Flood Management

Clover DiversionFlooding is hazardous:

  • The force of moving water or waves can destroy a building.
  • Slow moving flood waters can knock people off their feet or float a car.
  • Even standing water can float a building, collapse basement walls, or buckle a concrete floor.
  • Water-soaked contents, such as carpeting, clothing, upholstered furniture, and mattresses may have to be thrown away after a flood.
  • Some items, such as photographs and heirlooms, may never be restored to their original condition.
  • Floodwaters are not clean: floods carry mud, farm chemicals, road oil, and other noxious substances that cause health hazards.
  • The impact of a flood, cleaning up, making repairs, and the personal losses can cause great stress to you, your family, and your finances.

Lakes & Streams

Flooding from streams and lakes have different characteristics. Visit our Hydrologic Information page for real-time stream flow and rainfall information plus stream flow forecasts.

Flooding in Lake County can be caused by streams, such as Scotts Creek or Putah Creek, and by lakes, such as Clear Lake or Blue Lakes. Flooding can also occur from poorly designed, constructed and/or maintained drainage facilities.

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.

Drainage Facilities

Flooding from local drainage facilities usually occurs quickly, is of limited extent and is short lived. Many of the drainage facilities in Lake County were installed many years ago, and are undersized and/or their condition has deteriorated from age, which may cause flooding. As funding permits, these facilities are being upgraded.

The County of Lake implements flood management activities to reduce flooding and reduce the adverse impacts of flooding in several ways. Most new facilities are reviewed by the County of Lake prior to construction and inspected to ensure they are designed properly. Flooding and other surface drainage problems can occur well away from a river or lake.

More Information

There are several ways you can determine your flood hazard. For a list of some things you can do to reduce flood hazards, visit the What Can You Do? page.

The County of Lake participates in the National Flood Insurance Program (NFIP). Information on flood insurance is available on the Flood Insurance page.

To reduce future flood damage, the county adopted regulations to reduce flood damage. These regulations are available on the Floodplain Management Regulations page.