Changing snow and rain patterns challenge Idaho farmers and water managers

Anderson Ranch Dam as seen from the South Fork of the Boise River.

This story is the first in a pair about water and agriculture in Idaho. Coming soon: How long-term drought and pollution are affecting available water for Idaho’s growing ag industry

Story and Photos by Logan Finney

As intense flooding destroyed infrastructure in places like Yellowstone National Park and its neighboring communities in June, the heavy rains also refilled many of the region’s reservoirs that had dropped to historic lows earlier in the year.

This recharged water storage was not expected, according to ecohydrologist Alejandro Flores, director of the Lab for Ecohydrology Applications and Forecasting at Boise State University.

“A wintertime in which you don't get a lot of precipitation, you don't get a lot of that build up of snowpack in the mountains in the western U.S.,” Flores said. “You go into the melt season thinking that you're going to be behind the ball in terms of your water supply.”

For Idaho farmers, 2022’s “miracle spring” brought short-term good news – paired with long-term challenges presented by changing climate and precipitation patterns.

Little Camas Reservoir, seen from the crest of its earthfill dam.

A Dry Winter and A Spring Miracle

After a few heavy snowfalls last December, Idaho saw several record dry months in the first quarter of 2022. That lack of overall snowpack in the mountains concerned water managers and irrigators, said Paul Arrington, executive director of the Idaho Water Users Association. The association includes the canal system operators who serve as a bridge between the farmers who need water for irrigating their crops and the water managers who operate Idaho’s dams and reservoirs.

“The way we fill our reservoir system is snow melting in the mountains, into the streams and creeks and rivers,” Arrington said. “It just created a huge hole.”

After low winter snow, the sudden downpours in spring and early summer that caused destructive flooding in parts of the country essentially “filled the hole” in Idaho’s water supply.

Climate scientists are dubbing the phenomenon of intense drought early in the year followed by sudden heavy rains a “miracle spring.” 

“You went into the spring months just dreading what was going to happen because it was such a horrible (dry) winter, and then spring somehow just salvages everything,” Arrington said.

The problem with a miracle is that it often comes when you least expect it.

“The water management agencies of the West are calibrating how they're operating the dams to the historical conditions,” Flores said. “All of a sudden, you get this influx of (precipitation) events, and now you might actually be in a condition where you have too much water.”

The Anderson Ranch Dam spillway.

Unpredictability for Farmers 

Flores and Arrington both said Idaho farmers are accustomed to dealing with drought conditions.

“Farmers are making plans. They're changing their crops from potatoes and things that take a lot of water to grains that take a lot less water. They’re shifting,” Arrington said. “Water managers are telling their patrons, ‘Expect to have short water supply and a short season.’”

Those conditions can change quickly, however, with the arrival of a miracle spring.

“This very wet spring basically delayed everything,” Arrington said. “It was colder than normal and wetter than normal, which meant your crops just weren't at the same point they usually were. They're trying to catch up, and we may see that the end of the season that normally ends in early October may go a little longer.”

While it’s too late to go back and revise plans for the growing season, Arrington said the majority of Idaho farmers won’t be devastated by the fluctuating precipitation this year.

“They've already made their plans, as far as whatever adjustments they made in their cropping patterns. That is what it is,” Arrington said. “But ultimately they're going to be able to get the crops they need to done, and they're going to be able to make it through the season.”

A flock of American white pelicans take off from Little Camas Reservoir.

A Changing Climate

The surprising weather patterns of 2022 are likely to become more common as Idaho’s climate continues to shift.

“One of the things about a warmer atmosphere – a warmer climate – is that a warmer atmosphere holds more water,” Flores said. “There's a growing body of work to suggest that climate change, in addition to being associated with extreme droughts, will also be associated with extreme flood events and extreme precipitation.”

In layman’s terms, “we're not necessarily getting less moisture now, it's just coming differently,” Arrington said. “It's anticipated that those changes will continue, so maybe we get less snow and more rain.”

He pointed to water system adaptations that are already underway, such as the raising of Anderson Ranch Dam, as scientists like Flores say additional difficult-to-predict “miracle springs” are likely in the decades ahead.

“When all of a sudden you have that much rain in such a short period of time, it makes it difficult to manage and to store everything, because the system is built to capture snowfall and melt off. That's the most efficient way that system manages itself,” Arrington said.

“When you have these kinds of rains, it's just different,” he said. “No one expects it to go back to the way that winters were 40 years ago, when you’d wake up to 20 feet of snow in your yard.”