Wetlands and critical habitat in California
Wetlands and protected habitat can shape what is possible on a piece of land. This guide explains the two federal maps Outpost shows, what they do and don’t mean, and how to check any California location.
In short
- The U.S. Fish & Wildlife Service’s National Wetlands Inventory (NWI) maps wetlands with a biological definition, not a legal one.
- Whether a wetland is regulated is decided by agencies such as the U.S. Army Corps of Engineers and California’s Water Boards, usually after a site delineation.
- Critical habitat is land designated under the Endangered Species Act. It mainly affects projects with federal funding, permits or other federal involvement.
- Outpost shows both, and checks the live NWI service for any point.
Screening only — not a legal or official determination. Verify with the issuing agency.
The National Wetlands Inventory
NWI maps wetlands and deepwater habitats nationwide. Outpost names the NWI types it finds: freshwater emergent wetland, freshwater forested/shrub wetland, freshwater pond, lake, riverine, estuarine and marine wetland, estuarine and marine deepwater, and other.
The Fish & Wildlife Service is clear about what NWI is not. It uses a biological definition of wetlands, so it doesn’t show whether wetlands covered by federal, state, tribal or local law are present, and it doesn’t define any agency’s jurisdiction. Before work that could affect wetlands, it recommends contacting your local Army Corps of Engineers regulatory office. California’s Water Boards also regulate wetlands and other waters of the state.
Critical habitat
When a species is listed under the Endangered Species Act, the Fish & Wildlife Service designates areas essential to its conservation as critical habitat where that is prudent and determinable.
- Federal agencies must not destroy or adversely modify it, and must consult the Service on actions they carry out, fund or authorize.
- It generally doesn’t affect private activities that need no federal funding, permit or other federal action.
- It doesn’t create a refuge or preserve, and it doesn’t give the government or the public access to private land.
Why it matters before building or buying
Grading, filling or building in or near wetlands can need permits, and a federal permit can also bring an Endangered Species Act consultation where critical habitat or listed species are involved. Projects can need biological surveys and extra environmental review under the California Environmental Quality Act (CEQA). Mapped wetlands can also reduce how much of a lot is practical to build on.
How to check a location on Outpost
- Find the location on the map: search an address or coordinates, or click the point.
- The scorecard’s wetlands row asks the live USFWS wetlands service about the point and its surroundings. It reports a wetland at the point and wetland types nearby (within roughly 800 to 1,000 feet).
- If the live service doesn’t answer in time, Outpost uses its own copy of the NWI map (about 30-meter detail) and marks the result as approximate.
- The biological row lists species whose final critical habitat, designated by the U.S. Fish & Wildlife Service, covers the point.
- To see the maps, turn on the Wetlands (NWI) and Critical Habitat layers in the sidebar.
- Freshwater emergent
- Freshwater forested / shrub
- Estuarine and marine wetland
- Estuarine and marine deepwater
- Freshwater pond
- Riverine
- Lake
- Other
What Outpost can’t tell you
- Whether a wetland is regulated, or where its legal boundary runs. That takes a wetland delineation and the agencies’ confirmation.
- Wetlands that NWI hasn’t mapped. Small or recently changed wetlands can be missing.
- Proposed critical habitat, and critical habitat designated by NOAA Fisheries for salmon, steelhead and other marine and anadromous species. Check NOAA Fisheries’ critical habitat maps for those.
- Whether a protected species is actually present on a lot.
- State and local rules, such as county grading ordinances.
Common questions
Is the NWI map a legal wetland boundary?
No. The Fish & Wildlife Service maps wetlands with a biological definition and says NWI doesn’t define any agency’s jurisdiction. The Army Corps of Engineers and the Water Boards decide what is regulated.
Does critical habitat on my land restrict what I can do?
Generally only when a project involves a federal agency, for example federal funding or a federal permit. Then the agency must consult the Fish & Wildlife Service.
How do I find out if my property has wetlands?
A qualified consultant can do a wetland delineation, which the regulating agencies then confirm. The NWI map and Outpost are a starting point for that conversation.
Does critical habitat mean the species lives on my lot?
Not necessarily. Critical habitat marks areas essential to a species’ conservation; it doesn’t say whether the species is on a particular lot.
Official sources
- U.S. Fish & Wildlife Service: National Wetlands Inventory
- U.S. Fish & Wildlife Service: Wetlands Mapper
- U.S. Fish & Wildlife Service: Critical habitat
- U.S. Fish & Wildlife Service ECOS: Critical habitat reports and maps
- NOAA Fisheries: Critical habitat (salmon, steelhead and marine species)
- California State Water Resources Control Board: Wetland and dredge or fill procedures
- U.S. Army Corps of Engineers: Regulatory program and permits
Related guides
- California groundwater basins and SGMA priority
What DWR’s SGMA basin priorities and critically overdrafted basins mean for wells and land in California, and how to see which basin a location is in.
- FEMA flood zones in California
What FEMA flood zones A, AE, V, X and D mean, when flood insurance is usually required, and how to check a California location for free.
- The California Coastal Zone
A section of the data sources page.