Outflows from Milner Dam in south-central Idaho could resume temporarily by May 20, the U.S. Bureau of Reclamation said.
Reclamation on May 13 stopped Milner outflows, as it did last year, as part of efforts to manage the irrigation water supply in the Upper Snake River Basin.
The large American Falls and Palisades reservoirs upstream are vital to production agriculture in eastern and south-central Idaho.
Brian Stevens, water operations manager for the bureau’s Upper Snake Field Office in Heyburn, said American Falls is projected to fill by May 15.
“Milner flow is being taken to zero to make sure American Falls fills for the irrigation season,” he said May 13. “Within about the next seven days, Milner outflow could come back on, depending on diversions" for irrigation.
This resumption will be temporary.
“Current projections show Milner outflow, once it resumes, could last about a week,” Stevens said. “After that, Milner flow will be zero for approximately a month, until flood-control operations are complete upstream at Palisades Dam. Then, Milner flow will come back on for a few months.”
Palisades flood-control operations will tae place for their fourth consecutive year.
Milner Dam Inc., consisting of several irrigation districts, owns the dam, which is between Twin Falls and Burley on the Snake River.
Irrigation districts in the Twin Falls area divert water above the dam, which can impound up to 33,600 acre-feet in Milner Pool. Milner Dam outflows, which support hydroelectric power generation and other uses downstream, are heavily influenced by how much water is stored upstream at Minidoka Dam and American Falls Reservoir.
“We want to store as much as we can at Palisades and American Falls for irrigation use,” Stevens said.
After peak storage levels are established, water is released at Milner Dam as part of Reclamation’s flow-augmentation program to benefit fish downstream. That is expected in middle to late June.
“Reclamation is targeting to fill the Upper Snake reservoir system in June,” Stevens said.