A few years back, while joining a group cleaning up an area at the confluence of the Scioto and Olentangy rivers, Leslie Strader found a stuffed SpongeBob SquarePants doll floating in the water.

A few years back, while joining a group cleaning up an area at the confluence of the Scioto and Olentangy rivers, Leslie Strader found a stuffed SpongeBob SquarePants doll floating in the water.

"We all kind of got a good chuckle out of that," said Strader, volunteer services manager for the Columbus Recreation and Parks Department.

At another cleanup in Dodge Park, Strader's group found a safe that had been hacked open.

"You can find just about anything out there, sadly," she said.

But in a new contest sponsored by the city of Columbus and the Solid Waste Authority of Central Ohio, only the strange will do.

The two are sponsoring the Strange Litter contest, in which participants in permitted cleanup events are encouraged to photograph the most outrageous piece of trash they can find.

Those who find the most bizarre pieces of litter will be awarded prizes -- $75 gift card for first place, $50 for second place and $25 for third.

The contest is open through noon Aug. 31.

Through the city's website at columbus.gov/CRPDvolunteers, volunteers can join a public cleanup or schedule and event at the park of their choice by completing a proposal form.

The website features a map of park locations and their status.

The city provides park access permits, trash bags, gloves and waste hauling to support volunteer group efforts to remove litter from parkland.

There are some rules to the contest. The city will not accept, for example, photos that contain explicit, obscene, violent or other objectionable or inappropriate content, or images that depict any violations of law or park rules. In other words, pictures should be of non-natural pieces of litter, Strader said.

Strader said the goal is to have littler removed at least once a year from every park.

"We want to stay on top of it because it can accumulate if we don't," she said.

David Roseman, a member of Friends of Alum Creek and Tributaries, said he's seen a lot of oddball items in his 100-plus cleanups over 10 years: 800 tires, railroad ties, shopping carts, and two automobiles frames, which could not be removed.

"We literally have pulled out the kitchen sink," he said.

But it's the mundane litter -- pop cans, water bottles and plastic bags -- that keeps clean-up groups busy year-round, Roseman said.

"We're doing the best that we can," he said.