May 06, 2003

Water, water everywhere, but drought effects linger

By Charlie Meyers, Denver Post

In the topsy-turvy world of Colorado water, the more it rains, the less it pours; dry sometimes becomes wet; what goes up might not come down and not even the keenest experts can predict what might happen next.

Consider these scenarios:

If you're a fisherman who treasures the Cheesman Canyon area of the South Platte River, you might be placed in the odd - and, perhaps, indefensible - position of hoping it stops raining in the Denver area.

The reason? A recent plenitude of precipitation, coupled with holdover moisture from the March blizzard, has prompted Denver Water, the primary provider for the region, to severely cut back flows from Cheesman Reservoir in a desperate effort to store more water against the uncertainty of the months ahead.

A bare minimum of 25 cubic feet per second - enough to keep the canyon's trout damp, but not much for fishing - currently is pouring from Cheesman Dam.

Dave Bennett, water resource engineer with Denver Water, explained that low water use in the city, coupled with rain and low-elevation runoff, has enabled his agency to keep pace with its customers' needs without a major assist from Cheesman Reservoir. This provides a rare opportunity to gather vital water in a reservoir where storage is critical not only for future water needs, but also to dilute potential ash flows from the Hayman fire that burned the surrounding slopes.

"This was the best time to cut back the Cheesman release because we're getting good flows into the river from smaller creeks just downstream and because cool spring temperature prevents stressing the trout," Bennett reasoned.

The Cheesman flow should accelerate in a week or two - unless substantial rainfall returns to the metro area.

A crazy quilt of water exchanges creates situations that may seem bizarre to fishermen who don't keep a scorecard. In the strange case of the upper Colorado River basin, we have situation in which an ample snowpack already has begun to leak lots of runoff.

Most of this is being captured in sorely depleted reservoirs such as Williams Fork and Granby, with not much going downstream. In the case of Williams Fork, an inflow of about 200 cfs has been pinched to just 15 cfs from the dam, a troublesome condition for that popular public fishing segment on the Williams Fork River down to the confluence with the Colorado River.

The balance will swing dramatically when the weather turns hot and dry later in the summer. That's when Xcel Energy, which operates Shoshone Power Plant downstream on the Colorado River, will issue a call on its water rights to spin the turbines that generate electricity for the region's air conditioners.

The rivers suddenly will gush water and fish and fishermen will prosper - at least for a little while.

Then there's a new, and potentially even more disturbing sequence involving a Denver Water plan for water stored in Chatfield Reservoir, an impoundment on the South Platte where the river exits the foothills in the southwest metro area.

The water agency already has installed a pumping system that can lift the upper 5 vertical feet of the reservoir's water up to its treatment plant, from which it will be spread out upon the city's lawns.

At some point next year, a similar pump will be installed at the base of the dam, giving Denver Water access to virtually the entire contents of a reservoir that has emerged as the area's best warm-water fishery. Chatfield's premier bass and walleye angling might quickly become a memory.

Bennett said all these eventualities result from a drought whose impact remains firmly intact despite recent precipitation. Celebration over a normal runoff for most of the Front Range is muted by the fact that the snowpack in that part of the South Platte drainage that supplies much of Denver's storage ranks far below average.

Bennett said that while his agency hopes to fill Cheesman Reservoir, there's little hope for Antero Reservoir, drained last summer at the apex of the drought.

Elevenmile Reservoir, presently half-full, should swell to approximately three-fourths capacity and the river below the dam is expected to maintain a stable, yet relatively low, flow that probably won't exceed 100 cfs.

"A lot depends upon what happens with the ash and debris from the Hayman burn area and whether we need more water for dilution in Cheesman Reservoir," Bennett tried to explain about a situation that, in truth, may be imperceptible.

If there's anything fishermen can expect about Colorado's water situation, it's that things are bound to change.