The Ames Fire Department is closing it's investigation into a fire at a Brookside Park restroom even though the cause is unknown. The city says while the ignition source hasn't been determined, the investigation is complete. They also point out smoking isn't allowed in city parks and advise visitors using grills to douse coals and dispose of them in designated bins--not trash cans. The fire department says the fire, early Saturday morning, likely started in or around a trash can near the restroom before spreading to building's the wooden awning and roof. The city's put in portable toilets for park users. Damage is estimated at $50,000.