Wetland Plant
Indicator Status
What OBL, FACW, FAC, FACU, and UPL mean, how the three hydrophytic-vegetation tests work, the 10 USACE wetland regions, and a searchable sample of common delineation species — all based on the 2022 NWPL (version 3.6).
This reference is provided for educational and field-planning purposes only. It is not regulatory advice and is not a substitute for the official National Wetland Plant List (NWPL) or for a wetland delineation performed by a qualified professional. Wetland indicator statuses are region-specific and are revised by the U.S. Army Corps of Engineers on a roughly two-year cycle; values shown here reflect commonly documented ratings from the 2022 NWPL (version 3.6) and may not be current for every region. For any jurisdictional determination, look up each species in the official NWPL tool for the applicable Corps region, follow the 1987 Corps of Engineers Wetlands Delineation Manual and the relevant Regional Supplement, and rely on the determination of a qualified delineator and the controlling Corps district.
The five indicator statuses
Every species on the NWPL carries a wetland indicator status for each region. Species rated OBL, FACW, or FAC count as hydrophytic in the Corps' vegetation tests.
Almost always occur in wetlands.
Estimated probability >99% occurrence in wetlands under natural conditions.
Usually occur in wetlands, but may occur in non-wetlands.
Usually occurs in wetlands (est. probability 67–99%), occasionally in non-wetlands.
Occur in wetlands and non-wetlands.
Equally likely in wetlands and non-wetlands (est. probability 34–66%).
Usually occur in non-wetlands, but may occur in wetlands.
Usually occurs in non-wetlands (est. probability 67–99%), occasionally in wetlands.
Almost never occur in wetlands.
Almost always occurs in non-wetlands (est. probability >99%).
The historical NI (No Indicator) and NA (No Agreement) categories were removed in the 2012 NWPL update, as were the legacy +/- modifiers.
The three hydrophytic-vegetation tests
Under the 1987 Corps Manual and its Regional Supplements, vegetation is hydrophytic if it passes any one of these, applied in order:
1Rapid Test for Hydrophytic Vegetation
Vegetation is hydrophytic if all dominant species across all strata are rated OBL or FACW (and clearly so on inspection). A quick screen — when it clearly passes, the Dominance Test and Prevalence Index need not be calculated.
All dominants OBL or FACW.
2Dominance Test
Vegetation is hydrophytic if more than 50% of the dominant plant species (across all strata combined) are rated OBL, FACW, or FAC. Dominant species are selected within each stratum by the 50/20 rule.
>50% of dominants are OBL, FACW, or FAC.
50/20 Rule: Within each stratum, rank species by absolute percent cover (descending). Dominants are the most abundant species that cumulatively account for more than 50% of total cover in that stratum, plus any additional species that individually account for at least 20% of total cover in that stratum.
3Prevalence Index
Vegetation is hydrophytic if the Prevalence Index — a cover-weighted average of all species' indicator statuses across all strata — is 3.0 or less.
Prevalence Index ≤ 3.0.
PI = (1·A_OBL + 2·A_FACW + 3·A_FAC + 4·A_FACU + 5·A_UPL) / (A_OBL + A_FACW + A_FAC + A_FACU + A_UPL), where A_x = summed absolute percent cover of all species in status x. Weights: OBL=1, FACW=2, FAC=3, FACU=4, UPL=5.
Common species & their indicator status
A curated sample of 38 commonly-encountered delineation species. Search by name or filter by status. Statuses are region-specific — always confirm in the official NWPL tool for your Corps region.
Showing 38 of 38 sample species.
| Common name | Scientific name | Status |
|---|---|---|
| Broadleaf cattail | Typha latifolia | OBL |
| Bald cypress | Taxodium distichum | OBL |
| Common buttonbush | Cephalanthus occidentalis | OBL |
| American white waterlily | Nymphaea odorata | OBL |
| Broadleaf arrowhead / duck potato | Sagittaria latifolia | OBL |
| Softstem bulrush | Schoenoplectus tabernaemontani | OBL |
| Green arrow arum | Peltandra virginica | OBL |
| Common spikerush | Eleocharis palustris | OBL |
| Smooth cordgrass | Spartina alterniflora | OBL |
| Upright / tussock sedge | Carex stricta | OBL |
| Poison sumac Despite being a sumac, poison sumac is an OBL wetland species — a common field surprise. | Toxicodendron vernix | OBL |
| Silver maple | Acer saccharinum | FACW |
| Black willow Legacy lists may show 'FACW+'; the +/- modifiers were discontinued in the 2012 NWPL. | Salix nigra | FACW |
| Green ash | Fraxinus pennsylvanica | FACW |
| Red-osier dogwood | Cornus sericea | FACW |
| Jewelweed / spotted touch-me-not | Impatiens capensis | FACW |
| Sensitive fern | Onoclea sensibilis | FACW |
| Common reed | Phragmites australis | FACW |
| American sycamore | Platanus occidentalis | FACW |
| River birch | Betula nigra | FACW |
| Common / soft rush Commonly FACW; confirm by region — subregional ratings exist. | Juncus effusus | FACW FACWNCNE FACWAGCP FACWWMVC |
| Swamp chestnut oak Documented region-dependent example: FAC in the Western Gulf Coastal Plain subregion, FACW elsewhere in AGCP (2022 NWPL). | Quercus michauxii | FACW FACAGCP (Western Gulf Coastal Plain subregion) FACWAGCP (rest of region) |
