The state Department of Ecology released the first part of a water quality study on the impact and sources of low dissolved oxygen levels in South Puget Sound.  They summarize the need for the study.  "Marine animals need oxygen to live . . . In areas with low levels of dissolved oxygen, fish and other marine life become stressed and die or are forced to flee their habitat. There are many areas in Puget Sound with very low levels of dissolved oxygen . . . In Hood Canal, low levels of dissolved oxygen have caused major fish kills. The rest of Puget Sound (especially areas in South Puget Sound) faces the same fate unless we work to solve the problem."

The study identifies nitrogen as the main pollutant that causes low dissolved oxygen levels.  "Discharges from wastewater treatment plants, septic systems and other sources add nitrogen to Puget Sound. Excess nitrogen causes excess algae growth. As the algae dies and decays, they rob the water of dissolved oxygen. Once released into Puget Sound, nitrogen moves around.  Nitrogen discharged at one spot may cause low dissolved oxygen levels many miles away."

This study is a critical first step, sampling waters from King to Mason counties.  The findings: there are many areas of Puget Sound with very low levels of dissolved oxygen.   In Hood Canal, low levels of dissolved oxygen have already caused major fish kills.  The rest of Puget Sound, particularly in the South Sound, faces the same fate unless the problem is solved.   The next part of the study is an analysis "of how water circulates in Puget Sound, how nitrogen is affecting the water quality and what to do about it."

"Nitrogen is the main pollutant that causes low dissolved oxygen levels: Discharges from wastewater treatment plants, septic systems and other sources add nitrogen to Puget Sound. Excess nitrogen causes excess algae growth. As the algae dies and decays, they rob the water of dissolved oxygen. Once released into Puget Sound, nitrogen moves around.  Nitrogen discharged at one spot may cause low dissolved oxygen levels many miles away."

In an article on the study in the Seattle Times, Lynda Mapes, the reporter, says, "So far scientists have found sewage-treatment-plant pipes contribute 80 to 90 percent of the nitrogen in some parts of Puget Sound during some parts of the year, according to the study . . . How a complex system such as Puget Sound, with its differing depths and circulation patterns can be best managed for water quality is something scientists are still working to figure out . . . More study can help target places where the combination of nitrogen loads and local circulation patterns and weather combine to harm aquatic life.

"When it's complete in 2010, the study may help target where and how to make smart investments in water-quality improvement, said Duane Fagergren of the Puget Sound Partnership, the new state agency created to protect and restore Puget Sound. Fagergren said."