Human-caused ‘dead zones’ threaten health of Puget Sound

Wastewater treatment plants account for about 70% of the excess nutrients.

Budd Inlet, June 2018. Lisa Dennis-Perez, environmental planning and communications director for LOTT, said that estimates from the state thought roughly half of all nitrogen in Budd Inlet came from the wastewater discharge before LOTT was upgraded in the 1990s. Photo courtesy of Department of Ecology

Budd Inlet, June 2018. Lisa Dennis-Perez, environmental planning and communications director for LOTT, said that estimates from the state thought roughly half of all nitrogen in Budd Inlet came from the wastewater discharge before LOTT was upgraded in the 1990s. Photo courtesy of Department of Ecology

During the summer of 2015, thousands of dead eels washed up on the beaches of the Hood Canal. These eels suffered a familiar fate for marine life in many parts of Puget Sound and its long, shallow offshoots when the level of dissolved oxygen in the water had become too low to support them.

Elsewhere in Puget Sound, large blooms of algae or jellyfish can be seen drifting in the currents, especially during summer months. These floats indicate that there’s too many nutrients in the water. Algae thrive on these nutrients, and when they die and sink to the bottom, the bacteria that decompose them sucks up oxygen, leaving little for eels, fish and other animals.

One of the most common nutrients that boosts these algae blooms is nitrogen, and according to the Washington State Department of Ecology, wastewater treatment plants contribute significantly to low oxygen levels. Nitrogen in urine isn’t treated in most wastewater plants anywhere in Puget Sound, and King County’s West Point plant is one of the largest.

A 2019 report from the Salish Sea Model found that during the warm spring and summer months, wastewater treatment plants account for about 70% of the excess nutrients in Puget Sound. Much of the nitrogen in Puget Sound is from the Pacific Ocean, but human-caused nitrogen compounds this.

A 2011 Ecology study found that King County’s West Point and South Plant wastewater treatment plants were the two largest sources of human-caused nitrogen in Puget Sound.

Because of their concerns, Ecology decided in January 2020 to move forward with drafting a nutrients permit, specifically for filtering out nitrogen, that would be applied to the nearly 70 Puget Sound wastewater treatment plants.

“Municipalities have the responsibility to provide wastewater treatment to their residents, and also protect the environment,” said Eleanor Ott, Ecology’s permit lead for the proposed nitrogen project. “What we’re trying to do is ultimately prevent a dead zone from happening in Puget Sound.”

Dead zones are areas where there’s low levels of oxygen in the water. The second-largest dead zone in the world is located off the coast of the southern U.S. in the Gulf of Mexico.

Filtering for nitrogen

A stakeholders group representing environmental organizations, local governments and wastewater utilities met last year to discuss permit regulations. But there were disagreements on how quickly the permit should be implemented and its terms.

Utilities wanted longer implementation timelines, allowing them more than 10 years to begin filtering for nitrogen, while environmental groups said the regulations should be enacted sooner.

A majority of utility companies also won’t accept a permit that won’t allow them to use their full wastewater treatment capacity, or which requires them to deny new customer connections. Environmental groups and tribes insist that any discharge that increases from new connections must be offset by reducing the amount of water processed at a plant. This could mean building new wastewater plants to handle growing demand.

According to a King County Nitrogen Removal Study prepared last September, the cost of retrofitting wastewater treatment plants in the county would be expensive. How expensive depends on how strictly Ecology decides to regulate nitrogen.

At the West Point treatment plant, capital costs could range from as low as $89 million up to $2.9 billion, and cost between $1.9 million to $21 million to operate each year. The more nitrogen needing to be removed, the higher the costs.

But the less costly alternatives wouldn’t remove much nitrogen. The least expensive options would still leave 22 mg of nitrogen per liter of wastewater treated. Ecology could set targets as low as 3 mg to 10 mg of nitrogen per liter.

Christie True, King County’s Department of Natural Resources and Parks Director, said they expect Ecology to make a decision on the permit this year. Based on that, they will look at how to meet its conditions.

Ecology could allow the county to operate under a “bubble” permit, where the nitrogen emissions from all their plants would be wrapped under one permit. This would allow some plants, like West Point, which has little room for upgrades or expansions, to emit more nitrogen while other plants could be upgraded to more heavily filter the nutrient.

True said if they could spread out costs and upgrades over the next 15 to 20 years, the increase to ratepayers could be less than $10 a month for upgrades. But that price could rise to increasing monthly sewer rates 10 times what they are paying currently under faster timelines, she said.

“They’re quite substantial investments, and would take a long time to design and construct them,” True said. “I think just in terms of us looking at this, we think it’s really important that Ecology and the state gets the science right on this, and we’re absolutely certain that it will make a difference in the water quality of Puget Sound in areas where they’re experiencing low dissolved oxygen.”

True said she wants to ensure that nitrogen from their plants, which is discharged into central Puget Sound, is actually impacting shallow areas of the Sound.

Ecology Communications Manager Colleen Keltz said, however, that their 2019 Puget Sound Nutrient Source Reduction Project shows that nutrients move around Puget Sound. It’s the first phase of the Salish Sea Model, and confirms that wastewater treatment plants discharging into Puget Sound are contributing to dissolved oxygen in the Sound.

Fran Wilshusen is the Habitat Services Director for the Northwest Indian Fisheries Commission, an organization created by 20 Puget Sound tribes to provide direct support for access to fish and management. Treaties between the federal government and these tribes ensure they will have access to their usual and accustomed fishing areas. A dead zone in Puget Sound would be a breach of those treaties.

“Things like environmental degradation have an immediate impact on how many fish there are to be harvested,” Wilshusen said.

Ecology pushing for a nitrogen wastewater permit is the state understanding and acting on the science, she said. And she expects resistance from utility providers.

“It’s just the way we do things if you’re the now local government wastewater treatment facility, that has to come into full compliance, it’s hard,” she said. “And not only that, it’s expensive. So they’re going to push back.”

Puget Sound residents have a history of paying for measures that protect the natural beauty and health of their waters, Wilshusen said. For her, it’s a matter of highlighting to people the importance of these kinds of permits for wildlife and the ecosystem.

There is one wastewater treatment plant in Puget Sound that does treat for nitrogen. The LOTT Clean Water Alliance plant in Olympia began removing nitrogen in the early 1990s, at the direction of Ecology. Lisa Dennis-Perez, environmental planning and communications director for LOTT, said that estimates from the state showed roughly half of all nitrogen in Budd Inlet came from the wastewater discharge before the plant was upgraded.

In 1996, the state issued permits, allowing a maximum of 3 mg of nitrogen per liter. This was later made more stringent in 2005, when the state added a limit to the total amount of nitrogen that could be discharged per day. While this poses operational challenges, Dennis-Perez said it’s worth it.

“Our job is to clean water and to protect public health and the environment. That is our mission,” she said.


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