County: July flood a 500-year event | RecordCourier.com

County: July flood a 500-year event

A woman takes a picture of the flooding on Kayne Street in between Johnson Lane and Stephanie Way during July 8 flooding.

Douglas County officials are calling the July floods in Johnson Lane a once in 500-year event.

County Manager Jim Nichols said the floods, which struck on July 8-10, included a 500-year, one-hour storm that dropped 1.12 inches of rain in the mountains above Johnson Lane.

Nichols said the drainage systems in northern Carson Valley aren't designed to handle that much water.

"County drainage systems are generally sized for the 25-year 24-hour storm, which is a long, gentle rainfall with an intensity of about .1-inches per hour," he said. "Last year's flood event was a 100-year, two-hour rain event which delivered about .6-inches of rainfall an hour. These events are 6-12 times more powerful than what the drainage system in Johnson Lane is equipped to handle."

A 500-year-flood means that there is 1 chance in 500 during any given year that a large flood will occur.

County commissioners are scheduled to hear a report from Emergency Manager Tod Carlini at their Thursday meeting.

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A flooding workshop is scheduled 3:30-7 p.m. Thursday at the CVIC Hall in Minden.

County commissioners are not expected to attend the workshop because their meeting will continue into the afternoon, public information officer Melissa Blosser said Monday.

A second consecutive year of flooding in northern Carson Valley resulted in county commissioners declaring a disaster on July 8.

Carlini told commissioners at that meeting that there appeared to be more water coming down the mountain, and more rocks.

Maintenance Operations Supervisor Chris Oakden told commissioners that all the work the county had done on Johnson Lane to recover from the floods of summer 2014 had been undone by these storms.

Northeastern Carson Valley suffered from three days of flooding in early July after a wet storm system brought rain to Western Nevada.

Minden received 1.14 inches of rain during the month, most of it in the second week, which made it the fifth wettest July on record.

Four days of rain saturated the Pine Nuts before water began pouring down the washes, closing East Valley Road, Johnson Lane and Stephanie Way.

University of Nevada Cooperative Extension hydrologist and long time Johnson Lane resident John Cobourn said that both Johnson Lane and Buckbrush washes were running high from the storm.

"The flood was coming down at Esaw and Stephanie and was contributing a lot of water that flows down Stephaine," he said. Buck Brush stayed in the channel. The drainage between them is less than a square mile, but it really cut loose along Esaw, doing quite a bit of damage along the houses."

He said the July 8 flood was one of the biggest ones he's seen in 25 years.

"There was a lot of hail mixed in with sediment," he said. "It came through as a wall of slush."

Cobourn said Esaw Street to Lindsey Lane is near the same area damaged last July in the Hot Springs Mountain flood.

"It's making people think," he said. "We have been talking with a small group of residents about trying to look for some solutions with the county and the Bureau of Land Management."

Cobourn said that a lot of residents along Esaw had water damage.

"They had three pieces of machinery pulling sediment out of one yard," he said.

IF YOU Go

There are two separate events in Minden on Thursday related to the July flooding. The first is a report to Douglas County commissioners shortly after their meeting begins at 1 p.m. Residents will have an opportunity to comment. A flood workshop is scheduled for 3-7 p.m. at the CVIC Hall where various county representatives will be available to discuss the flooding.