Source of contamination in smelly Thornton Creek a mystery

SEATTLE -- It’s not just a smelly problem but a potential public health hazard.

Scientists recently confirmed that Thornton Creek was polluted with human fecal matter. Concerned residents met with Seattle city officials on Thursday night to learn more about the dangers.

The creek runs more than 15 miles through King County. Many residents say they’ve always known this creek was polluted, but never thought human bacteria was in the mix.

Under a canopy of trees, the water flows -- it’s a scenic site for people who may not know what is lurking in Thornton creek.

“The contamination and all this stuff is new to us,” said Northgate neighborhood resident Glenn Hwaung.

Hwaung’s Northgate home borders Thornton Creek, and so do about 700 other back yards, many parks and even schools.

“I don’t think anybody ever expected this,” said Thornton Creek Alliance President Ruth Williams. Williams says it’s no secret most streams are polluted, but she thought the source was from animals, not humans.

“We know there is a problem, we just need to find where the problem is coming from,” said Seattle Public Utilities Stormwater scientist Jonathan Frodge.

Frodge detected the human bacteria after a two-year study.

“The health risk is higher,” said Frodge.

With that in mind, Frodge warned the community on Thursday not to touch the water.

“I think a leaky sewer system is a big part of the problem,” said Williams.

That is one possibility.

But scientists are also looking into whether people dumping from RVs and homeless encampments along the green belt are to blame.

“We’ve located a number of some of these sub-basins that are our prime suspects of where the sources could be and we are going to do some reconnaissance,” said Frodge.

Until then, the smelly creek is a mystery and the risk will flow all the way into Lake Washington and a small area of Matthews Beach Park, where many swim.

“If you are swimming in the mouth of the creek, the possibility you coming into contact with the bacteria is higher,” said Frodge.

Frodge says people should swim where the lifeguards are and stay away from where the creek meets the beach. The city will be monitoring Matthews Beach and plans to close it down if high levels of contaminants are detected. Back in Northgate, Hwaung says he will be more vigilant.

“We don’t let the kids or animals near the creek to play in the creek,” said Hwaung.

Besides human bacteria, e.coli was also detected. If you touch the water, wash your hands immediately with soap. The city says they will set up signs at different parts of the creek to warn people.