A boy who slid down into a drainage canal in Waipahu to retrieve his homework had to be rescued by firefighters Wednesday after he couldn’t climb back out, a fire department spokesman said.

The boy dropped his homework while crossing a foot bridge over the culvert and slid about 20 feet to the bottom of a steep cement embankment to get it, said Honolulu Fire Department Capt. Terry Seelig.

HFD workers were sent to the canal next to Waipahu Middle School about 2:10 p.m. after someone called for help for the boy, who is about 12.

Firefighters descended the cement embankment in a harness attached to a rope and helped the boy back to the top. He was out by 2:40 p.m., unhurt.

Seelig said people should stay out of the canal because several streams channel into it before heading out to Pearl Harbor and the tide also pushes water into it.

“It’s very dangerous and could turn into a very tragic situation if there’s a lot of water coming down,” he said.

The boy never got his homework back.