A `10-karat day' for Diamond Lake.

Byline: Susan Palmer The Register-Guard

DIAMOND LAKE - Ninety million fish are dead.

You'll have to forgive Dave Loomis for being ecstatic about it, but he has been working toward this day for a decade.

The Umpqua Watershed district manager with the state Department of Fish & Wildlife, Loomis has just overseen a $5.5 million effort to eradicate a voracious minnow responsible for ruining Diamond Lake, a once pristine body of water high in the Cascades.

On Friday, a day after 11 boats and 50 workers spread thousands of pounds of poison across the lake, thousands of silvery fish carcasses lined the shore. Still more floated belly up across the surface of the water. Some were tiny, less than an inch long. Others ranged up to 6 inches long.

Watching from inside the Diamond Lake Resort while the first storm of the season scattered snow on nearby slopes, Loomis put it this way: "Yes, Diamond Lake, there really is a Santa Claus," he said. "There will be a white Christmas and happy New Year in 2007."

Not for the minnows, but for Oregon anglers who remember Diamond Lake the way it used to be, when catching a 2-pound or even a 5-pound rainbow trout was the norm, and the water was a sparkling blue instead of the green-choked algae of recent years.

State officials hope that poisoning the tui chub, a minnow indigenous to the Klamath Basin, will bring those days back again.

Formed after a volcanic eruption several thousand years ago, Diamond Lake wasn't home to any fish until 1910, when the state first stocked it with rainbow trout.

While the shallow lake doesn't provide suitable habitat for trout to spawn, it is a bug-filled cornucopia, and the trout planted there grew big fast. Just 20 miles north of Crater Lake, Diamond Lake became a popular destination for anglers and people who simply love the outdoors.

It's idyllic, nestled between Mount Thielsen to the east and Mount Bailey to the west, the slopes rising from its shores covered in Douglas and true fir, ponderosa and lodgepole pine.

But the conditions that made it a wonderful trout fishery also made it hog heaven for the tui chub, originally released into it as live bait. The chub outcompeted the trout for the insects. Their waste fed the naturally occurring algae, and they also ate zooplankton, microscopic animals that graze on algae. They first decimated the habitat in the 1940s.

State officials poisoned them then, and they didn't come back until the early 1990s, leading Fish & Wildlife officials to close the lake several times. It has taken 10 years of public hearings and environmental impact statements to get permission to poison the fish again.

It's not as alarming as it sounds. Rotenone, the pesticide approved for the job, comes from tropical plants. It breaks down in days or weeks - depending on the weather - into carbon, hydrogen and oxygen. It interferes with the breathing ability of fish, killing them quickly, but it is not dangerous to birds or mammals.

This week's treatment of the lake took the world's whole annual stockpile of rotenone, Loomis said, consisting of 540 drums containing 107,000 pounds of powdered rotenone plus 9,300 gallons of the liquid version, packed in 30-gallon drums.

On the lake Friday, as snow gave way to rain and then intermittent shafts of sunlight, seagulls feasted on the bounty of dead fish. An osprey soared overhead. Waterfowl dabbled near the dock.

Loomis pronounced the lake safe for people and animals.

"And it's 100 percent fishless. There's no doubt in anybody's mind," he said.

Next spring, fisheries workers will stock the lake with about 75,000 fingerling and 75,000 catchable trout.

That's good news for Rick Rockholt, marketing manager at the Diamond Lake Resort. The lake used to attract 100,000 angler visits a year, but the number has dropped recently to 5,000. And fishing brings other forms of recreation to the area, he said.

"When the lake is not healthy, people don't come," Rockholt said.

When visitors do return, they'll find boat-washing facilities at the north and south ends of the lake to help keep fish eggs and fish from ballast tanks out of the lake, Loomis said. They'll also find an intensive education campaign to help people understand that Diamond Lake is still vulnerable.

Not everyone is happy with the solution. Environmentalists worry that partial drainage of the lake to concentrate the fish before poisoning may damage sensitive wetland plants. And they worry that the chub will come back again, leading to yet another round of pesticide use. They wonder why predator programs that have worked in other lakes, such as introducing brown trout, salmon or tiger muskie - a sterile cross between muskie and northern pike - to feed on smaller fish, haven't been tried. But Loomis said that solution wouldn't work here.

"It would take years, and there would be no guarantee you'd get the fishery back," he said, because there were just too many tui chub in Diamond Lake.

Loomis said he cares about the health of the Diamond Lake ecosystem. His grandfather grazed sheep on nearby hills and fished the lake. His father and uncles fished it when they were growing up. And Loomis has pulled his share of trout from it, too. He feels good about the plan and the outcome, he said.

"It's a priceless, precious 10-karat day for Diamond Lake," he said.