Flooding in Lake County

Flooding in Lake County, California can be caused by streams, such as Scotts Creek or Putah Creek, and by lakes, such as Clear Lake or Blue Lakes. Flooding from streams and lakes have different characteristics. In mountainous terrain, flooding by creeks and small lakes occurs quickly in response to individual storms, and floodwaters recede quickly after the storm has ended. However, prolonged storm events can cause extended periods of flooding, and flat areas with poor drainage may also stay flooded for a long time. Floods can occur with little warning, as they did in January and March 1995, and in January 1997. Stream levels can increase over ten feet within hours of the storm's onset. Streams also carry debris, such as tree branches, that can cause property damage by slamming into structures, or cause a "log-jam," raising flood levels even higher. Bank erosion is common during flood events. Healthy vegetation on the bank of the stream, but not in the center, will help resist bank erosion and protect your property.

Due to its size, Clear Lake responds more slowly to storm events and rises to flood stage only after prolonged storms, as occurred in 1998. When this happens, Clear Lake's natural outlet, Cache Creek, is too small to allow floodwater to leave the lake as fast as it enters. Contrary to popular belief, the Clear Lake Dam does not cause Clear Lake to flood. The dam can actually release water much faster than Cache Creek can flow. It is the narrow, shallow Cache Creek channel that slows the release of water from Clear Lake during a flood.

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