Yampa River runoff falling short

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— One doesn’t need to be a hydrologist to recognize that the Yampa River where it flows through Steamboat Springs will not match the spring runoff of 2011.

All you have to do is consult your car’s thermometer and gaze up at the rapidly receding snowline on Mount Werner to infer that the river is unlikely to go over its banks like it did last year when the Yampa peaked at 4,970 cubic feet per second on June 8.

In late May and early June last summer, the Yampa inundated parking lots and ran out of its banks on the city’s south side. Tributaries like Soda Creek poured into a city park, and the Elk River overwhelmed culverts to gnaw away at county roads.

What a hydrologist can provide is some mathematical probabilities on how close the Yampa could come to the average peak flow in 2012 before the snowpack is spent.

“It’s safe to say you’ll be below the average peaks on the Elk and the Yampa,” said Ashley Nielson, a hydrologist with the National Oceanic and Atmospheric Administration’s Colorado Basin River Forecast Center in Salt Lake City.

Nielson confirmed that a long-term forecast updated by her office late last week gives the Yampa a 90 percent chance of surpassing 1,200 cubic feet per second before it begins to drop for the season. Twelve hundred cfs is less than half of the Yampa’s historic average peak of 3,070 cfs where it flows beneath the Fifth Street Bridge in downtown Steamboat.

The forecast gives the Yampa just a 75 percent chance of peaking above 1,400 cfs, and an even 50-50 chance of topping out at 1,800 cfs. The chance of the Yampa peaking above 2,200 cfs is just 25 percent, and the probability slips to 10 percent that it will flow past the threshold of 2,600 cfs.

Nielson stressed that the current long-term peak flow forecast has a great deal of uncertainty and doesn’t rule out an unexpectedly high peak. That’s due in part to the fact that the forecast doesn’t take into account the potential for precipitation and current soil moisture in the mountains around Steamboat. Drenching rains in the next couple of weeks could change everything.

The early forecast for the Elk River, which reaches it confluence with the Yampa east of Milner, is a little healthier, with better odds of coming closer to its average peak of 3,865 cfs.

The Elk reached a historic peak of 7,000 cfs on June 8, 2011. The probability that it will crest 3,300 cfs this year is rated 10 percent, according to the a trio of hydrologists at NOAA’s forecast center.

Nielson is sensitive to the fact that the Yampa’s hydrograph — the annual chart of its rise and fall — is of great import to Steamboat’s recreation-based economy.

“We were there in late July last year and tried to rent tubes, but they told us the river was too high,” Nielson said.

Steamboat’s tubing rental companies are apt to absorb a double whammy, coming off a season when there was too much water into a season when the river could be too low for tubing earlier than usual.

Fishing guides also are dependent on healthy river flows for their income, but Jonah Drescher, of Steamboat Flyfisher, said trout fishing is good right now and the likelihood that the river flows will drop early means anglers can tempt trout with flies imitating insect hatches that weren’t available in 2011.

“It will change the timing and placement of the fishing season,” Drescher said. “Everything will be a little bit earlier. We’re already seeing bugs we don’t usually see by now.”

Mayflies known as pale morning duns and grey drakes are already in evidence on the town stretch of the Yampa, and it’s already shaping up to be a spring when stoneflies come into play.

For mid-summer, the availability of rains that cool water temperatures in the river will determine whether anglers and their guides will continue to meet with success in the Yampa.

“The river fishes great when it’s low as long as the water stays cool,” Drescher said.

If not, it will be time to head for the colder waters of the upper Elk River and high country lakes.

Nielson said her office will be able to snap a more accurate picture of when and how high the Yampa will peak later in the spring when its 10-day forecast will account more accurately for dwindling snowpack and actual weather reports.

To reach Tom Ross, call 970-871-4205 or email tross@SteamboatToday.com

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