sewers

Seattle pledges more pollution control to help Puget Sound

The city of Seattle and King County will step up efforts to prevent raw sewage from flowing into Puget Sound and its tributaries, the U.S. Environmental Protection Agency announced today.

But the steps are small compared to those called for by environmentalists who want to see Puget Sound and the Duwamish River cleaned up. The current schedule gives Seattle until 2020 and King County until 2030 to almost completely end pollution from so-called "combined sewer overflows." (PDF)

These sometimes-smelly oopsies result from a piping system that mixes untreated sewage with rainwater runoff. Most of the time it's a good system because the rainwater -- aka stormwater, the largest remaining water pollution source in the country -- goes to a wastewater treatment plant.

But when a lot of rain hits overloaded systems like the one King County and Seattle operate, the whole mess comes shooting out into waterways. Sometimes the stuff backs up into streets or even basements.

Major pollution discharges into the Duwamish River are scheduled to continue for decades, despite today's order and despite what's supposed to be a  major EPA effort to clean up the Duwamish.

Such discharges happened 336 times in the Seattle-King County system in 2007, the most recent figures available.

A surprising number of these overflows happen during relatively dry periods after little or no rain.