| Red maple Classic FAC species; rating is consistent across most eastern regions. | Acer rubrum | FAC |
| Sweetgum | Liquidambar styraciflua | FAC |
| Eastern poison ivy | Toxicodendron radicans | FAC |
| Black gum / black tupelo Often cited as FAC nationally; can rate FACW in some regions — verify by region. | Nyssa sylvatica | FAC |
| Boxelder Often FAC; some regions place it nearer FACU — verify by region. | Acer negundo | FAC |
| Loblolly pine* Frequently FAC in southeastern regions but the rating varies — verify by region in the official tool. | Pinus taeda | FAC |
| Northern red oak | Quercus rubra | FACU |
| Allegheny blackberry | Rubus allegheniensis | FACU |
| Eastern white pine | Pinus strobus | FACU |
| Canada goldenrod | Solidago canadensis | FACU |
| Virginia creeper | Parthenocissus quinquefolia | FACU |
| White oak | Quercus alba | FACU |
| Black locust | Robinia pseudoacacia | FACU |
| Shortleaf pine* Often FACU/UPL depending on region — verify; included to illustrate the dry end. | Pinus echinata | FACU |
| Farkleberry / sparkleberry* Typically a dry-site species; verify the exact UPL/FACU rating by region. | Vaccinium arboreum | UPL |
| Virginia pine* Generally an upland pine; confirm UPL vs. unlisted by region. | Pinus virginiana | UPL |
* Status not firmly verified for every region — confirm in the official NWPL tool. This is a curated sample, not the full ~8,000-species list.
The 10 USACE wetland regions
Indicator statuses are assigned per region, and each region has its own Regional Supplement to the 1987 Corps Manual.
Northeastern and north-central U.S. — New England, Mid-Atlantic, and Great Lakes states north/east of the Midwest region.
ERDC/EL TR-12-1 — Regional SupplementAppalachian Mountains and Piedmont — from the Northeast south through the interior Carolinas and Georgia.
ERDC/EL TR-12-9 — Regional SupplementAtlantic and Gulf coastal plain — Eastern Seaboard lowlands and the Gulf Coast (incl. the Western Gulf Coastal Plain subregion).
ERDC/EL TR-10-20 — Regional SupplementUpper Midwest and Corn Belt — Ohio Valley and Great Lakes interior states.
ERDC/EL TR-10-16 — Regional SupplementGreat Plains — the Dakotas south through the Texas panhandle; prairie pothole and plains country.
ERDC/EL TR-10-1 — Regional SupplementArid and semi-arid Southwest and intermountain West — deserts and dry basins.
ERDC/EL TR-08-28 — Regional SupplementPacific Coast states and western mountain ranges — Cascades, Sierra Nevada, Pacific Northwest, and coastal California.
ERDC/EL TR-10-3 — Regional SupplementState of Hawaiʻi, Guam, the Commonwealth of the Northern Mariana Islands, and American Samoa.
ERDC/EL TR-13-3 — Regional SupplementWetland indicator status FAQ
What does FACW mean?
FACW stands for Facultative Wetland. On the U.S. Army Corps of Engineers National Wetland Plant List (NWPL), FACW species usually occur in wetlands but may occur in non-wetlands (classically, an estimated 67–99% probability of occurring in a wetland). FACW counts as a hydrophytic (wetland) indicator in the Corps' dominance and rapid tests.
What is the prevalence index?
The Prevalence Index is a cover-weighted average of the wetland indicator statuses of all plant species at a sample point. Each status is weighted OBL=1, FACW=2, FAC=3, FACU=4, UPL=5; you multiply each status's total percent cover by its weight, sum those, and divide by total cover. If the resulting index is 3.0 or less, the vegetation passes as hydrophytic. It is one of the three primary hydrophytic-vegetation indicators in the Corps Regional Supplements, typically used when the Dominance Test is inconclusive.
How do you determine hydrophytic vegetation?
Under the 1987 Corps Manual and its Regional Supplements, vegetation is hydrophytic if it passes any one of three tests, applied in order: (1) the Rapid Test — all dominant species are OBL or FACW; (2) the Dominance Test — more than 50% of dominant species (selected by the 50/20 rule) are OBL, FACW, or FAC; or (3) the Prevalence Index — a cover-weighted index of 3.0 or less. Atypical or 'problematic' situations have additional indicators, such as morphological adaptations.
What is the National Wetland Plant List?
The National Wetland Plant List (NWPL) is the official U.S. Army Corps of Engineers list that assigns each of roughly 8,000+ plant species a wetland indicator status (OBL, FACW, FAC, FACU, or UPL) for each of 10 wetland regions. It is administered by USACE with the EPA, U.S. Fish and Wildlife Service, and USDA-NRCS, and is the reference used to evaluate the hydrophytic-vegetation factor in Clean Water Act wetland delineations and Food Security Act determinations.
How often does the NWPL update?
The NWPL is on a two-year update cycle. Updates incorporate new species records, taxonomic changes, and rating revisions, with proposed changes published for public comment before being finalized. The current effective version is the 2022 NWPL (version 3.6), which became legally effective on February 13, 2024. Because ratings can change and are region-specific, always confirm a species' status in the official NWPL lookup tool.
Run wetland delineations in the field
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