High on a snow-deep mountain in eastern Arizona, a crew of biologists is working to protect a million fish in an ice-locked lake. The men are battling "winterkill"—an old enemy of almost every high-country trout lake. There's every reason to believe they'll conquer it. They did last winter, with a new weapon that has made possible a jackpot of trout and can mean better fishing in many other states.
The name of this fish-loaded water is Big Lake, located on a lofty shoulder of Mt. Baldy, 30 miles southwest of Springerville, Ariz, and near the timber line of the Apache National Forest. It's held by a low dam at the neck of a shallow snow basin. The name is a contradiction—Big Lake covers only 575 acres and averages just eight feet deep. But in 1954 it produced a record 225 pounds of fish per acre of water. Few so-called "good" trout lakes anywhere can produce 50 pounds.
Big Lake is fertile, so full of natural foods that trout grow 1� inches a month. Thus instead of expensive creel-size fish which are put in many U.S. lakes, Big Lake is stocked with inch-long fry. Raised in a hatchery, the lake's trout caught in 1954 would have cost $100,000. But stocked as fry, the bill was only $1,250.
This sounds like an easy way to get sensational, low-cost fishing. But it took 25 years, research by five biologists, the work of 150 men, and a unique invention before Big Lake's record trout production was finally won. To do it, deadly winterkill had to be defeated for the first time. Like high-altitude lakes in many other states, Big Lake is buried in snow and ice during the winter months. The water may freeze five feet deep, and be covered by heavy drifts. Trout are trapped below the ice, and must try to live on a dwindling oxygen supply. If the lake isn't opened, all fish will die. How many fish have been lost to winterkill in the U.S. is anybody's guess. But in Big Lake, 10 million trout were wiped out as the kill came nearly every winter, beginning in 1928, the year the first fish were planted. There was no dam across the snow basin then, it was just a shallow, spring-fed pond. There were no roads. A. W. Yoder, assistant director of the Arizona Game and Fish Department, remembers packing the trout to the water on horseback. The following spring, when he returned, the fish were all dead. It was the start of a lethal cycle that continued until 1953, broken only by a few summers of fishing, when the previous winters had been mild.
SNOW IS THE VILLAIN
Biologists studied the lake and concluded that in addition to the ice threat, weedbeds hastened death. The underwater weeds were beneficial when winter ice stayed clear. Sunlight kept them releasing oxygen in the water. But under snow-covered, opaque ice, the weeds ceased throwing off life-giving oxygen and produced poisonous nitrogen.
Heading "operation thaw" at Big Lake this winter is the young scientist who solved both problems. Biologist Jack Hemphill, now Chief of Fisheries for Arizona, finally reached the ice-locked lake in 1950 by riding a tractor-like Weasel part of the way, then snow-shoeing five more miles. For three winters he tried blasting, cutting and drilling the heavy ice. All failed, and more trout died. Then he hit on the simple but revolutionary idea that saved 350,000 fish in 1953: why not try compressed air to circulate warmer lake-bottom water up to the ice?
The coldest water in a frozen-over lake is just below the ice and near 32� F. From there on down, the water is warmer, with 7 to 8� higher temperature on the bottom. When circulated this water will melt ice.
Hemphill convinced department director John M. Hall that the idea was worth a try. During the summer of 1953 the fisheries crew had an unusual job: drilling thousands of quarter-inch holes in 2,700 feet of plastic hose. That fall, the perforated hose was anchored across a wide bay and an air compressor on shore was connected.
Ice came in November, and deepened each day. The oxygen content of Big Lake dropped from a healthful 9.1 parts per million to a deadly 2.1. It was time to start pumping. In biting cold, 25� below zero, the crew took turns cranking the compressor. It finally fired, caught, and air began pushing through the sunken hose. Five hours passed. Finally, in late afternoon, a hole suddenly opened in the ice and slowly widened. Big Lake was breathing again. In two weeks, it was spanned by a channel 300 yards wide.