Rodman Slough is a wetland that drains into Clear Lake in Lake County, California. It provides an important habitat for fish, amphibians, birds and other wildlife. It is fed by Scotts Creek and Middle Creek, which contribute about 70% of the sediment and nutrients that cause algae problems in Clear Lake. The slough is the remnant of a much larger area of wetlands and open water that extended from Tule Lake to the northeast through a wide area of land north and east of the present slough that was drained for farmland. Since 1978 there have been proposals to restore large parts of the former wetlands, and much of the funding has been approved, but progress has been slow.
Location
Rodman Slough is at an elevation of in Lake County, California. It flows south for into Clear Lake. The Scotts Creek and Middle Creek watersheds feed the slough. They supply about 70% of the sediment and nutrients delivered to Clear Lake, which cause the algae population to increase in the lake. During periods of heavy runoff the two creeks raise the level of the slough and the water moves at significant speed. Fine sediments are carried into Clear Lake, while coarse sediments are gradually filling in the slough. The high flows also erode the levees that protect adjacent reclaimed farmland.
Environment
Tule Lake is a seasonal lake that forms in the winter when Scotts Creek overflows its banks. It drains along Scotts Creek into Rodman Slough, The Tule Lake / Rodman Slough area is an important stopover for migratory songbirds and supports cover for many waterfowl and water birds. The Rodman Slough wetland areas and the oak woodlands that surround them have a large rookery of great blue heron (Ardea herodias), where migrating birds congregate in the fall. Other birds include American white pelican (Pelecanus erythrorhynchos), Canada goose (Branta canadensis), cormorant (Phalacrocoracidae), heron and egret (Ardeidae) and grebe (Podicipediformes). The slough is an important breeding and nursery area for fish species such as black bass (Micropterus), black crappie (Pomoxis nigromaculatus), white crappie (Pomoxis annularis) and catfish.
History
In the past the Scotts and Middle creeks flowed through Robinson Lake, also called Rodman Bay, before entering Clear Lake. Robinson Lake was a mosaic of shallow wetlands, meandering channels, riparian forest and open water. Bloody island was historically an upland island in Robinson Lake surrounded by a complex of seasonal and perennial wetland. The island was the site of the 1850 Bloody Island massacre in response to a Pomo revolt from slavery.
Between 1918 and 1933 farmers built levees in Robinson Lake and the area was drained for agriculture, leaving only the narrow Rodman Slough along the west of the former lake. The heavy earth-moving equipment used to "reclaim" about of wetland was one of the causes of a surge in sedimentation in Clear Lake after 1927.
In 1955 Congressman Hubert B. Scudder introduced a bill, which was authorized, for flood control works on Middle Creek at an estimated Federal cost of $1,110,000 and Non-Federal Cost of $790,000. At this time the community of Upper Lake was partially flooded three times a year, and almost all the town was flooded every ten years. In 1966 the United States Army Corps of Engineers (USACE) completed levees on the north side of Scotts Creek between Tule Lake and the mouth of Rodman Slough as part of the Middle Creek Flood Control project. The levees were intended to reduce the risk of flooding urban communities and agricultural areas.
In 1978 the Federal Emergency Management Agency (FEMA) determined that much of the area covered by the flood control project was in the 100-year floodplain of Clear Lake. Restoring the area to its natural state would reduce costs of maintaining old levees and drainage pumps, and reduce or eliminate the cost of fighting floods in high water years.
The levees are substandard and have settled, and are as little as above the lowest normal Clear Lake water level. In the past (1890) the Clear Lake water level has risen to above this lowest level. There is a very real risk that the levees will be submerged by the type of flood expected at least once every century. The Robinson Lake area was evacuated due to flood threats in 1983, 1986 and 1998. In 1995 Scotts Creek overtopped the levee, flooding parts of Highway 20.