A grand plan to reduce human sources of nitrogen in Puget Sound started coming into focus in 2019 when the issue of regulations reached a decisive point.
After years of study and advances in computer modeling, experts at the Washington Department of Ecology were beginning to see what it would take to reduce human sources of nitrogen and improve oxygen conditions harming sea life. But key questions remained: How would the state agency go about getting sewage-treatment plants to reduce their nitrogen releases, and what could anyone do to address the multitude of upstream sources of nitrogen washing off the land?
The answers have come with some resistance, scientific skirmishes and legal entanglements — and many issues remain unresolved today. For example, uncertainty surrounds new permits for sewage-treatment plants because of recent court rulings. Meanwhile, today, Ecology released its long-awaited plan for reducing nitrogen coming into Puget Sound from both point and nonpoint sources.
Nutrient general permit
In January 2020, Ecology announced that it would develop a “nutrient general permit” for all sewage systems discharging directly into Puget Sound. The new permit would address nitrogen and would be in addition to existing individual permits that set limits on other forms of pollution. The general permit would require monitoring of nitrogen discharges, planning efforts to reduce nitrogen releases, and eventually numeric limits for nitrogen in effluent.
Leading up to the decision, Ecology received mixed support for the idea of a general permit. Treatment plant operators — including cities, counties and sewer districts — were generally skeptical and expressed concerns about complying with two major permits. They wanted to make sure that any decisions would be based on solid science and allow time for implementation. Environmental groups and many individuals strongly supported the general permit — or practically any measures that would bring quick action.
After deciding to create a general permit, Ecology called together experts and formed the Nutrient General Permit Advisory Committee to help draft the parameters of the new permit. Individuals affiliated with wastewater facilities, environmental groups, state and federal agencies and a tribal utility were among the members working together through much of 2020. Their recommendations, issued in October that year, were far from unanimous.
While most everyone agreed that planning should take place at the local level, differences of opinion developed between representatives of the environmental community and officials managing sewer utilities. The greatest divide related to placing numeric limits on nitrogen releases and on a schedule for planning, engineering and equipment upgrades to meet stricter standards, whatever they might be.
There was some agreement that “optimization,” — making relatively minor changes to current facilities — could help control nitrogen without the expense of full-blown nitrogen-removal systems. But federal and state officials said optimization alone would not be enough to meet Puget Sound’s water-quality standards, based on outputs from computer modeling.
On Dec. 1, 2021, following two public comment periods, Ecology approved the general permit, which divides 58 treatment plants into three categories, dominant, moderate and small nitrogen dischargers. Together, the dominant dischargers release more than 99 percent of the total nitrogen from treatment plants, and they would be asked to do the most.
In the beginning, the general permit allows the plants to maintain their current nitrogen releases with careful monitoring as they optimize their existing facilities. The permit also includes “nutrient action levels” that would trigger further reduction efforts when nitrogen releases exceed their current levels by specific amounts.
Legal entanglements
Within a month of permit approval, eight sewage-treatment plant owners filed appeals with the state Pollution Control Hearings Board, which consolidated the appeals into one case. Plaintiffs included King and Pierce counties; the cities of Tacoma, Everett, Bremerton and Edmonds; and the Alderwood and Birch Bay sewer districts. These entities argued that the general permit is unlawful because treatment systems already have individual permits to govern their discharges, and the law does not allow a general permit to override an individual permit.
On the opposite side of the issue, Puget Soundkeeper Alliance, Washington Environmental Council (now Washington Conservation Action) and the Suquamish Tribe also filed appeals, saying the general permit did not go far enough or fast enough in reducing nitrogen going into Puget Sound.
If things weren’t complicated enough, another lawsuit filed by the city of Tacoma was making its way through the courts. Tacoma officials argued that Ecology had not followed proper procedures in creating a new rule regarding nutrient limits. This took place at an earlier time, before the general permit came into play, and Ecology insisted that it had not created any new rules at that time.
The Tacoma case, joined by other sewer utilities, focused on a letter issued by Ecology when it turned down a petition from Northwest Environmental Advocates asking Ecology to require nitrogen-removing equipment at all treatment plants in Puget Sound. NWEA cited state law that requires the use of “all known, available and reasonable technology (AKART).” The organization said advance treatment capable of removing nitrogen — so-called tertiary treatment — was “known, available and reasonable” and should be used everywhere. Ecology’s letter said that AKART does not apply to the current situation, because tertiary treatment is not reasonable, given the high costs and lack of evidence that high-level treatment is needed everywhere throughout Puget Sound. (This issue was covered in part 2 of this series.)
