Shoal in rivers, streams, and lakes. A shoal–sandbar may seasonally separate a smaller body of water from the sea, such as: The term "bar" can apply to landform features spanning a considerable range in size, from a length of a few metres in a small stream to marine depositions stretching for hundreds of kilometers along a coastline, often called barrier islands. They are typically composed of sand, although they could be of any granular matter that the moving water has access to and is capable of shifting around (for example, soil, silt, gravel, cobble, shingle, or even boulders). The grain size
Gravel chub May and continuing into June. Adult gravel chubs have been spotted spawning by gathering on gravel bars in soft currents created by a rise in the waterline after hard rains. The gravel chub is considered a threatened species in many areas mostly due to the fact that it has a highly specific, clean habitat need. As of 1988 it was considered endangered in Kansas, under legal protection in Indiana and Wisconsin and considered a special concern in Kentucky, Minnesota and New York. Gravel chubs need constant mild currents with silt free riffles. Agriculture run-off is the biggest threat to this