Dan Burgard, an associate chemistry professor at the University of Puget Sound and lead on the project, told Phys.org that he and his team are trying to get a sense of the type of user.
"If there's more use on the weekends, maybe that's more recreational," he said. "But if Sunday to Thursday use goes up as much, that might be a public health concern, with habitual users using a lot more."
The data could also show whether people are buying their marijuana from stores or on the black market by comparing wastewater marijuana levels to sales figures.
The two cities being tested will not be announced until project completion.
