Cloud-optimized versions of Global terrestrial ecoregions from the World Wildlife Fund (WWF), based on the landmark Olson et al. (2001) classification. The dataset delineates 847 ecoregions grouped into 14 biomes and 9 biogeographic realms. Each ecoregion represents a distinct community of plants and animals sharing evolutionary history.
5,896 polygons · EPSG:4326 · H3 native resolution 8 (parent 0) · license: public domain (US federal work, 17 U.S.C. § 105 — see https://edg.epa.gov/EPA_Data_License.htm)
US EPA Ecoregions of the United States, Level IV, from the Omernik & Griffith framework — the US-native ecoregion standard, nested inside the North American (CEC) Level I/II tiers. 5,896 polygons. Covers the conterminous United States only (5,896 polygons, from EPA's us_eco_l4). Alaska is absent because EPA publishes no Level IV subdivision for Alaska — this is an upstream limit, not a processing shortcut. For Alaska at the finest available Omernik tier use the Level III collection (epa-ecoregions-l3), which does include Alaska. Hawaii, Puerto Rico and the territories are outside the Omernik framework entirely.
Every polygon carries the FULL hierarchy as attributes (NA_L1CODE/NAME, NA_L2CODE/NAME, US_L3CODE/NAME, US_L4CODE/NAME), so Levels I and II require no separate dataset — group this layer by the level you want. Distinct classes present: 10 Level I, 20 Level II, 85 Level III, 967 Level IV.
Delivered as GeoParquet for analysis, PMTiles for web mapping, and H3 hexagonal parquet at native resolution 8 (parent resolution 0) for spatial joins and aggregation.
Reprojected from the source Albers equal-area projections to EPSG:4326 with GDAL during preprocessing; geometry is otherwise unmodified. Attribute spelling and letter-case are verbatim from EPA — note that Level I/II names are ALL-CAPS while Level III/IV names are Title Case.
Group by an identifier column rather than a name column. The identifier columns are internally consistent, but a few of EPA's own names carry more than one spelling for the same unit, so grouping by the name splits that unit in two. Measured in this release:
Provenance. EPA publishes these files without a version label and overwrites them in place, and the previous download host has already stopped serving them, so the copy staged in this bucket is the durable record of what was ingested, retrieved 2026-08-27:
Counting: one row is one polygon, not one ecoregion. The 5,896 polygons make up 967 Level IV ecoregions, 483 of which are split into several separate polygons.
STAC: https://s3-west.nrp-nautilus.io/public-ecoregion/epa-ecoregions-l4/stac-collection.json
The source-layer is epa-ecoregions-l4. It is the last path segment of the dataset name, NOT the
EPA shapefile layer name (us_eco_l4_no_st). Using anything else renders a blank map — this is
the single most common mistake.
Note the Level I / Level II names are ALL-CAPS in the source while Level III / Level IV
names are Title Case. Match the values exactly as enumerated in the STAC values arrays.
h8 is the catalog's universal join key, so this layer joins straight to any other
res-8-carrying hex asset.
⚠️ Never SUM(Shape_Area) or SUM(Shape_Leng) on the hex asset. They are per-polygon
totals repeated on every cell the polygon covers. Dedup first
(SELECT DISTINCT _cng_fid, Shape_Area …), or derive area from the H3 footprint as above.
Source: EPA Office of Research and Development, Ecoregions of North America
(https://www.epa.gov/eco-research/ecoregions), staged to https://s3-west.nrp-nautilus.io/public-ecoregion/raw/.
Reprojected from the source Albers equal-area projections to EPSG:4326 with GDAL, then
converted, tiled and hexed with cng-datasets.
Build recipe: catalog/ecoregion/k8s/epa-ecoregions*/ in
boettiger-lab/data-workflows (issue #633).
Cite the framework as Omernik, J.M. (1987) Ecoregions of the conterminous United States, Annals of the Association of American Geographers 77(1):118-125, and Omernik, J.M. & Griffith, G.E. (2014) Ecoregions of the conterminous United States: evolution of a hierarchical spatial framework, Environmental Management 54(6):1249-1266.