WHITE CITY — By Rogue River Valley Irrigation District standards, the Yankee Creek flume is something of a youngster compared with much of the rest of the upper reaches of the district's Hopkins Canal.

Yet it's crumbling, leaks like a sieve and stands high enough above Yankee Creek to make lawyers take notice.

"It was built in 1955 with a 50-year life span," district Manager Brian Hampson says."It's run its course."

The flume is set to be replaced by underground pressurized pipe as part of an irrigation-improvement project that will make life easier for district patrons in the upper canal system and better for wild salmon in nearby Little Butte Creek.

The district plans to replace the Yankee Creek flume and other flumes with siphons and swap out 3.3 miles of its leaky, earthen canal with pipes that will save enough water to help the federal Bureau of Reclamation make good on some of its wild-salmon protection requirements here.

The district has a $3.6 million bureau grant to build and bury the first 1.2 miles of the 48-inch pipe, and the district is seeking grants to finish the final 2.1 miles at a cost of about $3 million more — less than the first phase because of no siphons, Hampson says.

When completed, it will fully replace the more than 100-year-old canal portion between its Bradshaw Drop diversion and Antelope Creek, all above Agate Lake — and at no added cost to its more than 900 patrons, Hampson says.

The upgrade is estimated to save 450 acre-feet of water that will be kept in Fish Lake, Hampson says. Most of that will be released into Little Butte Creek to boost June flows as required by a federal agreement that keeps the district and others here in business without doing undue harm to wild coho salmon, which are protected as threatened under the federal Endangered Species Act.

More water in Little Butte Creek would mean incremental gains in rearing habitat, cooler temperatures that coho and other salmon need in the summer and more assistance to out-migrating smolts, biologists say.

"No one's going to complain about extra water," says Pete Samarin, a biologist with the Oregon Department of Fish and Wildlife. "It's the age-old adage — fish need water.

"That will be nice if they put it in-stream," Samarin says. "We'll watch the gauge."

Many people, including salmon advocates, will be watching Little Butte Creek's gauges to ensure the bureau and the three districts it serves here follow a 2012 biological opinion by NOAA-Fisheries detailing how the irrigation districts should operate without illegally harming threatened wild coho. They include providing minimum summer stream flows in Little Butte and Bear creeks, two main conveyances of bureau water that are also home to spawning and rearing wild coho.

That report also called for specific improvements to in-stream habitat, making some diversions more fish-friendly, and controlling how abruptly some stream flows are altered for irrigation needs.

Biologists consider low and unreliable stream flows and a lack of complex in-stream habitat as major limiting factors in coho survival within the Bear Creek Basin.

The district on Monday chose OBEC Consulting Engineers, which has an office in Medford, to handle engineering and design, Hampson says. He hopes to begin the first phase of construction as soon as the upcoming irrigation season ends in the fall, he says.

The project also will serve as a demonstration for the WISE Project, an ambitious, long-term plan to pipe and pressurize irrigation canals to better deliver and conserve water throughout Jackson County and provide better habitat for wild salmon.

"It touches all the different aspects WISE is trying to get at," says Manager Steve Mason of WISE, which stands for Water for Irrigation, Streams and the Economy.

"It's something we can point to and say this is what we're trying to do, but on a much larger scale," Mason says.

The Talent Irrigation District is in the midst of a similar piping of a canal along the outskirts of Ashland that is also funded by the bureau, and its improved delivery efficiency will provide more in-stream water for Bear Creek salmon.

That project, however, is not using pressurized piping, so it can't be added to WISE should the option arise sometime in the future.

— Reach Mail Tribune reporter Mark Freeman at 541-776-4470 or mfreeman@mailtribune.com. Follow him on Twitter at www.twitter.com/MTwriterFreeman.