San Mateo Water Quality Has Gone to the Dogs

Bacteria from unattended dog waste contaminates local beaches


Sometimes being at the top is the last place you want to be. San Mateo County learned that lesson recently when a study by the Natural Resources Defense Council found that our local beaches have the second highest level of bacteria in California. One of the suspects? Your pooch. Or more specifically, your pooch’s poop.


Unsightly and Unsafe


We all know how unpleasant it is to mistakenly step in a pile of dog waste that has been left behind on the sidewalk. That unattended pile of poop also poses a threat to our waterways. Research has shown that dog waste from residential neighborhoods—miles away from the coast—is causing the amount of bacteria in waterways and the ocean to spike. 


Pet waste contains a host of bacteria, viruses, and pathogens, which migrate through storm drains to local rivers, the bay, and the ocean. High levels of bacteria make the water unsafe for swimming and hazardous to the fish and wildlife that rely on the waterways for food and shelter.


Biodegrade or Bust


Many people assume their dog’s waste will eventually biodegrade. But decaying poop that makes its way into the bay actually eats up oxygen and releases ammonia, which can disturb the underwater ecosystem and damage the health of fish and marine life.


And while no one dog is to blame, the more dog waste that’s left behind the more serious the problem becomes. “When one dog owner leaves waste behind it isn’t a big deal,” says Matt Fabry of the San Mateo Countywide Water Pollution Prevention Program. “However, if half of all San Mateo County dog owners are leaving waste behind, it becomes a big deal. Bacteria from dog waste are impacting harbor seals right here in San Mateo County.”


What You Can Do 


Always carry a bag with you on walks and pick up after your pet. Just be sure to dispose of the bag in the trash. Dog waste left in bags on the street also washes into storm drains. Dog owners in need of bags can email for more information.


Free Dog Bag Dispenser Giveaway!


Carry your doggie bags in style. San Mateo County is giving residents a free dog bag dispenser with carabiner for easy clipping onto a leash or belt loop. Available to San Mateo County residents only, while supplies last. Email