This wetland community is characterized by the presence of swiftly moving, permanent water and usually a poorly developed floodplain.  The bottom sediments consist of gravel,  cobble, rubble, boulders, or bedrock.  Riffles and rapids are interspersed with pools along the length of the stream. There are no named soils in this community although, in large areas, some soil maps may list them as riverwash.

Great diversity exists in the fish and aquatic invertebrate faunna due to the abundance of oxygen, the variety of habitat types, and generally good water quality.

Water willow is one of the most common and abundant plants of gravel bars between pools, and in the finer soils within shallow water areas.

Other wetland vegetation is limited to a few species that can survive in the shallows or along the stream bank.

Some headwater streams in Illinois can be placed in this class.

*Used throughout the community descriptions to indicate the most commonly occurring code in Illinois.

Upper Perennial Stream