Just as the Colorado River starts getting too big for commercial rafters’ comfort levels, the Roaring Fork is hitting its stride, local outfitters report.

The Colorado at Shoshone in Glenwood Canyon was running at close to 4,700 cubic feet per second this morning ” commercial rafting companies generally call it quits for that section of the river when it goes above 5,000 cfs, since it can be a long, cold swim for anybody tossed from a boat.

“When it gets that high, the Fork gets really good,” said Blue Sky Adventures owner Gary Hansen.

“Shoshone is cranking right now,” confirmed Chris Vogt, co-owner of Glenwood Canyon Kayak in Glenwood Springs, as the flow meter read 4,690 cfs at the popular rapid. “This is a great time to take a raft trip down Shoshone. The waves are big and the splashes are huge.”

But just as the Shoshone run started bumping into that 5,000 ceiling, the upper Roaring Fork at Slaughterhouse Falls crept above 600 cfs ” a welcome sign for commercial raft guides who anticipate putting their first guests in the water for the Class 4 run this week.

“It needs to be at least 600 [cfs], which it just got to,” said Bob Harris, owner of Blazing Adventures. He considers anything between 600 and 1,200 cfs prime for commercial trips down the Slaughterhouse section.

Aspen Whitewater Rafting guides checked out Slaughterhouse today in preparation for the company’s first commercial trips of the season through the section of the Fork just below Aspen, according owner Jim Ingram.

Both Aspen Whitewater Rafting and Blazing Adventures are offering $39 locals’ specials to run either the Slaughterhouse section from Stein Park to Jaffee Park at Woody Creek, or the gentler Woody Creek-to-Basalt section.

“Slaughterhouse is not for everybody ” it’s a Class 4-plus section,” Harris said. Generally, rafters have to be at least 16 years old and have some paddling expertise. “It’s pretty much nonstop whitewater ” Class 3-plus with a series of 4-plus and 4s.”

From Woody Creek to Basalt, the Fork is a Class 3 run with some Class 4 water, he said.

Whitewater is rated in Classes 1-6, with Class 6 considered unrunable.

Kayakers are hitting Slaughterhouse and Shoshone, and just this week, flows in the Crystal River inched upward to desireable levels.

The Crystal, including the Meatgrinder section below Redstone, was running at 1,080 cfs early today.

“We’re just beginning to get into the good flows for that run,” Vogt said.

For nonexperts, Vogt recommended the Cemetery Run on the lower Fork near Glenwood, which was running at 3,000 cfs-plus this morning ” good for an intermediate-level paddler. Shoshone, he advised, is now best left to advanced kayakers.

While this week’s warmer temperatures should bring a surge of snowmelt out of the high country, Harris and Ingram are both predicting peak flows next month.

The Arkansas, meanwhile, appears to be benefitting from diversions from this side of the Continental Divide, Harris noted.

The Pine Creek section of the Arkansas jumped from about 400 cfs on Monday morning to 900 cfs early today.

“They’re not only getting their runoff, they’re getting some of our runoff,” he surmised.

The Arkansas lures local rafting expeditions when Independence Pass, east of Aspen, opens to traffic Thursday, May 25.