In turning down the AKART petition, the letter noted that Ecology was taking “alternative measures” to address the low-oxygen problem — including setting nutrient limits at existing levels and requiring treatment plants to plan for further decreases in nitrogen. Tacoma’s attorneys argued that such commitments without a public process amounted to unlawful rulemaking. As such, Ecology should be prevented from limiting nitrogen levels until going through proper procedures, according to the lawsuit.
The Suquamish and Squaxin Island tribes filed a brief supporting Ecology and stressing that their treaties with the federal government establish legal rights to harvest fish and shellfish. Such rights, they said, are diminished by poor water quality and delays in addressing the problem. Washington Environmental Council took part in that brief.
The case worked its way up to the State Supreme Court, which eventually ruled last year (PDF) that Ecology’s letter was not a formal commitment to limiting nitrogen levels, so it did not amount to rulemaking. Although the parties had agreed that monitoring and planning should move forward under the general permit, the Tacoma lawsuit effectively halted the appeals of the general permit for two years.
Last December, the Pollution Control Hearings Board restarted the appeal process for the general permit. Based on an extensive review and citations of state law, the board ruled (PDF) that Ecology cannot require a general permit if a sewage-treatment facility already has an individual permit for controlling pollution. The general permit could go forward as written, however, provided it becomes voluntary on the part of sewer utilities.
Ecology chose not to appeal the matter to the courts. Instead, the agency decided to keep the general permit for facilities voluntarily choosing to take advantage of the permit’s special “flexibility” and “regional approach” to addressing the nitrogen problem. For those entities that choose not to opt in to the general permit, Ecology intends to add new nitrogen-related requirements to existing individual permits, including possible administrative orders to require ongoing monitoring and evaluations, such as those under the general permit. See letter to permittees (PDF).
“We don’t know how many people will opt in, but we think it is important to keep the regional approach on the table,” said Vince McGowan, manager of Ecology’s Water Quality Program at the time.
For one thing, flexibility in the general permit could allow “nutrient trading” — the idea that greater nitrogen reduction at one treatment plant could offset less reduction at another plant, while still meeting water-quality goals, he said. This market-based approach offers a strong incentive to shift costs and save money. This could happen if upgrading an old plant is unreasonable or when a new plant could be efficiently expanded beyond its immediate need.
In its ruling, the Pollution Control Hearings Board said if Ecology truly believes that two permits should be mandated, the Legislature could change the state law. Ecology officials say they have not decided whether they will ask the Legislature for such a change.
Costs and financial challenges
One of the big issues looming over the entire planning effort is the significant costs of adding entirely new treatment processes to already complex facilities designed to remove organic materials from sewage effluent.
Everybody wants to know what nitrogen removal will cost overall and how it will affect sewer bills. Answers about costs vary greatly, depending on the levels of nitrogen removal and the equipment required to meet water-quality goals at a specific location, as predicted by computer models.
In 2023, Susan Burke, an economics professor at Western Washington University, worked with other researchers to examine questions of cost and affordability to Puget Sound sewer customers who will ultimately pay some or all the costs of nitrogen reduction.
“Capital costs associated with adding advanced nutrient removal technologies to all the municipal wastewater treatment plants subject to the Puget Sound Nutrient General Permit are likely to exceed $2 billion, based on a preliminary economic evaluation of potential nutrient limits by Ecology and Tetra Tech (2011) escalated to 2022 dollars,” states the “Puget Sound Wastewater Service Affordability Analysis.”
The report acknowledges that such estimates are “very low,” based on newer information, but they provide a starting point for discussions. In fact, some officials contend the ultimate costs may be many times higher than the range suggested by Tetra Tech in its 2011 report.
The Burke study analyzes the effect of higher sewer rates on 80 utilities around Puget Sound that could be affected by the cost of new nitrogen-removal equipment and ongoing operating costs, including increased electrical consumption.
“Current monthly sewer bills range from $27 to $161,” the report states. Changes anticipated under the Puget Sound Nutrient General Permit (PSNGP) could bring monthly sewer bills to between $44 and $196, “depending on the utility and the nutrient-reduction scenario.”
Considering a family’s ability to pay higher sewer bills, the study concluded that affordability could be an issue for many households in the lowest-income group, which is 20 percent of the population. This is described as the lowest quintile income, or LQI. Future bills could average about 4.4 percent of household income in that group, or just under half of what those families spend on food, based on national statistics.
