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Counties Deploying Bacteria-Sniffing Dogs To Find Failing Septic Systems

Chris Kittredge Photo
Molly, a border collie trained by Environmental Canine Services, can sniff out human fecal coliform bacteria in water samples. She recently worked for King County at creeks in Seattle and Kirkland.

In recent years, the Samish River Basin in Skagit County has suffered severe pollution from fecal coliform bacteria. Water polluted with untreated sewage and manure leads to frequent closures of shellfish beds and beaches. County authorities are testing a new method to find the sources: poop-sniffing dogs

In the parking lot behind Skagit County offices, a dog named Crush recently ran between buckets filled with water samples. She passed over most of them, but would stop and lie down by a few. She’s trained to detect pollution in the form of human fecal coliform only.

“And so in those locations where the dog detects human sewage, we have pretty good evidence that there must be a failing septic system nearby,” said Rick Haley, a water quality analyst for Skagit County Public Works.

Haley says the utility has worked hard with livestock growers in recent years to reduce pollution from manure runoff. Deploying the dog, brought in with her handler from a company in California, should help them pinpoint more leaky septic tanks or other sources of human fecal pollution.

“Their noses are really sensitive, and it seemed reliable. It passed all the quality control tests with flying colors,” Haley said.

After the bucket tests in the parking lot, crews took Crush out in the field where she led them to more precise locations. Most were streams and ditches where they already suspected water pollution.

Haley says using the dog may be more effective than chemical tests, which provide less immediate results and aren’t necessarily reliable.

King County also recently deployed Crush and another dog named Molly, in Seattle’s Thorton Creek and Juanita Creek in Kirkland.

Bellamy Pailthorp covers the environment for KNKX with an emphasis on climate justice, human health and food sovereignty. She enjoys reporting about how we will power our future while maintaining healthy cultures and livable cities. Story tips can be sent to