WASHINGTON:  The author of Washington’s recreational marijuana law has suggested that Spokane test its sewage for traces of the cannabis chemical THC, to get a more accurate picture of pot use by residents.

American Civil Liberties Union lawyer Alison Holcomb proposed the idea at a Tuesday meeting of the City Council’s marijuana policy subcommittee.

A scientist for the University of Washington said the proposal is a good idea.

“It’s always good for a chuckle, but it does actually work,” Caleb Banta-Green, a researcher at the University of Washington’s Alcohol and Drug Abuse Institute, said Wednesday.