“Our findings suggest that currently only three Puget Sound utilities’ sewer rates result in sewer bills less than 2.0 percent of LQI,” the report states. “PSNGP-adjusted rates resulted in values ranging between 2.64 percent of LQI and 12.76 percent of LQI. These relatively high values indicate that sewer bills exacerbate the already regressive nature of Washington state’s tax structure.”
Grants and loans to sewer utilities could help reduce the overall costs borne by ratepayers, the report says, and data about the number of low-income sewer customers in specific areas could help direct those dollars to families with the greatest need. A more-direct effect would be a “low-income assistance program to aid those with the greatest need.” Burke is conducting another study looking at a specific type of low-income assistance program, this one under contract with the Washington State Department of Health.
Reducing nitrogen upstream
Computer modeling and ongoing discussions among experts have concluded that, beyond improvements to sewage-treatment plants, major reductions in nitrogen must also occur upstream across the landscape to improve dissolved oxygen conditions in Puget Sound.
As described in part 3 of this series, nitrogen delivered to Puget Sound in major rivers originate from a variety of sources as unique as the surrounding land uses. While computer models help establish nitrogen-reduction goals, they don’t offer prescriptions for accomplishing those goals. Reducing such diverse, nonpoint sources will require a wide-ranging strategy that accounts for the diversity of sources, as described in the “Draft Implementation Strategy to Improve and Protect Puget Sound Marine Water Quality and Dissolved Oxygen.”
“Based on the available science and modeling on nitrogen in Puget Sound, human nitrogen source reductions are needed from both point and nonpoint sources in nearly every Puget Sound watershed to improve the DO indicator and meet water quality standards,” states the draft implementation strategy released in February under the purview of the Puget Sound Partnership, the state agency leading Puget Sound recovery.
The strategy, developed by specialized teams including more than 40 experts, was designed to help the region reduce nitrogen and thereby improve the health of Puget Sound. The best suggestions to emerge after further planning are expected to be incorporated into the Puget Sound Action Agenda for prioritized funding.
In addition to the implementation strategy, information on reducing upstream sources of nitrogen is provided in Ecology’s “Water Quality Management Plan to Control Nonpoint Sources of Pollution.” The plan, first adopted in 2015, is currently undergoing revisions, and public comments will be taken until Aug. 29.
Some of the specific ideas for watersheds, covered in these and other documents:
Pollution Identification and Correction (PIC) programs: Long used by some jurisdictions to track down sources of bacterial pollution, PIC programs could be employed to locate the most significant sources of nitrogen in a watershed. Water-quality inspectors typically start at one location in a stream and work their way upstream, taking water samples to identify tributaries delivering the most pollution, then moving farther upstream in search of the source or sources.
Agricultural runoff, primarily crop fertilizers and livestock wastes: The federal Clean Water Act does not address agricultural pollution, but Washington state law prohibits the discharge of any materials that contribute to pollution. “Best management practices,” or BMPs, have been designed to help farmers apply appropriate amounts of fertilizer and to reduce runoff from pastures, livestock-confinement areas and manure storage. Local conservation districts often provide advice to farmers, and grants may be available to help with the expenses of carrying out BMPs and other voluntary actions.
Urban stormwater runoff: Nitrogen from lawn fertilizers, pet wastes, wild animals, sewage spills and other sources may wash off the land and into nearby streams, eventually reaching Puget Sound. Methods of containing and infiltrating rainwater into the ground can help keep surface flows from picking up pollution. Commercial stormwater permits may include controls to reduce pollution leaving a property. Municipal stormwater permits, which address runoff from streets and other hard surfaces, may include requirements for source control, water treatment, system maintenance, public education and pollutant limitations. New innovations for onsite nitrogen removal may be required.
Forestry practices: Removal of trees and vegetation along streams can lead to increased water temperatures and greater sedimentation. Warmer waters have less oxygen-carrying capacity, and sedimentation can add nitrogen, phosphorus and organic materials that can reduce oxygen levels. Red alder trees, one of the first species to colonize disturbed areas, can contribute to increased nitrogen, because their roots play host to bacteria that fix nitrogen from the air and release it into the soil. Managed forests may include chemical fertilizers or biosolids from sewage-treatment plants. Maintaining and adding trees to stream buffers have been shown to improve temperatures and reduce nitrogen and other pollutants. Specific strategies for reducing nitrogen from alder trees are under discussion.
Natural nitrogen attenuation: Nitrogen- or phosphate-laden waters that flow through vegetation can reduce their nutrient loads by effectively fertilizing the plants. The vegetation can be part of a natural area or be incorporated into an artificial stormwater system. Maintaining natural vegetation and wetlands can reduce nutrient loads. Artificial systems often require regular maintenance to remove built-up sediment and excessive plant growth.
