Marshes tend to have permanent open water, which can very in depth and temperature. Unlike swamps, they are not typically forested and have a range of submerged, emergent and semi-aquatic vegetation, usually herbaceous such as grass, sedges, rush and cattail species. Water tolerant shrubs such as sweet gale and hardhack often form part of the perimeter vegetation. Marshes may be fed and sustained by groundwater and or surface water and levels can fluctuate seasonally or for tidal marshes - daily. On the South Coast, marshes occur in a range of sizes, often supporting extensive cattail, bulrush and pond lily communities. A number of extensive marsh complexes are the result of sloughs - such as disconnected Fraser River floodplain channels, having reduced flow velocity allowing for marsh characteristics to form. Marshes support species of conservation concern such as Oregon Spotted Frog, Northern Red-legged Frog and Western Painted Turtle. On the South Coast a number of blue-listed marsh communities (Sitka sedge - Pacific water-parsley, common spike-rush Herbaceous Vegetation, common cattail Marsh) and one red-listed type - three-way sedge, can be found.