Thomas L. Rogers's rowboat sighting and the "Slimy Slim" wave, Payette Lake

Payette Lake sits at McCall, in the mountains of central Idaho. It is a glacial lake, about 6 miles long and 2.25 miles wide. Near the northwest shore it drops to 392 feet. Stories about the water were old by 1944. A Native American belief in an evil spirit in the lake is often repeated, though it is unclear who first recorded it.

In 1920, by most accounts, a crew of railroad tie-cutters near the upper end of the lake saw what they took for a log. "The log began to move forward. Then the log began to undulate. Then the 'log' created its own wake as it rapidly left the area."

July 2, 1944. That is the date TIME later gave for the start of the sightings. Within weeks, about 30 people had seen the animal, among them, in TIME's words, "Republicans and teetotalers." They found themselves staring at a "periscope-like head."

In August several groups, one of them near the Narrows, a rocky passage between the north and south parts of the lake near Ponderosa Park, described it as 30 to 35 feet long. They described a dinosaur-like head with pronounced jaws, humps like a camel and shell-like skin. A later Idaho Fish and Game account says people saw it writhing off shore, displaying a series of three humps.

The best-known statement came from Thomas L. Rogers. TIME called him an "auditor of a stodgy Boise firm." He talked for publication after the serpent sloshed past his rowboat.

"The serpent was about 50 feet away and going five miles an hour with a sort of undulating motion. His head, which resembles that of a snub-nosed crocodile, was 18 inches above the water. I'd say he was 35 feet long." Rogers said nothing of colour or sound. The exact date and place of his sighting have not been traced.

TIME ran the story on 21 August 1944 under the animal's new nickname, "Slimy Slim." Photographers stalked the lake. Fishermen openly trolled it with deep-sea tackle. The Idaho Sunday Statesman answered with a tall tale of Paul Bunyan, Babe the blue ox and a sturgeon left with a three-humped spine. No photograph from that summer has ever turned up, and no official investigation followed.

The sightings did not stop. In September 1946 about 20 witnesses, among them Dr. G.A. Taylor of Nampa, saw something that "appeared to be between 30 and 40 feet long and seemed to keep diving into the water." In 1947 the fisherman F.M. Christiansen admitted, "I sure changed my mind."

The first explanation, as the 1920 crew showed, was a floating log. Later writers suggested a sturgeon that had come up from the Snake River before the dams were built, or a seiche, a standing wave raised by sudden changes in air pressure. Gary S. Mangiacopra reportedly raised the possibility of seals cut off by dams. None of these has been tied to the account Rogers gave.

In 1954 A. Boone McCallum, editor of the Star-News, ran a contest to rename the animal. Governor Len Jordan and state legislators judged it. The $40 prize went to Lelsle Hennefer Tury of Springfield, Virginia, for a name taken from Jack Pearl's radio catchphrase, "Vas you dere, Sharlie?" Sightings ran through the Star-News for decades. In 1996 Kate Wolf of Boise followed humps across the lake in a pontoon boat. Today Sharlie appears in ice sculptures at the McCall Winter Carnival and on Sharlie Lane, and locals say Sharlie is female.