Septic systems: In areas without sewers, septic systems are designed to separate solids from liquids and discharge nitrogen-containing effluent into adjoining drainfields. Malfunctioning systems may release excess nitrogen into surface water or groundwater. Although functioning septic systems can theoretically release nitrogen into local waterways, studies have shown that properly maintained systems are not a significant problem. State regulations require regular septic inspections to ensure proper functioning, although enforcement varies among local health jurisdictions.
Challenges to restoration
Controlling upstream sources of nitrogen can be challenging, depending on the source, as we know from experiences elsewhere in the country and across the globe. Overall goals for the east side of Puget Sound may include more than a 60 percent reduction in nitrogen loads, according to recent information from Ecology.
Nitrogen coming into Puget Sound with the rivers consists of a large variety of upstream sources with amounts unique to each river: sewage treatment plants, agricultural operations, urban runoff, alder trees and more. Taken together for all of Puget Sound, sewage treatment plants account for more than a third of the total nitrogen coming into Puget Sound from the watersheds, followed by alder trees with about 15 percent. Farm operations, urban runoff, atmospheric deposition and septic systems are each under 10 percent of the total — although, again, sources in one watershed vary significantly from any other watershed. These numbers were calculated using modeling data reported by Noah Schmadel and colleagues at the U.S. Geological Survey.
While conditions are significantly different in Chesapeake Bay on the East Coast, a 40-year struggle to reduce low-oxygen problems in the bay may offer lessons for Puget Sound. Nitrogen inputs to the bay have been reduced since 1985 in the face of a rapidly growing population, yet the region remains far short of its goals to restore the waterway, according to a 2023 study by the Scientific and Technical Advisory Committee (PDF),, made up of 10 experts from five states, one from the District of Columbia, six from the federal government, and 21 at-large members, mostly from universities and research institutions.
The report says nitrogen from nonpoint sources was reduced by 29 million pounds from 1985 to 2022, yet that is just 36 percent of the long-range goal of 80 million pounds.
“Achieving nonpoint source reductions has proven more challenging than anticipated when the first nutrient reductions targets were established in the early 1990s,” the report says. “The challenge is twofold. First, voluntary nonpoint source programs struggle to produce the scale of behavioral change and practice adoption necessary to achieve water quality goals — an implementation gap. Second, the nonpoint source programs and practices implemented may not be as effective as expected at reducing nonpoint source pollution —a response gap.”
Despite increases in population, nitrogen discharges from sewage-treatment plants were reduced by about 50 percent from 1985 to 2017, thanks mainly to advances in treatment technology, according to a U.S. Geological Survey report titled “Nitrogen in the Chesapeake Bay Watershed: A Century of Change, 1950–2050.” While nitrogen reduction will continue, officials say, dramatic reductions from treatment plants and other point sources are unlikely.
“Although implementation of urban management practices to reduce nonpoint sources of nitrogen (such as stormwater) will continue with new development, the potential nutrient reductions of those practices in the future are uncertain,” the report says.
For decades, agriculture has played a prominent role in the low-oxygen problem in the Chesapeake, releasing more nitrogen and phosphorus than any other source. State and local governments have invested heavily in programs to reduce nitrogen from farms, but improvements have been slow, officials say.
Much of the agriculture in the Chesapeake watershed lies on the fertile coastal plain on the eastern shore of the bay and in southeastern Pennsylvania, the report notes. “Unfortunately, many of these regions also tend to have geologic settings (for example, sand/gravel, carbonate aquifers) that facilitate nutrient transport to groundwater and eventually streams.”
Reductions in nitrogen were attributed largely to conservation practices, such farmland retirement, animal waste management systems, and conservation tillage, but also bioretention by ponds and wetlands, the report says.
The ecological response to these efforts, such as water quality in the bay, appear to be delayed, as it takes time for existing nitrogen to work its way through the system, according to the report.
“Can the Chesapeake Bay, and similar estuary communities around the world, find ways to flourish and live sustainably, while at the same time managing nutrients that maintain healthy terrestrial and aquatic ecosystems?” the authors ask. “This” they add, “will be a challenge for the future.”
Climate change and future conditions
Climate change is expected to reduce dissolved oxygen levels in some parts of Puget Sound as a result of multiple factors, including warming waters, alterations in streamflow and potentially greater amounts of nitrogen coming in from the Pacific Ocean, according to experts.
