Saving trout from drought
Among the vital statistics for the state of Colorado there is this one for fishermen: Colorado has 13,022 miles of trout streams. And more miles may be coming. An experiment under way in the Sawatch Mountains between Leadville and Aspen involves an attempt to store water (in the form of snow) and let it flow through the warm summer days in the fine, cold, aerated, fast-moving streams that trout and fishermen need.
The official name of the experiment is the Lake Creek Water Yield Improvement Project. No one seems to know of any one individual who originated it—which may bean indication of how much a touch-and-go matter the experiment is—but unquestionably it was a fisherman, or at least a streamside loafer, who thought that water stored in a murmuring brook would be better than warm water stored behind a dam. But how could that be accomplished? How could water be stored for mankind's various needs, such as irrigation, hydroelectric power, water skiing and the like, and still be permitted to flow freely as originally provided by nature? The unknown genius reasoned that if you could pile snow and have it melt slowly—rather than be washed away in a few days in a spring flood—you might be able to keep a stream bed well-watered all summer.
These vague notions came into focus during the Winter Olympics at Squaw Valley in 1960, where snow-fencing was used the way it ordinarily is in ski areas—to prevent avalanches. But there were places, such as the committee areas, where no more snow than the original fall was wanted, and there were other places where competitions were being held that needed more snow. Fences were used to guide snow to these areas.
The Forest Service made its first attempt to store water by damming snow in the summer of 1964. A fence of makeshift surplus material was erected on the Continental Divide at Independence Pass. It was securely braced against the prevailing winds of the Rockies, which come from the west. Wind velocities of 150 miles per hour are not unknown. The first storm that winter happened to come in from the east, and the fence was buried.
In October 1965 sections of a waffle-patterned galvanized-steel fence, built by the St. Joseph Lead Company, were hoisted by a Bell helicopter (660 pounds at a time) to an elevation of 12,095 feet. The officials concerned were not sure that a helicopter could lift anything at that altitude, but there seemed to be no other way to get the fencing up to the section of ridge along the Continental Divide chosen for the experiment. An A-frame fence 12 feet high, with alternate openings to let the stormy winds blow through and baffles to induce the snow to stick, was built along 1.2 miles of as desolate a height as you could hope to find anywhere. A gravel road, closed in winter, runs through Independence Pass, 12,095 feet, and the fence was built on the summit ridge at the edge of the curious flat, sheared-off area that is the top of the Pass.
There are no glaciers to speak of in the Colorado mountains. Almost all the water in the state—90%—comes from melting snowpacks. One great Colorado snowfall was registered in the winter of 1949-1950 at Wolf Creek Pass—31 feet 7 inches. Another world record of some sort was set in the town of Silver Lake, when on one occasion 8 feet 4 inches of snow was deposited on the alarmed community in three days and 13 hours of nonstop snowing. The average in the Lake Creek watershed (the official name of the 42,000-acre area where the experiment was held) is not quite 18 feet of snow each winter. The high mountains (and Colorado has 1,500 peaks above 10,000 feet) develop snowpacks that often last all summer and have on their shadowed sides gullies of ice and snow. Immense cornices of overhanging snow are built up on the ridges. These cornices fall as avalanches, and the deep and packed-in snow melts more slowly than snow lying flat on the surface and thus helps supply the water that finds its way to Cache la Poudre Creek, or Crystal River, or the Roaring Fork, or other celebrated trout streams included among the 13,022 miles.
But only part of the blowing snow is retained in those cornices. Dispersed by the high mountain winds, the snowflakes evaporate, or the storm-scattered particles eventually melt into small pools that dry up before they can flow into streams to add to the water yield. "It is dry and brittle snow at that altitude," said Kip Hinton, a Forest Service official, explaining the process, "and once the sun or wind hits it, it is gone." The hope was that snow fences would result in larger cornices so that less snow would be lost by evaporation. Evaporation is greater, of course, as more surface is exposed to the wind and sun, and as compaction of the snow behind the fence reduced the surface area evaporation would be lessened. In this sense the compacted snow would actually be dammed-up water, a real reservoir, but tilled with water in its original form—all water, even rain in the tropics, begins as snow.
When viewed occasionally during the winter from the air, there certainly appeared to be more snow behind the fences than in the adjacent, nonfenced area. A party of journalists saw the fences from snowmobiles and were impressed by jagged, ship-prow shapes of cornices that projected 30 or 40 feet over the abyss behind the woven-metal structure. At the immense height of the mountain and in the bleak solitude of the ranges stretching away to the horizons, the experiment seemed, above all, unreal. Stephen Crane in The Red Badge of Courage wrote that Chancellorsville seemed a wrong place for a battlefield, and the summit ridge of the Rocky Mountains appeared to be a wrong place for a fence. Forest Service officials were cautious in appraising the project. "We've never before undertaken a project of this magnitude," said Tony Skufca, the supervisor of the San Isabel National Forest, where the experiment is being held. "We are not attempting to justify it on an economic basis. It is being undertaken to learn about costs, techniques and hydrologic predictions." The obvious reason for the caution was that the most effective fences would have to be placed in the most remote regions. They would have to add a lot of water to the usual supply to justify their cost.
Measurements taken last January indicated that there was a 700% increase in the amount of snow recorded behind the fence, compared to the immediately adjacent area where there was no fencing. How much more water this would produce, however, remained guesswork until stream-flow measurements were taken after the snow melted. Last month the Forest Service reported: "Snow accumulation behind 1.2 miles of fencing was capable of producing 38.9 acre feet of water. On the same area, without fence, 18 acre feet." The report added that, while the Forest Service was enthusiastic about these early findings, "we are definitely in no position to say that Lake Creek watershed is the answer to the world's water problems. We're still very much in the observation stage of the project." Part of the trouble appears to be that an increase of 20.9 acre feet is not very much when you are talking about water storage to people concerned with irrigation or power projects. Lake Mead behind Hoover Dam stores 32,471,000 acre feet. The Colorado River near the Glen Canyon dam flows (on the average) 10,000 cubic feet per second. So the 20.9 acre feet stored by the fences, amounting to 910,000 cubic feet in all, is a drop in the bucket. All the water thus stored would sweep by a point in the Colorado River in a few minutes.
But wait a moment. Water stored in a running stream is different from water stored behind a dam. It is flowing. It is, in effect, stretched out in a long thin line rather than flattened into a reservoir. Those 20.9 acre feet are nothing to an irrigation project. But to a trout stream they may mean the difference between life and death. An acre foot of water contains 43,560 cubic feet. Extended in a small brook—say a little feeder stream four feet wide and two feet deep, overhung with alders and with pools and riffles—those 20.9 acre feet would reach almost 22 miles. A cubic foot of water is 7.48 gallons. As one enthusiastic angler said, "It's enough to keep a stream flowing." His conclusion was that those 20.9 acre feet, flowing at the rate of a cubic foot a second, or 450 gallons a minute, would keep that hypothetical feeder stream alive for 10 days. Thus 20.9 acre feet is not enough to raise a crop on irrigated land, but it is enough to surround a lot of rainbow trout. That is the significant fact. The Forest Service plans now call for a total of 13 miles of fence to enclose a lot more snow in coming winters.
PHOTO
A SECTION OF THE BIG FENCE THAT WILL TRAP THE WINTER SNOWS FOR SUMMER USE