250,000 topographic maps are used to delineate the regions. The lines drawn are manually digitized to produce georeferenced electronic files.
2) Base maps are joined together and errors along the edges are resolved.
3) Topology is established and the maps are reviewed for accuracy, completeness, and conformity with the original lines. Corrections are made.
4) Attributes are added.
5) Coverage converted to geodatabase and shapefile.
6) metadata.
Downloadable Data
Although these data have been processed successfully on a computer system at the Environmental Protection Agency, no warranty expressed or implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. It is also strongly recommended that careful attention be paid to the contents of the metadata file associated with these data to evaluate data set limitations, restrictions or intended use. The U.S. Environmental Protection Agency shall not be held liable for improper or incorrect use of the data described and/or contained herein.
http://www.epa.gov/nheerl/
200 S.W. 35th Street
http://www.epa.gov/nheerl/
200 S.W. 35th Street