Depending on the location, Puget Sound waters have increased by 0.8 to 1.6 degrees F between 1950 and 2009, according to localized studies, and this trend is likely to continue or even accelerate as a result of climate change. Warmer water cannot hold as much oxygen as cooler water, so this factor alone could increase stresses on marine life.
Puget Sound also is influenced by incoming flows from the Pacific Ocean, where oxygen levels declined roughly 22 percent from 1956 to 2006 at Ocean Station Papa, a weather buoy about 640 miles off the coast of British Columbia. Similar declines have been measured in the Strait of Georgia north of Puget Sound, primarily from coastal upwelling of low oxygen water from the deep. Consistent trends have been measured in Washington’s Strait of Juan de Fuca, Admiralty Inlet and Hood Canal, suggesting that oceanic conditions could add to future low-oxygen problems in Puget Sound. See “State of Knowledge: Climate Change in Puget Sound.”
Climate change is expected to continue an ongoing shift to earlier-in-the-year snowmelt in the mountains, with higher winter streamflows and lower summer streamflows expected over time. These alterations in flow patterns affect both stratification (layering, with freshwater typically on top) and circulation, two major factors that help determine oxygen levels. But neither the precise conditions nor the effects on oxygen levels can be predicted, according to the Climate Impacts Group, a University of Washington program that produced the State of Knowledge report.
“Stratification inhibits mixing of deeper, nutrient-rich water up into the zone where there is enough light for photosynthetic organisms (e.g. algae) to grow and favors the formation of low-oxygen zones at depth,” the report states. “In winter, this is not a major limitation, since the main impediment to biological productivity is a lack of sunlight. During the growing season, in contrast, water column stratification can potentially limit the supply of nutrients to phytoplankton and the supply of oxygen to deeper waters.”
A 2014 Ecology report, titled “Puget Sound and Straits Dissolved Oxygen Assessment,” analyzes impacts of human nitrogen sources along with climate change to the year 2070.
“Stratification overall appears to be strengthening, which could contribute to the downward trend in oxygen,” states the report. “The change in stratification from both salinity and temperature changes would also affect circulation. This assessment focuses on changes in DO and nitrogen alone, but additional analyses are needed that also incorporate changes in temperature and salinity at the ocean boundary to assess other potential effects of climate change.”
The biggest factors in determining future oxygen levels in Puget Sound are likely to be population growth, land use change and the relative success of strategies to reduce inputs of nitrogen from a variety of human sources, says the report.
“The change in flow regime, coupled with future land-cover-based concentrations, would alter the magnitude and timing of nutrient load delivery from watershed inflows,” the report says. “It is possible that future freshwater delivery could partly offset decreases in dissolved oxygen resulting from higher nitrogen loads. Additional investigation is warranted to understand these relationships.”
A decade ago, dozens of researchers investigated and reported on an unusual marine heat wave that brought warm waters from the ocean into Puget Sound beginning in 2014 and extending through 2016. The rare water condition nicknamed “the Blob,” produced temperatures up to 4 degrees F higher in some places in Puget Sound. The phenomenon was not good for most sea life, but it offered scientists a fascinating preview of what could happen more frequently in the future, as more heat waves have been reported across the globe.
The warm-water mass, created in the ocean during a period of intense sun and quiet weather conditions, grew large as it moved toward the coast. Scientists reported that plankton blooms started earlier and grew unusually large by the first summer. Plankton were not the typical assortment of species, which helped to distort the food web. Toxic plankton caused the closure of commercial and recreational shellfish beds.
Warm-water fish showed up in large numbers off the coast, and some came into Puget Sound. Anchovy populations seemed to flourish in South Sound. Jellyfish appeared in large numbers and scooped up forage fish, reducing the food supply for other species. Salmon altered their migration patterns. A large number of birds and some marine mammals were sickened or killed by toxic algae.
The warm water decreased oxygen levels in Puget Sound while increasing respiration rates among many species. In Southern Hood Canal, oxygen levels were practically zero in deep water. The Blob began to subside in 2016, and its effects diminished, but repercussions were long-lasting.
Many scientists, caught by surprise by the 2014-16 event, say they are prepared to measure environmental effects from beginning to end when the next big heat wave appears.
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This article was funded in part by King County in conjunction with a series of online workshops exploring Puget Sound water quality. Its content does not necessarily represent the views of King County or its employees.
The Series
Part 1: The debate over oxygen in Puget Sound
Part 2: Water-cleanup plans and the search for ‘reasonable’ actions
Part 3: Computer models spell out the extent of the water-quality problem.
Part 4: Many actions may be needed to improve Puget Sound waters