Sediments in the bottom of Central Puget Sound show declining environmental health over a 10-year period, according to a just-released report from the state Department of Ecology (Ecology). This is the area from Tacoma Narrows to Whidbey Island, including industrialized and urbanized Commencement Bay, Elliott Bay, Sinclair Inlet and Bainbridge Basin.

“The overall decline in sediment health is important because it is an indicator of the health of Puget Sound,” said Valerie Partridge, Ecology's lead author for the report.

The study also turned up good news. Central Sound sediments showed a decrease in concentrations of lead, mercury, silver, tin and polycyclic aromatic hydrocarbons. It also found that more samples are meeting state sediment quality standards in the heavily industrialized areas of Elliott and Commencement bays.

These trends suggest positive results from collective cleanups and pollution prevention efforts in those areas. The comparison found the decline in health of sediment-dwelling life – known as benthic invertebrates – had spread to 28 percent of the region, up from 7 percent. The decline could not be attributed to any significant chemical contamination that Ecology measured.

The report, “Sediment Quality in Central Puget Sound, Changes Over a Ten-Year Period,” compared sediment samples the state program collected in 2008 and 2009 to samples it collected in 1998 and 1999.

Ecology’s data and documentation can be found on Ecology’s marine sediment monitoring website.