
Information on this page
has been adapted from the Streamkeepers Handbook and Modules
Different kinds of streambed material influence plant and animal life in a stream. This material ranges in size from "fines" like silt, sand, and clay, to large boulders and bedrock. Although variety in material size is desirable, a streambed comprised primarily of fine sediment is less stable than one comprised primarily of boulder, cobble, and gravel. Larger material also provides better quality fish and aquatic invertebrate habitat.
Size Categories of Streambed Material | |
Bedrock | Solid Slab of Rock |
Boulder | > 25 cm diameter |
Cobble | 5 - 25 cm diameter |
Gravel | 0.2 - 5 cm diameter |
Fines | 0.2 cm diameter |