CHICAGO - JULY 30: Beachgoers play in the water at North Avenue Beach July 30, 2008 in Chicago, Illinois. According to the National Resources Defense Council (NRDC) beaches in Illinois have the highest number of water samples exceeding safe bacterial levels in the nation. (Photo by Scott Olson/Getty Images) (Photo by Scott Olson/Getty Images)

By John Dodge

CHICAGO (CBS) — After today, it will be illegal to swim in Lake Michigan until next May.

Officially, the Chicago Park District beach season started on May 23 and ends today.

That means anybody swimming in the lake starting tomorrow can be ticketed. The fine for any beach violation can be up to $500.

The ordinance is rarely enforced as the Chicago Police Department has plenty to deal with outside of strolling the beaches for scofflaws. However, if police are called to the scene (for example, a 911 call), a person is more likely to be fined.

According to Chapter 7 of the Chicago Park District code: “Entering or remaining in the water at [Chicago Park District] beaches shall be permitted only during the bathing season.” The part district does have the authority to extend the season.

Here are some other little-know rules about swimming in Lake Michigan.

> During the season, swimmers are only allowed to enter the water at the park district’s designated beaches:

> Swimmers must remain within 50 yards from shore

> Beach-goers cannot ride their bikes onto the beach.

> Artificial flotation devices, such as noodles or rafts, are not allowed. Coast Guard approved life jackets are permitted.

> “Unnecessary conversation” with a life guard is not allowed.