Stream flows across the West are now running as low as they normally would in late summer, but autumn storms won’t be coming to the rescue anytime soon.
And neither did record rainfall in California last weekend.
With seasonal dry weather likely to continue over the next couple of months, experts say the area is facing extremely parched conditions barring an unlikely stretch of low temperatures and high precipitation.
“We’re expecting it to get worse. You’re going to see deterioration in the region,” said Dave Simeral, research meteorologist at the Western Regional Climate Center.
Given higher-than-normal temperatures over the past two months, streams and rivers are likely to heat up to the point of causing fish kills in some areas, he said.
Waterways should currently be receiving an infusion of cold water from melting snowpacks, but that snowfall was severely lacking last winter, Simeral said.
“You’re not getting that cool water being put into the system,” he said. “You saw a lot more rain than snow.”
Snowpacks melted up to 12 weeks earlier than normal in Oregon and rainfall was insufficient to support stream flows, said Scott Oviatt, the state’s snow survey supervisor for the USDA’s Natural Resources Conservation Service.
“It’s unprecedented, what we’ve been able to observe,” Oviatt said.
If the current trend continues, it’s likely that some streams will completely dry out over the summer, he said.
For agriculture, that has meant senior water rights holders have “called” water up to a month and a half earlier than average, effectively cutting off irrigation for junior water rights holders, according to the Oregon Water Resources Department.
Some growers are trying to direct water toward higher-value crops like onions and potatoes at the expense of irrigating their hay, said Oviatt.
“A lot of hard decisions are coming into play,” he said.
The problem isn’t limited to surface water, as groundwater levels are also depleted, he said.
Low soil moisture must be replenished with steady rains, as heavy but short-lived storms fail to fully penetrate the ground, Oviatt said.
“To build that back up, it will take significant and slow precipitation events,” he said.
Washington is facing a similar scenario, as 80 percent of its streams and rivers are below normal or at historic low flows, said Dan Partridge, communications manager for the Washington Department of Ecology’s water resources program.
The current situation is worse than in 2005, which was Washington’s last statewide drought, he said.
The potential for significant streams to run dry is “most certainly a possibility,” which raises concerns about fish passage and mortality, Partridge said.
In California, state wildlife managers have been conducting “rescues” in which they manually remove fish from shallow pools and move them to better habitats, said Jeanine Jones, interstate resources manager for the California Department of Water Resources.
Recent rainstorms that flooded Southern California haven’t provided much help in terms of irrigation, she said. “A lot of it ran off right away.”
With stream flows “way low,” farmers are expecting to idle roughly half a million of the state’s nine million irrigated acres, said Jones.
Roughly 75 percent of the precipitation in California occurs between November and March, so any eventual reprieve from the drought isn’t likely to come soon, she said.
“We’ve got a long ways to go before we see any real activity on that front,” she said.
Idaho is also dealing with low stream flows but farmers had anticipated even worse conditions earlier in the year, said Liz Cresto, hydrology section supervisor for the Idaho Water Resources Department.
Irrigators are worried about the low water carryover in reservoirs that will be available for 2016, but this year, spring rains delayed the need for stored water use, Cresto said.
“We’ve been able to stretch the season more,” she said.