A unique recycling program at Grand Canyon National Park is providing relief to area landfills — and tasty meals for the park's pack animals.

"Operation Shrivelly Apples" was conceived in 2013 by a staff member at a Canyon lodge. The staffer suggested that shriveled apples, which are unfit for human consumption, be fed to the mules that carry people down the Bright Angel Trail to the Colorado River and back.

The program has grown from there, Grand Canyon National Park Lodges said in a news release. Cooks at all South Rim restaurants now place discarded fruits and vegetables in buckets that are brought to the mules' stable. Veterinarians keep track of the scraps to ensure the mules are getting a healthy diet.

In 2014, the program diverted 30,000 pounds of food scraps from landfills, the release said. Additionally, the mules produced 1.5 million pounds of manure that was processed into compost. Operation Shrivelly Apples won the lodges an Environmental Achievement Award from the National Park Service last year.

The park plans to expand the program this year, adding composting trash cans in lodge rooms and bins where guests can toss their own apples, banana peels and other compostable items.