Weather, water supply dictate the fate of chinook runs

The fate of seasonal chinook depends on weather patterns and a limited supply of water
Pete Samarin, a state fish biologist, stands along what’s known as the “holy water” section of the Rogue River below Lost Creek Dam Thursday. Samarin is in charge of the recommendations for releasing Lost Creek Lake water for Rogue fishery enhancement.

TRAIL — With his hand on the Rogue River's largest water faucet, Pete Samarin may have to decide this summer which of this year's runs of chinook salmon live or die.

Samarin is the state fish biologist in charge of setting Lost Creek Lake water releases this summer to stave off drought-triggered disease outbreaks that once regularly killed Rogue chinook by the thousands but is now largely kept in check by reservoir releases.

Lost Creek Lake releases

Here are the draft planned releases of water from Lost Creek Lake to the Rogue River, measured in cubic feet per second.

Period Release

May 11-20 2,100 cfs

May 21-31 2,100 cfs

June 1-20 2,400 cfs

June 21-30 2,350 cfs

July 1-10 1,600 cfs

July 11-Aug. 10 1,450 cfs

Aug. 11-31 1,600 cfs

Sept. 1-10 1,500 cfs

Sept. 11-20 1,000 cfs

Sept. 21-Oct. 31 900 cfs

— Source: U.S. Army Corps of Engineers

Samarin's agency, the Oregon Department of Fish and Wildlife, has a plan to divvy up the stored water to save both spring chinook, and later the fall chinook, from losing out to disease. But if forecasts for a hot and dry summer prove true, there likely won't be enough water for both runs to escape warm lower Rogue waters and reach their upriver spawning grounds.

Then, Samarin would have to make a choice: Which chinook run gets the water it needs? The depressed wild spring chinook run or the robust fall chinook run?

"There's a real possibility that one of these races could see some losses — and that would be the fall chinook," Samarin says. "If we have to make a decision, it's to protect the spring chinook."

Regardless, one thing is clear: Without that stored water, at least the fall chinook run could face peril, as it did regularly before Lost Creek dam went online in 1977.

"Without it, you'd not really have any water at all," Samarin says. "We can at least buffer any sort of outbreak. In a drought year without the (reservoir), you could lose 70,000 chinook.

"Whatever happens, it's better than what historically happened," he says.

Historically, the problem for Rogue chinook has been a natural disease called columnaris.

Columnaris attacks the fish's gills and suffocates them, but it poses no threat to humans in contact with the water or those who eat sport-caught salmon.

It is highly infectious to chinook, particularly when lower Rogue temperatures eclipse 70 degrees, and was one of the main reasons why the Rogue's environmental factors favored spring chinook over fall chinook.

Spring chinook enter the Rogue from April through June, quickly migrating 145 miles upstream to reach the cool waters of the upper Rogue upstream of Shady Cove, where they spawn in late summer. They normally escape the hot summer flows that are common in August, when fall chinook migration peaks.

Prior to Lost Creek dam, summer flows regularly created columnaris outbreaks that kept fall chinook numbers down.

Lost Creek dam, however, changed everything.

The placement of the dam blocked wild spring chinook from one-third of its natural spawning habitat to where the vast majority now spawn in just 11 river miles, between Shady Cove and Cole Rivers Hatchery, the end of the migration line.

Also, the reservoir's capturing of the sun's heat in winter has altered the incubation timing of chinook eggs in the upper Rogue gravels, further reducing wild salmon production.

Conversely, summer reservoir releases keep the river artificially higher and cooler in August, allowing the all-wild fall chinook run to explode tenfold from pre-reservoir years. It also opens access to more than 300 miles of spawning habitat in the main-stem Rogue as well as chinook-friendly tributaries such as the Applegate and Illinois rivers and Bear Creek.

Now Rogue spring chinook are considered depressed, with this year's wild returns into the upper Rogue an estimated 12,000 adult fish. That's why chinook-management plans for the Rogue put spring chinook, particularly early-run spring chinook largely displaced by the dam, as the basin's top management priority.

With an estimated 100,000 wild adults returning to the Rogue this year, fall chinook is considered robust and columnaris now rarely comes into play on the Rogue.


That's largely because biologists over time have developed a systematic water-release strategy that treats Lost Creek Lake water like a savings account, spending that water when needed most, first in June for spring chinook and then in August and early September for fall chinook.

Drought years that include hot, late-spring weather can throw those plans off, triggering columnaris outbreaks like the one in 1992 that killed off nearly 70 percent of the spring chinook run and triggered an upper Rogue fishing closure to protect those that survived.

A 2001 outbreak killed less than 20 percent of the spring and fall chinook runs, and that was the last outbreak with measurable impacts on chinook returns, according to the ODFW.

Last year's relatively low water threatened a columnaris outbreak in August, but fall chinook side-stepped an outbreak in part because thick smoke from summer wildfires sheltered the river from the sun, Samarin says.

This year's conditions are not as bad as '92, but with a record-low May snowpack of just 26 percent of average and only 74 percent of normal precipitation, flows into Lost Creek Lake are forecast to be just 70 percent of average from May through September, according to the Natural Resources Conservation Service.

Long-range weather forecasts are not promising, says Julie Koeberle, an NRCS hydrologist in Portland.

"It's really looking like it's going to be a hot, dry summer," Koeberle says. "That's what all the indicators are pointing to."

In short, a columnaris incubator.

The dearth of runoff this summer means state water managers have just 120,000 acre-feet of water set aside in Lost Creek Lake to help migrating chinook. The state's draft water-release plan allocated 80,000 acre-feet for spring chinook and the remaining 40,000 acre-feet for fall chinook.

Normally, May conditions create enough flows into Lost Creek that water releases don't eclipse the inflows until June, Samarin says.

This year, a draw-drown expected to begin no later than May 21, Samarin says.

That means tapping into that 80,000 acre-feet of water would begin early, threatening to tap out before the end of June, when three-fourths of spring chinook have migrated out of the lower Rogue and away from a columnaris outbreak, Samarin says.

The ODFW's chinook management plans put spring chinook needs ahead, so Samarin may need to take water planned for release in August for fall chinook to help spring chinook survive in June.

"We have the competing conservation plans, but emphasis is given to the spring chinook," Samarin says.

That could put fall chinook in jeopardy, particularly if triple-digit heat hits at the wrong time.

"When you take into account environmental factors, it's getting to the point where it's more of a real possibility that we lose some fish."

Reach reporter Mark Freeman at 541-776-4470, or email at mfreeman@mailtribune.com.



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