Fresno-area agencies say they’re ready for El Niño storms

Fresno Irrigation District clears out a canal

A work crew from the Fresno Irrigation District trims tree and bushes along a canal south of the Tower District. (video: Eric Paul Zamora)
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A work crew from the Fresno Irrigation District trims tree and bushes along a canal south of the Tower District. (video: Eric Paul Zamora)

Fresno-area flood and water agencies say they’ve heard the forecast of a potential gully-washer of a winter but see no need to undertake any extra precautions to prepare for whatever El Niño is going to hurl at them.

The Fresno Metropolitan Flood Control District and the Fresno Irrigation District say they’re busy cleaning canals and drainage basins as they do every year to protect against flooding and hope the predicted storms will refill the area’s depleted lakes, basins and reservoirs. The city of Fresno says it’s cleaning out storm drains and preparing the drainage system for heavier-than-normal rainfall.

But Fresno County’s public works department says the possibility of rain is a blessing, and flooding is just a normal part of the winter.

“Everybody is hoping and praying for a lot of rain and snow,” said Ken Austin, emergency manager for the Fresno County Office of Emergency Services.

Rural communities have expressed concern about possible flooding, Austin said, so the office is looking to educate and prepare those in flood-prone areas.

Communities near the Kings and San Joaquin rivers or run-off creeks are the most at risk. Cities like Mendota, Firebaugh, Reedley, Huron and Coalinga are among those in flood paths, and residents should consult ready.gov or other disaster preparation websites to form a plan, Austin said.

“They might want to buy some sandbags to defend their property just in case,” Austin said.

Fresno County also has updated emergency plans with the American Red Cross and the public works departments of the local cities to form a coordinated response in case of flooding.

Above-average rain

The National Weather Service noted that Central California likely will receive above-average precipitation because of the 95 percent probability of an El Niño winter. Added moisture – especially during a major drought – often leads to flooding.

Meteorologist Jim Andersen with the weather service’s Hanford office explained why.

“When soil is baked in the sun, it changes its properties,” he said. “You would think dry soil would just soak up rain like a sponge, but water just sits on the top of these soil layers. When it’s flat, that isn’t too big of a deal. But if it happens at the top of a hill, that water has to go somewhere, and that’s when you get flash floods.”

Andersen said that a lack of vegetation also contributes to flooding and other problems. Plant roots help to hold the soil in place, and rain can cause this loose, dry soil to form into mudslides like the one that covered Interstate 5 near the Grapevine last week.

1/4 of an inchThe maximum amount of rainfall Fresno’s drainage system can accommodate per hour

Being prepared

Local agencies said Tuesday that they’re ready.

Fresno spokesman Mark Standriff said crews are cleaning out storm drains of debris and taking preventive maintenance steps. The city’s drainage system is ready to handle up to one-quarter of an inch of rain per hour, an amount which he said is a “once-every-two-years event.”

However, Standriff said that the drainage system was overwhelmed last year – twice. Should this happen again, the city’s “Storm SWAT Team,” a crew of 30 city employees, will be deployed to handle high-water issues. Flooding and drainage problems typically occur near underpasses or in low dips in terrain, like on Fort Washington Road near Woodward Park.

Standriff believes there is little chance of flooding during normal rainfall because the local drainage basins are quite low.

Everybody is hoping and praying for a lot of rain and snow.

Ken Austin, emergency manager for the Fresno County Office of Emergency Services

Water for farmers

Gary Serrato, general manager of the Fresno Irrigation District, said a major focus for his district will be capturing as much of this El Nino rainfall as possible for local growers and the depleted basins.

“We always reach out to our growers to see if they can take some of our water – at no cost, of course,” he said. Water can either be diverted onto farms using the district’s many canals or picked up and stored by farmers.

Many canals around town are empty, which Serrato said is normal for this time of year. The district uses the fall to clean out the debris and trash that people throw into the waterways, but it’s a losing battle.

“We start on the east side of Fresno and move our way through,” Serrato said. “But by the time we reach Highway 99, we have to turn back and start all over again because folks have dumped shopping carts, trash and tree prunings in them.”

Serrato said the district also is performing maintenance to prepare the canals for use by the Fresno Metropolitan Flood Control District.

Peter Sanchez, an engineer with Fresno Metropolitan, said his district controls around 160 of the 10-plus-acre ponding basins in and around Fresno. These basins are interconnected with other ponds and Fresno’s canal system to accept the runoff water from Fresno’s streets.

The basins are prepared to accept 6 inches of rainfall over a 10-day period, Sanchez said.

This would be a pretty major storm event for this area. The last time Fresno was anywhere close to this mark was nearly five years ago, when the area soaked up 7 inches of rain during a 17-day period in December 2010 and January 2011, Sanchez said.

11.5 inchesFresno’s average rainfall per water year, according to the National Weather Service in Hanford

To put this in perspective, Fresno’s average rainfall is about 11.5 inches per year. The city would have to get more than half of its annual rainfall in 10 days to cause any problems.

Meteorologist Modesto Vasquez with the National Weather Service in Hanford said this kind of downpour is a possibility if the right tropical storm system swept through the Valley, but it is “highly unlikely.”

If storm basins are overwhelmed, Sanchez said, water would be pumped into irrigation district canals. The irrigation and flood control districts, while separate entities, remain in constant contact with each other as well as the county and the cities of Fresno and Clovis to coordinate water levels.

Worst case

Both the flood control district’s and the irrigation district’s ponding basins absorb the melted snow from the Sierra Nevada and use it to recharge Fresno’s aquifer. They carefully maintain basin water levels to ensure the aquifer, which is as important as ever during the fourth year of a major drought, is healthy.

In the short term, the flood control district is prepared for the worst in November. Sanchez said this would be a 48-hour storm that delivers around 2 or 3 inches of rainfall.

“We take a look at the biggest storms on record for each month, and we try to prepare for that,” he said.

The district does not expect it will have to pump any water out of the basins in the near future.