"So far, we're about 70% of average for the Boise Basin,” said NRCS hydrologist Ron Abramovich. "It's better in the East and little worse in the Wood River Basin."
February's snowpack is shy of 7 feet; that's 30 inches less than last year and with half the water content. But Hydrologists say that Idaho still has holdover water from last year and that means water users should have more than enough water this summer.
“What we've seen is the stream flows are still above average right now from last year's snowpack, and the reservoirs are in good shape across the state as well. So most irrigators across the state are going to have adequate irrigation supplies,” said. Abramovich.
The lack of precipitation in January and early February resulted in meager snowpacks across the state.
“The highest snow packs are along the State’s western and southern edges since they are affected by the major storms hitting the southwestern states,” said Abramovich. “That’s the El Nino weather pattern – where the southwest gets above average snowfall and the Pacific Northwest is dry.”
Outside of Ririe, the Willow Creek Basin’s snowpack averaged 72 percent of normal to start March. The Blackfoot Basin averaged 71 percent of normal, and snowpack in the Portneuf Range near Pocatello was just 61 percent of normal. The Owyhee Basin in southwest Idaho recorded the state’s poorest snowpack, at 34 percent of normal.
The bulk of Idaho’s water supply comes from high mountain snow packs. The majority of reservoir inflows come from snow packs above 6,000 in southern Idaho and above 4,500 feet in northern Idaho. Given the low snow packs, a runoff will be a little below normal across the state but shouldn't impact recreation or agriculture.
“In a short water year, they might go with a crop that wouldn't take the water demand, like a wheat or barley,” said Boise River Water Master Rex Barrie. “High water crops, like potatoes and sugar beets, and things like that, they can plan to plant for something like that because we know we're going to have an adequate supply.”
March and April are critical months because most reservoir systems are nearly full. If the spring is dry Abramovich says there’s enough snowpack to fill up Boise’s reservoir system. “We know we still have enough water to fill the reservoirs,” said Abramovich.
But if the spring is wet, water managers will have to make room for snowmelt, just like last year.“The reservoir operators will have to release more water,” said Abramovich.
“Because of the low precipitation amounts, streamflow forecasts decreased from February predictions,” said Abramovich. "Most reservoirs across the state are already storing above average amounts for March 1. But they're well below average streamflow predicted for this summer, irrigation demand will draw down reservoirs to their minimal storage levels by summer’s end and greatly increase the need for a good snow year in 2019.”
Abramovich says the Boise Basin reservoir system is already three fourths full and there are still two months to gain snow.