BOISE—The 2015 irrigation season should be adequate for most farmers in Southwestern Idaho, but only if natural river flows hold up.
“I still think we’re OK. The wild card is the river flow,” said Greg Curtis, superintendent of Nampa & Meridian Irrigation District, the valley’s largest.
Water supply managers said most reservoirs in the region started the season with a decent amount of storage water. However, snowpack levels were well below normal and unusually warm temperatures in February and March caused the snow to melt much quicker than normal.
That resulted in an early bump in river flows, before irrigators need the water. The big question now is how far into the season those flows will hold up, Curtis said.
Most irrigation districts in the region typically get by on natural flow rights well into the summer before switching over to water they have stored in reservoirs.
If river flows drop below a certain level too early in the season, those districts would have to turn to stored water much sooner than normal and that could cause reservoir levels to get depleted quicker.
How the weather fares over the next several months will determine if Pioneer Irrigation District has to reduce deliveries to its 5,800 patrons later in the season, superintendent Mark Zirschky said in a news release.
“Spring rains would really help by delaying demands on the system, but ultimately we are going to have to rely on our patrons to be as conservative as possible in their water use to help make our storage water last as long as possible,” he said.
Boise Project Board of Control Manager Tim Page said the water supply outlook for the Treasure Valley is “marginally adequate.”
The project delivers water to five irrigation districts and 165,000 acres on the Boise River system.
BPBC usually supplies water until the first part of October but whether the project will be able to keep the water flowing beyond September this year depends on how river flows hold up, Page said.
Water from the project started filling canals on April 1 and irrigation deliveries should start going full-bore about April 15, Curtis said.
Snowpack in the Payette River basin is less than half of normal, but the system’s reservoirs are in good shape, said watermaster Ron Shurtleff.
There won’t be any surplus water this year, he said, “but we’re looking fine.”
The Weiser River basin is a different story. Although carryover in most reservoirs on the system was good, snowpack is only 10 percent of normal.
The Weiser system provides irrigation water for about 55,000 acres.
Those who own storage water rights will probably be OK this year, said watermaster Brandi Horton, but the bulk of the water users in the basin get their water rights from natural stream flow provided by snowpack.
“For those folks, this is going to be one of the toughest years we’ve had in a very long time,” she said.
Source: www.capitalpress.com