AGNESS — The dark silhouettes of hundreds of Rogue River chinook salmon taking respite in the relatively cool waters of Hotel Riffle should make fishing guide Steve Beyerlin giddy.

Instead, the image is perhaps a grim foreshadowing of the future for the Rogue's fall chinook run.

Overstressed from the river's hot water, these salmon are taking refuge this week in Hotel Riffle because it is just downstream from the Rogue's confluence with the cooler-flowing Illinois River.

Their presence is a sign of how desperate these chinook are. And it's an indication to Beyerlin that these chinook likely won't survive to migrate upstream to the Rogue Valley.

"I just don't see how they're going to make it," Beyerlin says. "They won't be swimming forward. They'll be floating upside down and backwards."

That's what happens when the natural warm-water disease called columnaris breaks out in the lower Rogue during the fall chinook run, sometimes killing more than half of the fish before the survivors can reach Grants Pass.

A combination of relatively low flows and triple-digit air temperatures in the Rogue Valley have sent Rogue temperatures soaring here in Agness, a small river outpost that is 27 miles east of Gold Beach and just one-fourth of the salmon's trek toward Grants Pass.

A gauge at Agness reveals water temperatures above 77 degrees, enough in past years to trigger columnaris outbreaks.

So far, no dead chinook have been discovered, but state biologists have asked Mail Boat excursion jetboat drivers out of Gold Beach to keep their eyes open for the upside-down, backwards-floating salmon that Beyerlin fears.

"There's no question temperatures at the Agness gauge are up there," says Dan VanDyke, the Rogue District fish biologist for the Oregon Department of Fish and Wildlife. "With the low flows and hot temperatures, it certainly is possible that we could lose fish from columnaris this year."

VanDyke already has asked the Oregon Water Resources Department and the U.S. Army Corps of Engineers to keep water releases from Lost Creek Lake a bit higher than planned for July, during what is the end of the spring chinook migration.

Another chunk of Lost Creek Lake water already is set aside for release in August to curb a columnaris outbreak.

Beyerlin believes the chinook at Hotel Riffle won't make it that long.

"Barring a major rain event, they're toast," Beyerlin says.

Natural to the Rogue, columnaris is a virus that spreads through warm water in the lower river, most often during hot summers and amid drought-like conditions.

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 fall chinook that migrate through the lower Rogue in August, which tends to sport the hottest water temperatures. However, the virus does not harm summer steelhead, which also are present in the Rogue during the same period.

Outbreaks are most common in the Lower Rogue Canyon, where water temperatures are some of the highest measured each summer in the river.

The further upstream, the cooler the water. That's why outbreaks are considered extremely rare in the upper Rogue.

This week's conditions are a near-mirror image to those in mid-July of 1992, when triple-digit temperatures in Medford helped cook water flows that measured 77 degrees in Agness, triggering a die-off like the one Beyerlin now foresees.

A similar outbreak killed about 20 percent of the Rogue's spring chinook run in 2001. Drought-triggered outbreaks in 1992 and '94 resulted in the loss of 60 percent of the spring chinook runs, and the '92 die-off triggered a sport-fishing closure on the upper Rogue to protect the spring chinook that survived.

Managing salmon around columnaris is just part of the fabric of the Rogue. In fact, outbreaks among fall chinook once were the rule, not the exception.

Before Lost Creek Lake began operation 30 years ago, regular columnaris outbreaks kept the Rogue's production of the all-wild fall chinook run to a minimum.

But water releases from Lost Creek Lake and, to a lesser extent, those from Applegate Lake have kept the lower Rogue high and cool enough most years to stave off an outbreak. That has allowed for an explosion of fall chinook that fortifies a largely successful late-summer fishery from Gold Beach to Gold Ray Dam.

So those several hundred chinook hunkered down in Hotel Riffle represent just a sliver of what is to come.

"I fear those fish will disappear," Beyerlin says. "They'll be floating backward."

Reach reporter Mark Freeman at 776-4470, or e-mail mfreeman@mailtribune.com.