The Washington State Department of Ecology is asking for public review and comment on a draft permit aimed at better controlling nutrients that wastewater treatment plants — including the City of Edmonds plant — discharge directly into Puget Sound. Virtual information sessions are also scheduled this Tuesday and Wednesday, Feb. 9-10. (More details below.)
The Puget Sound Nutrient General Permit applies to nearly 60 treatment plants that discharge directly to Puget Sound and its estuaries. All of the facilities already have individual National Pollutant Discharge Elimination System (NPDES) water quality permits that include a wide range of requirements to protect water quality. However, only a few of these NPDES permits currently require nutrient controls. The new general permit will focus only on controlling nutrients and work in conjunction with the broader individual permits for each facility, the Ecology Department says.
“The informal draft is conceptual and does not have as much detail as the formal draft and final permits will include,” Ecology says in a post on its Ecology Blog. “Given the complexities of this permit and the critical services sewage treatment plants provide, we are offering multiple opportunities for stakeholder input as we develop the permit.”
The informal draft was prepared, Ecology says, after working with an advisory committee comprised of regional wastewater treatment plant representatives, state agencies (including Ecology and the Department of Commerce), the U.S. Environmental Protection Agency, and the environmental community.
City of Edmonds Public Works and Utilities Director Phil Williams says that the permit will cover an upcoming five-year period and requires the city to collect “a significant amount of new monitoring for Total Inorganic Nitrogen (TIN), and Total Organic Nitrogen (TKN) in our discharge to Puget Sound during that time. It also asks us to ‘optimize’ our plant to reduce, as best we can, without incurring large, new expenses, the amount of TIN/TKN discharged.”
The Ecology Department notes that nutrients are an important part of a healthy marine ecosystem, but excess nutrients cause too much algal growth, which ultimately depletes dissolved oxygen (DO) in the water. This algal growth occurs because nutrients are fertilizer for algae and aquatic plants. When these algae and plants die, their decomposition uses up oxygen. Many parts of Puget Sound and the Salish Sea have dissolved oxygen levels that fall below the concentrations needed for marine life to thrive. In addition to low levels of oxygen, effects of excess nutrients include:
- Increasing the acidity of the water
- Shifts in the food web
- Increases in harmful algal blooms and nuisance species like jellyfish
These issues are directly related to supporting a healthy ecosystem for salmon and orca recovery, Ecology says. “Science tells us that excess nutrients from…