ALPHARETTA -- Park rangers are asking for help in tracking down whoever dumped stacks of tires at a park along the Chattahoochee River.

Someone dumped more than 50 tires in the creek that runs through the Jones Bridge Unit of the Chattahoochee River National Recreation Area. That section of the park is located on Barnwell Road in Alpharetta.

Rangers say the tires were tossed into the creek in three separate incidents on June 7, 8 and 9.

They are concerned the tires could contaminate Atlanta's drinking water.

"This is water that we end up using; playing and drinking and now we have 52 tires sitting in this water," said Ranger Melissa Lanshe.

The Park Service is offering a $250 reward for information on anyone dumping trash in the park.