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This Month in Cal OES History: 1986 Floods

by on February 29, 2016

One of the most devastating floods in California was 30 years ago this month.

Thirteen deaths and 96 injuries were confirmed in the 1986 floods, and more than 50,000 people were evacuated from their communities.

The heaviest rainfall (17.60 inches) ever recorded in a 24-hour period in the Central Valley occurred at Four Trees in the Feather River Basin on Feb. 17, 1986. Calistoga received 29 inches of rain over 10 days.

Floodwaters ripped bridges from their foundations and caused levee breaks.

Snow levels ranged between 7,000-8,000 feet in the Sierras. About 15-20 feet of new snow was registered above 8,000 feet, while the Truckee Ranger Station recorded more than 17 inches of rain.

The nine-day storm raged throughout California accounting for half of the average rainfall for the year. Extensive flooding paralyzed most of the northern part of the state, including the worst flood to date in Napa and levee breaks along the Feather River in Olivehurst and Linda.

Flooding in the small San Joaquin County town of Thornton was caused by a levee break in the Mokelumne River. Lake Tahoe rose six inches alone in that span.

Nevada also was decimated by rainfall. Carson City absorbed nearly 10 inches of rain in nine days, and the Third Creek canyon above Incline was walloped by an avalanche estimated at 300 yards wide, snapping trees 200-feet high at their base.

Casinos had to sandbag their structures as floodwaters surrounded Reno. Mud and rock slides closed numerous roads in the Tahoe Basin.

Approximately 42,300 residences and businesses spread across Fallon and Lake Tahoe were without gas for more than a week after a 12-inch natural gas pipeline ruptured near Wadsworth due to the heavy flood pressure on the Truckee River.

Due to extreme flooding, new floodwalls were built for creeks in Sacramento and stronger levees were constructed on the American River. At the Folsom Dam, crews raised the dam wall and created a new spillway for water release control.

Flood concerns were raised this winter with projections of El Niño. While no extreme flooding has been reported, the Sierra snowpack was 94 percent of normal as of Monday and reservoirs throughout the state continued to slowly fill. Rainfall totals in several Northern California cities were at or near historic averages to date – San Jose, 87 percent; San Francisco, 87 percent; Eureka, 132 percent; Oakland, 76 percent; and Redding, 102 percent.

The majority of the state has had a relatively dry month of February, some with as much as two weeks without precipitation. The next chance of rain is expected to arrive sometime this week, possibly as early as Thursday.

From → Press Releases

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