A stretch of the Rogue River upstream of Dodge Bridge is known to old-timers as McGraw's after the former owner, while relative newcomers call it Duffy's after its current owner.

But upper Rogue driftboaters last week knew the reach as Impassable after this winter's high water moved the gravel around enough and plopped a few 100-year-old oak trees into it to create a new navigational hazard.

It's just one part of the upper Rogue altered by high water this winter, and it has marine-patrol officers playing a cat-and-mouse game with nature as they try to figure out if, when and how to alter some of these features for driftboating safety — or whether they should wait to see if future high-water events this winter wash those ills away.

"Usually at this time of year, guys in driftboats know what they're doing," says Jason Denton, a marine deputy for the Jackson County Sheriff's Department. "But those guys who go down on memory really need to pay attention.

"Some of that stuff out there can kill somebody, and right now I don't know how much of it we can clean up," he says.

Denton's navigational nightmares normally come in spring when the orange armada of inflatable kayaks invade the upper Rogue, where root-wads, overhanging limbs and odd hydrology regularly conspire to separate floaters from their crafts.

But this winter's stormy events have upped the ante during the normally staid winter steelhead fishing season, when most driftboaters who ply the upper Rogue reaches are seasoned boaters who can normally navigate the stretch as if they were walking to the bathroom in the dark.

Many of the alterations occurred earlier in the season during two high-water events that pushed the upper Rogue within inches of flood level at Dodge Bridge, according to U.S. Geological Survey records. But they didn't come into play for boaters because upper Rogue flows remained relatively high until last week, when dry weather and a drop in Lost Creek Lake releases caused new hazards to pop up throughout the popular boating stretch.

Places like the first rapid downstream of the Shady Cove boat ramp, water downstream of Fishers Ferry boat ramp near the old Gold Ray Dam site and the stretch downstream of the Slide Hole upstream of Trail have all been flagged as spots with dicey passage.

The worst changes have occurred within a stretch of water between the Taklema and Dodge Bridge boat ramps, where a combination of a snaking channel, loose gravel, an aggressive drop in elevation and massive oaks with spiny root wads all conspire against boaters. 

"It changes dramatically every year," Denton says.

This year's change begins at a place known as Buzzard Hole, where the Rogue tapers over a wide gravel bar before plunging into a deep hole lined by large boulders placed to fortify the bank against the water's force. It's name comes from turkey vultures that roost in nearby trees waiting to feast on dead spring chinook salmon that collect in an eddy there.

But the buzzards might be a different omen if conditions don't change.

High water deposited two large oaks on the shallow approach, blocking the traditional pathway. At last week's flows, driftboats traveled to the right of the trees, but in shallow water that likely won't be possible during summer flows.

Denton intends to wade out and trim the root-wads to render them less dangerous to boaters.

Trimming of woody material in the Rogue is done after consultation with Oregon Department of Fish and Wildlife biologists to ensure wild fish habitat is not unnecessarily damaged, Denton says.

While a bane to boaters, overhanging branches and partially submerged logs provide refuge for young wild salmon and steelhead rearing in the river, as well as resting spots for migrating adults.

"If it's not going to hurt anybody, we leave it for the fish," he says.

The most glaring obstacles, however, have been farther downstream at Duffy's, where the river parts into three channels around two gravel islands. Since the New Year's Day flood of 1997, either the left or center channels have been the driftboaters' thruway.

Last year, high water deposited a large root-wad in the only passable channel — the center — and it had to be winched out by a private contractor. That type of emergency work is paid through a $20,000 Oregon State Marine Board fund set aside to handle navigational emergencies, says Randy Henry, who oversees the Marine Board's law-enforcement program.

Denton powered the marine patrol's jet boat into that same reach last week to inspect the channels, all of which became impassable as water levels dropped below 2,300 cubic feet per second. He chainsawed a log jam to allow the far left channel to be passable again.

"That's going to be the best way to go, for now," Denton says.

Denton hopes a future storm will alter that area's gravel enough to force more water down that left channel, or those who know it as McGraw's and others who know it as Duffy's will see that Impassable moniker linger.

"If nothing changes and the river drops six inches, you won't get over that gravel bar anywhere," Denton says. "It'll be interesting to see."

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