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ARTICLE

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MapMaker: United States Wetlands

MapMaker: United States Wetlands

A wetland is a terrestrial place covered, sometimes seasonally, by shallow water or that has water-saturated soil. Explore more than 35 million wetland and deepwater habitats in the United States, Puerto Rico, Virgin Islands, Guam, and the major Northern Mariana Islands.

Grades

5 - 12+

Subjects

Geography, Human Geography, Physical Geography, Geographic Information Systems (GIS), Earth Science, Geology, Oceanography, Biology, Ecology, Conservation

Image

Map by National Geographic

Learning materials

A wetland is a place covered, sometimes seasonally or intermittently, by shallow water or that has water-saturated soil. Wetlands are important because they offer flood protection, improve water quality, prevent the erosion of shorelines and reduce storm damage. Additionally, wetlands are biodiverse and provide habitats for thousands of plant and wildlife species. Wetlands are important recreational areas and very productive ecosystems and provide humans with many critical ecosystem services. They are vital to fish nurseries and essential stopovers for migrating birds and other wildlife.

Human activities threaten or stress wetlands in three major categories: chemical, physical, and biological. Chemicals, such as oil spills, fertilizers, and pesticides, can be carried into wetland environments by runoff changing the water chemistry which can kill plants or animals. Building roads, dikes, levees, drainage ditches, canals, or filling in wetlands physically alters the landscape by draining the water from the area. This might be done to develop the land, use it for agriculture, or to control mosquito populations. Finally, invasive species and grazing pose a biological threat to wetlands. Invasive species can out-compete natives which can alter the food web forcing endemic or migrating species to find other food sources if they can. Grazing wetlands remove vegetation, compact the soil, and damage stream banks which reduces water quality.

This dataset is from the United States Fish and Wildlife Service’s (FWS) National Wetland Inventory. It contains more than 35 million wetland and deepwater habitats in the United States, Puerto Rico, Virgin Islands, Guam, and the major Northern Mariana Islands. The FWS defines a deepwater habitat as “permanently flooded lands lying below the deepwater boundary of wetlands.” This dataset is updated by the FWS twice a year with newly mapped wetland areas, so if you do not see one near you it may be added to this dataset in the future.

In this geospatial dataset, the FWS uses the Cowardian system to classify wetlands. This schema includes five systems (marine, estuarine, riverine, lacustrine, and palustrine) and numerous subsystems and classes defined in the map pop-ups or this FWS report.

  • Marine: this deepwater system includes the continental shelf and coastlines. All aspects of this habitat–which extends from the end of the continental shelf to the extreme high tide zone, the edge of an estuarine system, or where trees and shrubs begin–are subjected to waves, currents, and high salinities.
  • Estuarine: sometimes called an estuary, this deepwater habitat occurs where freshwater meets saltwater to form brackish conditions. The location of an estuarine wetland can be defined by where the water’s salinity is less than 0.5 parts per thousand.
  • Riverine: this system includes wetlands and deepwater located within a river or stream’s channel or floodplain. A riverine habitat excludes wetlands dominated by trees, shrubs, mosses, or lichens and those with salinities of 0.5 parts per thousand or more.
  • Lacustrine: a large (at least 2 hectares [20 acres]), water-dominated habitat with less than 30 percent vegetation cover. Lacustrine wetlands often occur next to lakes or dams.
  • Palustrine: also called a marsh, swamp, or bog, this system is defined by its freshwater and the presence of trees, shrubs, mosses, and lichens. This is probably what you imagine when you think of a wetland.

It is estimated that approximately 75% of wetlands in the lower 48 are privately owned, putting the management and protection of wetlands into the hands of the people living in the United States. Here is how you can help.

  1. If your home has a stream, plant a buffer strip of native plants to prevent erosion and minimize the runoff of pesticides or fertilizers.
  2. Use as few pesticides or fertilizers as you can! These chemicals harm wildlife, kill native plants, and pollute our water.
  3. Choose native plants for your home and remove invasive species that may alter the way your local wetland ecosystem functions.
  4. Stormwater and runoff flow into wetlands taking any pollution with it. Pick up trash and dispose of it properly and do not pour chemicals into storm drains to help keep them out of rivers, streams, lakes, and wetlands.
  5. Keep pets indoors unless they are supervised so they do not eat the local wildlife (or get eaten!) or binge on any tasty plants a wetland may need.
  6. Conserve water. Use only as much as you need, check regularly for leaks, and save rainwater for watering your plants or garden.
  7. Get involved with a group that works to educate others and protect your local wetlands. If you need to, start your own!
Media Credits

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GIS Specialist
Anita Palmer
Writer
Sarah Appleton, National Geographic Society, National Geographic Society
Last Updated

May 25, 2022

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