The Payette Lake monster ("Slimy Slim", later "Sharlie"): Dr. G. A. Taylor and about twenty witnesses, 1946

Payette Lake sits at McCall, in Valley County, west-central Idaho. Glaciers carved it. It covers nearly eight square miles and drops to 392 feet at its deepest point. Native American tradition spoke of an evil spirit that lurked in its hidden depths.

The modern stories began early. In 1917 or 1920, tie-cutters at the upper end of the lake saw a "log" that moved forward, began to undulate and created its own wake as it rapidly left the area. Then came July 2, 1944. Six people at Lakeview Camp, including Boise attorney Homer Martin, watched a creature moving through the water in an undulating fashion. By August, about 30 witnesses had come forward, and TIME carried the story. The lake's resident had a nickname. Slimy Slim.

September 1946. A group of about twenty people saw it on Payette Lake. Only one of them is named in the record. Dr. G. A. Taylor of Nampa.

Taylor tried to put numbers on what he saw. The creature appeared to be between 30 and 40 feet long. It left a wake "about like a small motor boat would make." And it would not stay on the surface. It seemed to keep diving into the water.

The Payette Lakes Star ran the report on 5 September 1946. The exact day of the sighting is not known, nor the spot on the shore. No colour, no head, no sound survives from Taylor's account. The camel humps and dinosaur head belong to the 1944 reports.

Taylor may not have been the only Nampa witness that year. In 2004, Nicholas Collias of Boise Weekly spoke with Milford Faylor of Nampa, then 86. His father, Milford Sr., was one of nine Nampans who saw Slimy at a lakeside cabin in 1946. The sighting made headlines in Nampa's Idaho Free Press and the Statesman. Whether those nine stood among Taylor's twenty, or watched on another day, no source says.

No official inquiry into the 1946 report is known. The science came later. In 1980, Gary S. Mangiacopra of Bloomsburg State College wrote a preliminary report on possible large animals in the Payette lakes. He argued the lake was too small to support a breeding population. In 1985, Idaho Fish and Game fisheries biologist Don Anderson said tests on the lake showed no evidence of a large serpent. Anderson did not close the door. "Maybe he's just smarter than us… I want him to be there, and if he is, we'll protect him."

Sceptics have offered several answers. White sturgeon could once swim up the Snake and Payette rivers, before the Snake River dams were built. They reach about eight feet and more than 300 pounds. A seiche, a standing wave raised by quick changes in air pressure, could throw up large waves mid-lake with no boat in sight. Floating logs have been suggested too. No hoax claim against Taylor or the 1946 witnesses has surfaced. No photograph or film of the creature exists.

In 1954 the Star News held a naming contest. LeIsle Hennefer Tury of Springfield, Virginia, won $40 for "Sharlie," a play on Jack Pearl's radio catchphrase "Vas you der, Sharlie?" Reports kept coming, from two Oregon anglers in 1947 to the 1990s. Today Sharlie appears in the McCall Winter Carnival parade, lends her name to a burger, and stars in Lynda Johnson's 2007 book and an episode of Astonishing Legends. The 1946 account remains one of her defining moments. Twenty people. Forty feet. A wake like a motorboat.