Despite bitter cold and a driving snowstorm that whited out the sky, rainbow trout fishing was so hot Friday at Diamond Lake that even Josh Uptegrove can catch fish.

Despite bitter cold and a driving snowstorm that whited out the sky, rainbow trout fishing was so hot Friday at Diamond Lake that even Josh Uptegrove can catch fish.

The 25-year-old Eugene man contributed five rainbows to the fish basket slung over the side of a boat that Uptegrove and two friends used to mine Diamond Lake for three limits of trout Friday morning.

"I admit, I'm not the best fisherman, I know," Uptegrove says. "This is the only place in Oregon that I've actually caught a fish, so, yeah, that's how good it is."

To Diamond Lake anglers, the 2010 fishing season will be known as the Year 4 A.R. — year four after a rotenone treatment killed off millions of invasive tui chubs to reclaim one of Oregon's most insect-rich lakes for stocked rainbows.

And the fourth chub-free fishing season has started off with a flurry far bigger than the sideways snowflakes that blew Friday over the Diamond faithful and made the normal surface reflection of Mount Bailey more like a rumor.

With the lake stocked with an estimated 200,000 rainbows and nothing under 11 inches in sight, Diamond anglers are braving the May storms to generate the kind of fishing successes more often enjoyed in an old man's reminiscing than reality.

It's not been uncommon to see anglers here hooking a trout every 10 minutes while using just simple set-ups such as a worm dangling six feet under a bobber or floating a ball of chartreuse PowerBait off the bottom, ala Uptegrove.

"I was up there Thursday, and it was snowing all day," says Holly Truemper, the Oregon Department of Fish and Wildlife's assistant Umpqua District fish biologist monitoring trout catches here. "And I couldn't believe it, but people were bringing in lots of fish all day.

"A lot of people are releasing 10 to 15 fish, plus keeping a limit," Truemper says. "I'd say that's pretty good."

And if that's not enough, one of those 200,000 rainbows is sporting some spaghetti bling that can be worth a couple monthly boat payments to the lucky angler who catches it.

Under a permit that authorized Kokanee Power of Oregon's fundraising derby here last September, Truemper tagged and released a rainbow that, if caught during the derby, would have netted its captor $500.

That fish remains somewhere in the lake, with Kokanee Power teaming with the Diamond Lake Resort to honor that $500 prize should it get caught this year.

The long, thin, plastic tag resembles a piece of spaghetti and has numbers on it. The trout likely is about 19 inches long and 3 pounds now and if caught, the tag will be given to Truemper for verification before payment, says Rick Rockholt, the resort's marketing and events coordinator.

"It's a marketing ploy, but it's fun, and we'd love to see someone win $500," Rockholt says.

John Fisher already has spent two May days trying to be that someone.

"Getting paid to catch a fish," says Fisher, of Medford. "Now that's all right."

The days have been better than all right at this eastern Douglas County lake since 2006's successful $5.6 million effort to kill off an estimated 100 million tui chub, a non-native species likely introduced as a bait fish.

The chub's presence altered the lake's ecosystem so badly that the water was at times unhealthy and stocked trout could barely survive.

After the rotenone treatment, the lake was restocked in 2007. Since then, the rainbows have accrued quick growth rates because of the vibrant natural insect population that numbers 300 pounds of bugs per acre of lake bottom.

The result is the lake has been nothing but the top-drawer trout fishery that has dominated Oregon's rainbow fisheries much of the past century.

Hard to believe this fourth post-rotenone fishing season could get better. But early indications are it might.

Even though the season started with the lake all but covered in ice, the angler catch rate so far this season has averaged 3.5 trout per angler — a hair under the 5-fish daily limit but twice that of last year's catch, Truemper says.

The largest trout measured by creel checkers so far this season was 25 inches long, Truemper says. The longest trout measured here all of last year was 26 inches.

The majority of the trout now finning in the lake are fish stocked last year as fingerlings.

Those fingerlings now measure 11 to 13 inches — well above the 8-inch minimum to be kept.

"The way these fish grow, you won't find a trout under 12 inches here by the end of June," Rockholt says.

The fingerlings stocked in 2008 are now 16 to 19 inches long.

Other than the $500 trout, those 19-inchers are prized by trout-eaters because the bag limit allows just one trout over 20 inches a day. So a stringer of four 19-inchers and one over that 20-inch line represents the most rainbow biomass any angler can legally pull out of an Oregon lake.

"That's enough reason to spend the gas money right there," says Fischer, a gas-station attendant.

Truemper says anglers so far have been catching four of the smaller rainbows for every one trout over 15 inches. Most of the bigger fish are the Eagle Lake strain of rainbows stocked because they will prey on smaller, non-native fish should any invaders try to overtake the lake again.

Heading into Memorial Day weekend, Diamond Lake fishing couldn't be any simpler.

Don't bring the fancy chironomid nymphs and woolly bugger flies that work so well through summer and fall. That's because those 300 pounds of insects per acre remain hunkered in the mud.

"The water's not warm enough to start any hatches yet," Rockholt says.

Most anglers aren't bothering to troll, either, since simple is better here in May and early June.

Worms and bobbers or the standard PowerBait rigging — an egg sinker, 5-pound leader with a small treble hook at the end covered by a balled-up piece of the doughy bait — are all that's needed.

After all, it worked for Uptegrove.

Hit limit of fish already caught and his rod stowed, Uptegrove sat bundled in a thick coat looking more like Kenny from South Park than a successful angler.

As buddy Jeremy Malloy reeled in his fifth fish, Uptegrove eschewed the sideways snow to reflect on what it's like finally to call this pasttime "catching" and not just "fishing."

"This is pretty cool when you see fish and actually catch fish yourself," Uptegrove says.

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