Printed on: May 16, 2013

In the Woods

F&G's plan comes together in war against rainbows

Rob Thornberry
Post Register

After years of hoping and waiting fruitlessly, Dan Garren is finally getting his wish.

This weekend, the Bureau of Reclamation is releasing a controlled flood from Palisades Reservoir. The peak is expected to reach 18,000 cubic feet per second at the Irwin gauge on the South Fork of the Snake River. The goal for the Heise gauge is 20,000 cfs.

"We are pretty excited that this is happening," said Garren, the Idaho Department of Fish and Game's fisheries manager in the Upper Snake Region. "It is difficult to get all the factors in the right place at the right time to make this work, but this year everything has lined up."

Garren's hope is the flows will mimic pre-dam conditions on the famed river and promote Yellowstone cutthroat spawning while dampening rainbow spawning.

Garren and his partners have worked on modeling the flows for nearly a decade, and this year is the first time it will come together, with lots of water and at the right time.

Because the bureau's major goals for Palisades Dam are flood control, irrigation and power generation, the ability to make a controlled flood to benefit fish is very limited. Some years, the snowpack dictates a big release all spring. Other years, drought conditions dictate minimal releases.

This year, the combination of low snowpack and plentiful room to catch the flood at American Falls Reservoir have allowed reclamation officials to help Fish and Game.

"Everything came together and we had enough lead time to make it happen," said Mike Beus, a hydrologist with the Bureau of Reclamation. "The most important thing is American Falls has the space to recover the water."

The managed flood is part of a three-pronged attack on rainbows, a chance for the department to help native cutthroat gain an upper hand.

This week, the bureau is gradually increasing water from Palisades Reservoir as part of a multi-agency effort to help Yellowstone cutthroat trout.

The flows were at 13,100 cfs Wednesday at the Irwin gauge and are expected to reach 18,000 cfs Saturday and Sunday. Flows will return to their historic average of 13,000 cfs for Memorial Day weekend, according to a bureau news release.

By mimicking pre-dam flood flows this weekend, Garren believes cutthroat will actively spawn as water levels drop.

At the same time, he hopes rainbows, which spawn earlier in the month, will struggle during the flush. In theory, he said rainbow eggs and emerging fry will be damaged by higher water.

"We are very optimistic about this," Garren said. "If we could do this three or four years in a row, we would really have a good understanding of the effectiveness of it and its ability to stem the tide of rainbow trout in the river."

For more than a decade, Fish and Game biologists have tried to limit rainbow populations on the famed cutthroat stream because of fears that rainbows will eventually take over the river.

If cutthroat trout are crowded out of the South Fork, one of their remaining strongholds in the West, the federal government could list the species as threatened or endangered. Federal listing could affect everything from irrigation to recreation.

Garren said biologists will know how the managed flood worked in the fall of 2014 when biologists survey the river.

"When we sample the river, we should see lots of young cutthroat and very few young rainbows if this works," he said.

Biologists have also encouraged harvest of rainbows with a bounty program.

Thousands of rainbows have been implanted with tags that can be redeemed for bounties that range from $50 to $1,000.

The bounty program has been slow to take hold, but last year, Fish and Game conducted a creel survey on the river and found that anglers are killing lots of rainbows.

"Anglers seem to be stepping up their game and harvesting rainbows," Garren said. "We believe five times as many rainbows are being harvested than were six or seven years ago before the incentive program was put in place."

Fish and Game has also built -- and perfected -- fish traps on Burns, Pine, Rainey and Palisades creeks. All the fish are trapped and sorted. Cutthroat are released back into the critical spawning tributaries while rainbows are culled from the streams and trucked to nearby fishing ponds.

"We just rebuilt those traps and we are much, much more effective with those traps than we were in the early 2000s when we first started this program," Garren said.

Biologists also are using electro-fishing gear to cull any resident rainbows living in the spawning tributaries above the weirs.

"We are being very aggressive," Garren said.

Garren said BOR deserves credit for managing flows to help cutthroat, pointing out that none of the water released during the flood will be lost to irrigators. It will be stored in American Falls Reservoir and used by downriver irrigators.

"It is always great when you have partnerships that are working to the benefit of all the concerned parties," he said.

Now, Garren waits. He's spent a decade building a program to help cutthroat trout, and -- by extension -- anglers and irrigators.

"We are just keeping our fingers crossed," he said.

Because the South Fork will be out of shape this weekend, it is time for anglers to look elsewhere for thrills.

Fortunately, this time of year, there are plenty of options.

The first is the Henry's Fork, which has had good caddis hatches over the past week. Anglers are also catching fish with streamers and nymphs.

Another choice is Chesterfield Reservoir, which was apparently red-hot last weekend. Anglers reported catching fish from the banks, while trolling and on float tubes.

Although it is probably tailing off, anglers are also doing well from the banks at Palisades Reservoir. Fish congregate near the shorelines when the ice melts, and fishing can be quite good.

The ice is off Henry's Lake.

The lake opens to fishing May 25, and ice-off is eagerly watched by anglers who want a chance at one of the lake's huge trout.

The early loss of ice is a benefit to boaters because fish will leave the shorelines in the coming days and spread throughout the famed lake.

While boaters will benefit, shore anglers will likely find tougher conditions on opening weekend. Fishing from the shore is best when the ice leaves just before the Memorial Day weekend opener.

As always, anglers are now going to turn their attention to the weather forecasts and pray for mild weather.

Fish and Game has been setting gill nets as part of the department's annual population survey. The results of the gill net surveys will be available next week.

Ducks Unlimited is hosting an open house to introduce the public to its latest eastern Idaho purchase.

Last fall, DU acquired the former Western Wings property near Roberts, in the Market Lake area.

The open house is at 3:30 p.m. June 7.

The organization's conservation staff will be present to field questions about the plans for the area.

For information, call (208) 467-9152.