What is a Wetland?

Inland Wetlands

Where are all the Wetlands?

Wetlands for the Future

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Riverine wetlands occur along streams, rivers, and irrigation canals throughout the United States. They are particularly noticeable in western states such as Idaho because they form ribbons of trees and shrubs in an otherwise arid landscape. You may have heard of these inland wetlands by their other name: riparian areas.

Healthy riverine wetlands play an essential role in maintaining healthy streams and rivers. They typically support dense vegetation of trees such as cottonwood and quaking aspen, shrubs such as mountain maple and red alder, and grasses. These plants help bind the soil of banks, protect the banks from erosion during floods, and trap additional sediment from floodwaters. The plants also provide habitat for birds, amphibians, reptiles, mammals, insects, and fish. For example, birds-from tiny warblers to majestic bald eagles-use riparian areas for cover from the weather and for breeding, resting, and foraging sites.

Riparian habitat represents only about one percent of land in the Intermountain West, but scientists estimate that as many as eighty percent of birds and other animals of the West depend on riparian habitats during all or part of their lives. Like other kinds of wetlands, riverine wetlands are at great risk from human activity.

Riverine wetlands benefit young salmon directly, by providing them with shelter during the start of their lives. Riparian areas continue to benefit salmon indirectly throughout their lives, by helping to keep streams and rivers cool and free of sediment. The wetland vegetation shades the pools along the bank, and it also traps sediments during floods and binds the banks to prevent erosion. Sediment-free water is essential to salmon. For example, salmon eggs and alevin (hatchlings) depend on ample flows of clean water through gravel to bring them air and food. Sediment can smother the eggs and young salmon, and rob them of food. Sediment can also trap young salmon upstream and prevent their migration to the ocean. Likewise, sediment can block adult salmon downstream and prevent their return to spawning sites.

The wetlands of estuaries, such as at the mouth of the Columbia River, also provide essential resting and feeding places for salmon. Young salmon spend at least a short time in these quiet waters before moving into the ocean; fall chinook salmon spend months there before beginning their adult journeys. Returning salmon also may rest briefly in the nutrient rich waters of the estuaries, consuming one last massive meal before they journey to their spawning grounds.

What is a Wetland? | Where are all the Wetlands?
Inland Wetlands | Wetlands for the Future | People and Wetlands |
Classroom Activities | Wetland Facts | Wetland Links |

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