CHICAGO (CBS) — Organizers have called off the Red Bull Flugtag event, in which handmade gliders plummet into Lake Michigan, due to what they have termed “unsafe marine conditions.”

The event was planned for Saturday afternoon at the North Avenue Beach, but organizers had been considering canceling it due to low water levels in the lake.

On Saturday morning, organizers decided to go ahead with the cancellation, despite the large crowds that were expected.

In the annual Flugtag, dozens of daring divers in their handcrafted devices take a flying leap off a platform 30 feet in the sky.

For safe diving, the city wants 10 feet of water. But the runway at North Avenue has just 8 feet of water this year.

Lake Michigan, overall, is 10 inches lower than last year and 2 feet below the average level for September. In fact, CBS 2’s Ed Curran reports, the lake is just 6 inches away from the record low for September, set in 1964.

Contributing to the trend have been mild winters that don’t freeze the lake over, allowing more evaporation. Add to that widespread drought, an extremely hot summer, and you are taking water out of the lake faster than you can put it back in.

Flugtag events are still scheduled for Sept. 15 on the Camden Waterfront in Philadelphia, Nov. 3 at Bayfront Park in Miami, and Nov. 10 at McCovey Cove in San Francisco.

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