Walk along Damon Slough in Oakland and you’re likely to see trash heading towards San Francisco Bay. David Lewis of the environmental group Save the Bay, says much of it comes from the nearby 880 freeway and local storm drains.

“Every time it rains, anything that’s on the streets goes into the storm drains and straight out into the bay unfiltered. And we see this on all of the freeways and all of our urban road,” Lewis explains.