Puget Sound is full of old tires... on purpose?

Decades ago, states began putting bundles of tires on the seafloor as "artificial reefs." Their aim was to build new habitats for local marine life. Today, there's little proof these tires are serving their intended purpose.

So whose job is it to pull these tens of thousands of tires back up?

Artificial reefs can come in all different shapes and sizes. At Saltwater State Park, just outside Des Moines, local scuba enthusiasts installed a three-tiered rock reef. Anemones love to attach themselves to these structures, and octopuses find comfort in their dark crevices.

But the materials used for these reefs vary widely, and the science on their impact to local ecosystems is still developing.

"The state and other organizations decided way back when, in the early 70s and 80s, that, hey, we can put out all these bundles of used tires... and things will grow on them, and it will be great artificial reef," said Randy Williams, vice president of the Washington Scuba Alliance. "Wrong. It didn't work."

One concern with these tire bundles is a chemical known as 6PPD-quinone, which is a byproduct of an additive used in tires to prevent cracking and general wear and tear on our tires. Research from teams at the University of Washington and Washington State University shows the chemical can shed from tires in the form of dust, which when combined with storm drain runoff, is harmful to coho and Chinook salmon. Though, further research needs to be done on seafloor tires to determine the presence and impact of PPD6-quinone.

The Washington Scuba Alliance has been the point organization helping scan and identify these bundles on the Puget Sound seafloor. At the current count, Williams says they've found more than 26,000 tires, with estimates that there could be around half a million across the region.

You can hear Soundside's full conversation with Randy Williams by clicking the audio above.