Layer name Data Name Source Description Format
NHD Water Layer Streams USGS National Hydrography Database, medium resolution streams and other water features. Streaming WMS service from EPA Waters Services. Provides access to the medium resolution National Hydrography Dataset (NHD) stored in WATERS. This service is pre-projected in the Web Mercator projection. WMS
Per Cent Forest Canopy   USGS This layer (an NLCD product) is presented here as a reclassification into groupings or levels of %In this study, a strategy is developed for estimating tree canopy density at a spatial resolution of 30 m. This strategy is based on empirical relationships between tree canopy density and Landsat data, established using linear regression and regression tree techniques. Raster
Per Cent Impervious surface   USGS

This layer (an NLCD product) is presented here as a reclassification into groupings or levels of % impervious surface from the original raster data.  This is translated into a shapefile. The scale of 0 to 100% impervious was reclassed thus:
1 = 0-20%
2 = 20 – 60%
3 = 60 – 100%

Source: An approach for mapping large-area impervious surfaces: Synergistic use of Landsat 7 ETM+ and high spatial resolution imagery
Limin Yang*, Chengquan Huang, Collin G. Homer, Bruce K. Wylie and Michael J. Coan , Raytheon Corporation, U.S. Geological Survey EROS Data Center, Sioux Falls, SD 57198 USA

HIT Sediment  


Streaming WMS service from Michigan State Institute of Water Research

sediment - a 30-meter resolution raster dataset containing estimates for annual sediment loading for the selected 8-digit watershed as predicted by combining erosion estimates from RUSLE and delivery ratio estimates from SEDMOD.

HIT Erosion   MS - IWR

Streaming WMS service from Michigan State Institute of Water Research

erosion - a 30-meter resolution raster dataset containing estimates for annual erosion for the selected 8-digit watershed as predicted by RUSLE.


HUC 8, 10, 12 layer



Watershed outlines from EPA Waters streaming WMS service: Provides access to NRCS HUC2, HUC4, HUC6, HUC8, HUC10 and HUC12 polygons for the Watershed Boundary Dataset. This service is pre-projected in the Web Mercator projection.

CrEAM Layers


  EPA Region 5

CrEAM C1 Data Layer

The CrEam study created a set of preliminary data layers similar ot an index layer. We use it here as a surrogate to show how rankings might be created. After this study was finished, the EPA Science Advisory Board (SAB) evaluated the study and reported:

The SAB finds that:
• The CrEAM offers great promise as a regional screening level approach to identifying critical landscapes. The CrEAM, as presented, can be an appropriate regional tool for allocating internal EPA resources for site inspection activities, tracking general trends in the regional landscape condition, and reviewing grant proposals to the Agency. The CrEAM is also an appropriate framework to foster further communication and dialogue between other federal and state agencies on the use of regional and spatial data in environmental decision-making.
• EPA’s proposed uses of the CrEAM are not all fully supported by the science underlying the model. The CrEAM, as presented, is not reliable for use in regulatory processes such as issuing or reviewing air and/or water quality permits; use as a basis for federal or state agency determination in National Environmental Policy Act (NEPA) reviews; use as a basis for setting compliance, enforcement or cleanup actions; or for establishing reference context for ecological protection and restoration. Such uses could, however, be supported by later versions of the CrEAM.

CrEAM Ecological Diversity Area    

Ecological Diversity Data Sets
A comprehensive definition of biological diversity is “the variety and abundance of species, their genetic composition, and the communities, ecosystems, and landscapes in which they occur. It also refers to ecological structures, functions, and processes at all of these levels. Biological diversity occurs at spatial scales that range from local through regional to global.” (Coufal 1997)

The concepts and measures of species diversity have occasionally been extended to the community level, and community diversity has been investigated to characterize landscapes (Dale et al. 2000), (Chapin et al. 2000). However, indices of species and community diversity are labor and data intensive to measure. They usually require extensive field observations and data collection and consequently are used over small geographic spans.

Study coined the term “ecological diversity” as the term for our first criterion in order to emphasize that our intent was to estimate the relative diversities of populations (species), communities, and ecosystems

CrEAM Self Sustainability Area


EPA Region 5

CrEAM Data C2 Layer In this portion of the study, self sustainability was defined as the potential for an ecosystem to persist for 100 years, an arbitrary number that suggests a stable ecosystem, without external assistance (i.e., management). Self sustainability was viewed as being negatively impacted by two factors, landscape fragmentation and presence of chemical, physical, and biological stressors (Underwood 1989).


CrEam Biorarity Area

  EPA Region 5 RARITY Layer C3
Rarity is a combination of land cover and biota rarity. We take biota rarity to include both species rarity and the rarity of higher taxonomic units, thus, our analysis incorporates measures of the rarity of land cover, species, and taxa. Land cover rarity (C3.1) is a direct measure of the NLCD land cover rarity within Omernik ecoregions.
Calc. flowpath DEM delineated watershed   accumulated flow starting at catchment of 809 cells (10 meter cells) Raster
landuse DEM delineated watershed   NLCD 2001 landuse cut to 8-digit watershed with buffer Raster
8 -digit watershed outline project boundary    

complex of 8 digit watersheds,

Available at


Hydrologic Soils



SSURGO soil data. Processed to use the majority hydrologic soil type for each mapping unit. Open polygons in original data (mostly urban and disturbed soils) are assigned class D.

Available at