January 31, 2008 – Bend Bulletin Low Flows and Ice Can Affect Fish Populations in the Deschutes

The Deschutes River upstream of Farewell Bend Park was iced over in spots last week. The river can be good to fish in winter, but variable conditions can be tough to predict.

Why the low flow?
The region’s water managers hold back water behind Crane Prairie Dam and Wickiup Dam in the winter to ensure that irrigators will have enough water in the summer.
The flows below Wickiup Reservoir have dropped as low as 25 cubic feet per second this winter, which fish biologists say is a detriment to the redband and brown trout populations.
Low flows become less pronounced as anglers move downstream, although the effects are still noticeable.
For all the drama of the Deschutes River in the winter — the fluctuating flows, the bitter cold, and the occasional icing over (as happened just last week) — there are still those anglers who cannot get enough.

I grabbed my fly rod and trudged through the snow, hiking along the river upstream of Bend.

The trail, typically crowded with joggers, hikers and bikers during warmer months, was all mine — as was the river.

The only sounds were the crackling of the ice on the stream, and the rush of water in those unfrozen areas where the river ran freely.

I found one of those spots and tied on a blue wing olive, a go-to fly in the winter.

It was not exactly a productive day for fishing, but the solitude and scenery were hard to beat on a bright, crisp day, the snow and ice glistening in the sunshine.

“It’s not necessarily the most productive time of year, as far as numbers (of fish),” says Dave Merrick, shop manager at Fly and Field Outfitters in Bend. “It is the time of year when you have sections of the river all to yourself. For some of us, that’s a great thing. But it’s not for everybody.

“If you’re willing to brave the cold, there’s some pretty darn good fishing out there. It’s one of my favorite times of year to fish.”

But low water flows during the winter can hamper the redband and brown trout populations on the Deschutes, according to Ted Wise, a Bend-based fisheries biologist for the Oregon Department of Fish and Wildlife.

The region’s water managers hold back water behind Wickiup Dam in the winter to ensure that irrigators will have enough water in the summer.

Wise says the Deschutes flows, which have run as low as 25 cubic feet per second (cfs) this winter, compromise available spawning habitat for redband and brown trout and leave smaller fish more vulnerable to larger fish in the reduced habitat.

When the Deschutes freezes, as parts of the river did last week, lower water flows increase the chances of the water column completely freezing in sections, killing all the fish in those areas. Wise says he is not aware of that happening so far this winter.

“It would take a much more intense freeze,” he says. “But it may have happened (last week) in some side channels. Sometimes fish can swim away to another habitat.”

The dramatic fluctuation between raging summer flows — as high as 2,000 cfs, according to Wise — and low winter flows also causes problems for fish, the biologist notes. During periods of low winter flows, the bare bank is exposed to the freeze-thaw cycle, which loosens the soil, Wise explains. When the flows rise in the spring, the result can be a massive loss of soil and loss of riparian plant cover for trout.

“What our inventories have shown us is in the years when we see low winter flows, our (fish) populations in the upper river decrease,” Wise says. “When we see a series of higher winter flows, we see an increase in our fish populations.”

Wise and other ODFW officials are working with a host of other agencies to find some common ground on the issue of flows on the Deschutes. The Water Resources Department, the Deschutes River Conservancy, the Upper Deschutes Watershed Council, the Central Oregon Irrigation District, the North Unit Irrigation District, the Lone Pine Irrigation District and the Bureau of Reclamation are all involved in the discussion.

“What can we do to fit the needs of the Upper and Middle Deschutes for wildlife and river ecology, and still meet the needs of the growth we’re seeing in Deschutes County?” Wise asks. “We need to find a balance that works for the fish and all the other needs that we have.”

While all that is being resolved, anglers are still enjoying the Deschutes in the winter. Merrick says that fish can adapt to the low winter flows and sometimes become opportunistic. Midges and mayflies tend to work best for fly-fishing, he says.

Merrick notes that anglers should check flows before venturing out to the river. They can be low or high, but the key is finding a time when flows have stayed consistent for a few days.

“Little channels that were dry before can hold fish just a week later,” Merrick says. “Low water can make the fish more concentrated. When you find them you can catch a lot of them, but (low water) leaves them pretty vulnerable.”

Low flows have caused problems mostly for fish populations on the upper portions of the Deschutes, according to Wise. Trout in the Lower Deschutes, from Lake Billy Chinook downstream to the mouth, are not as affected.

“The area where you see the more profound effects are those areas immediately below Wickiup Reservoir,” Wise says. “As you move downstream, the overall effects are a little less pronounced. But you still see bank disparity.”

The Lower Deschutes near Maupin, famous for its steelhead runs in the fall, can still be a good place to fish for redband in the winter, according to Merrick.

“The water temperatures (near Maupin) are a whole lot better than they are in July or August (when they’re too hot),” Merrick says. “Actually, it can be some of the better water temperatures and conditions of the year.

“Of course, flows change things.”

Mark Morical can be reached at 383-0318 or at mmorical@bendbulletin.com.