National Wetlands Inventory

Part of United States mapping project.

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Much like the National Hydrography Dataset, The National Wetland Inventory (NWI) is a United States-wide w:en:hydrography dataset produced by the US Fish and Wildlife Service (USFWS). This dataset includes primarily wetland features like marsh, saltmarsh, bog, and swamp, but also natural water features: lakes and ponds. Conflicts should be avoided with the National Hydrography Dataset which also contains mapping of water features.

Getting the data

Data can be downloaded by statewide or HUC8 watershed extent (recommended) at the [Wetlands Mapper] or accessed through the [Data Download] page.

Attributes to OSM tags

The following has been borrowed from the Maryland/Wetlands Import page:

The attribution of the data is based on published Classification of Wetlands and Deepwater Habitats of the United States (2013, PDF) based on the de facto standard published by Cowardin et al in 1979. The Cowardin system is the federal standard for wetland classification used in the National Wetlands Inventory. The system uses an alphanumeric code to represent a wetlands characteristics. The codes are concatenated into a single string and are sometimes nested with other classifications. While useful for wetland inventory and research, the 500+ classification possibilities are outside of the scope of usefulness for the OpenStreetMap project (which has around ten wetland classifications in common use).

It is necessary to generalize the classifications for OSM. The United States Fish and Wildlife Service has a simple classification scheme that is based on the first few characters of the full Cowardin classification code, that this project will replicate.

The following table shows the generalized Cowardin wetland types and their OSM equivalent.

Wetland type	Map- Code	cowardin:description	wetland:description	OSM tags
Estuarine Deepwater	E1	Estuarine subtidal water and wetland	Open water estuary, bay, sound, open ocean	natural=water + tidal=yes
Marine Deepwater	M1	Marine subtidal water and wetland	Open water estuary, bay, sound, open ocean	natural=water + tidal=yes
Estuarine wetland	E2	Estuarine intertidal wetland	Vegetated and non-vegetated brackish and saltwater marsh, shrubs, beach, bar, shoal or flat	natural=wetland + wetland=saltmarsh
Marine wetland	M2	Marine intertidal wetland	Vegetated and non-vegetated brackish and saltwater marsh, shrubs, beach, bar, shoal or flat	natural=wetland + wetland=saltmarsh
Lakes	L	Lacustrine wetland and deepwater	Lake or reservoir basin	natural=water + water=lake
Freshwater Emergent wetland	PEM	Palustrine emergent	Herbaceous march, fen, swale and wet meadow	natural=wetland + wetland=marsh
Freshwater Shrub wetland	PSS	Palustrine shrub	Forested swamp or wetland shrub bog or wetland	natural=wetland + wetland=bog
Freshwater Forested wetland	PFO	Palustrine forested	Forested swamp or wetland shrub bog or wetland	natural=wetland + wetland=swamp
Freshwater pond	PUB	Palustrine unconsolidated bottom	Pond	natural=water + water=pond
Freshwater pond	PAB	Palustrine aquatic bed	Pond	natural=water + water=pond
Riverine	R	Riverine wetland and deepwater	River or stream channel	natural=water + water=pond

See also

• natural=wetland
• National Hydrography Dataset