Modesto rainfall actually normal; mountain snowpack is drought culprit

This could surprise you: Rainfall in Modesto over the past 12 months has been pretty much average.

Don’t feel foolish if you didn’t know that. It sure sounds suspicious, until you check data put on the Internet by the Modesto Irrigation District, which has been measuring rain in Modesto since 1888.

There it is, in black and white: 12.1 inches of rain since last summer – just shy of the 127-year annual average of 12.15 inches.

How can that be, if California is suffering one of the worst droughts on record?

The short answer: Rainfall in Modesto is not the same as snow in the mountains.

Much of that snowpack is captured in reservoirs that provide California with about 30 percent of its water, and most of the summer irrigation needed for valley farms.

And our mountains were not blessed with much snow last winter, or the three before.

In late March, snowpack in the Sierra Nevada stood at 12 percent of normal. Its water content was 5 percent of normal – the worst since 1950, the California Department of Water Resources said.

In April, news cameras captured Gov. Jerry Brown in a brown mountain meadow that should have been carpeted with several feet of snow. He used that backdrop to order mandatory cuts in water use for most Californians.

“When it comes time for irrigation, the farmer is relying on that snowpack,” said Tom Orvis, governmental affairs director at the Stanislaus County Farm Bureau. “You can say it was an average winter down here, but up there, it wasn’t, and that still determines the drought.”

Other factors contribute, such as ground so parched from multiple dry years that it soaks up whatever moisture does fall from the sky, keeping it from running into reservoirs. That’s partly why the Department of Water Resources’ climatologist estimated that California’s drought could not possibly end unless we get double what we’re used to in winter weather, and then some.

Scientists for years have warned that climate change isn’t just about warmer temperatures, but changes in storm patterns. We can expect less snow and more rain in years to come, they’ve been saying.

“That’s why people are trying to expand groundwater recharge areas along rivers, to capture those floods,” said Roger Bales, director of the Sierra Nevada Research Institute at UC Merced. “But some water agencies don’t have the resources to do much planning for it. A lot of water agencies are hurting out there.”

Meanwhile, some farmers on Stanislaus County’s west side and to the south are getting no river water, while the Modesto Irrigation District this year expects to deliver about a third the normal amount to farmers. Lawns are much more brown as people water less up and down the state. Cities and growers are pumping groundwater like crazy and some wells are going dry – despite what the numbers say about Modesto’s ample rainfall.

“You have to remember, it’s not just the rainfall; it’s the snowpack,” said MID spokeswoman Melissa Williams. “That’s the kicker.”

This story was originally published July 18, 2015 at 4:06 PM with the headline "Modesto rainfall actually normal; mountain snowpack is drought culprit."