Before early settlers built the region’s first sawmill at Tumwater in 1848, before Arthur Denny and his party settled the future city of Seattle in 1851, and before the federal government created Washington Territory in 1853, the waters of Puget Sound and its freshwater streams were as clean as nature could provide. Fish and wildlife were abundant, having adapted to local conditions alongside native people of the area. 

Needless to say, things have changed since those days. In the parlance of today’s water-quality regulations, the clean waters of yesteryear are known as “natural conditions.” Nobody believes that we will ever see those conditions again, but the term “natural conditions” has taken on a profound meaning as a point of reference. How far do we humans want to go in restoring polluted waters and limiting unhealthy discharges of wastewater into Puget Sound?

Washington Department of Ecology is currently struggling to establish a regulatory system involving natural conditions, based on the idea that it makes no sense to set cleanup goals beyond the best that nature has ever provided. The federal Environmental Protection Agency, which maintains ultimate authority over the nation’s waterways, overturned Ecology’s existing natural conditions rule in 2021. Since then, Ecology has been working on a revision, particularly addressing water-quality goals for temperature and dissolved oxygen. 

The agency recently completed limited rules for setting cleanup standards in defined locations. The ongoing effort is to create an enduring “performance-based” program that would empower experts to identify natural conditions anywhere in Puget Sound, along with an approved allowance for human degradation. The first draft received rather harsh comments from the EPA. A revised proposal that addresses only dissolved oxygen for marine waters was released for public comment this week.

In a letter to Ecology about the first draft, Rebecca Garnett, manager of standards and assessment for EPA’s Region 10, said any new water quality criteria must meet scientific standards, be spelled out in sufficient detail, and fully protect aquatic creatures. “As currently proposed,” she wrote, “the EPA is concerned that Ecology’s performance-based approach for developing site-specific natural conditions criteria is not sufficiently ‘binding, clear, predictable, and transparent.’” 

In a legal sense, water quality standards are essential, because they determine how much money is spent by government and industry to clean up our troubled waterways and improve survival for fish, crabs and other animals. According to some estimates, billions of dollars may be needed to bring major sewage-treatment plants into compliance.

Documentation used to justify dissolved oxygen standards, developed more than 50 years ago, appear to be lost, according to Ecology’s Water Quality Program, but agency officials maintain that available studies still support those numeric limits as protective of aquatic creatures.

Developing these new water-quality standards is complicated and intriguing, involving computer models to describe water-quality conditions that existed long before people changed the environment. A typical method of estimating natural conditions is to go out and measure current conditions in specific areas and then subtract all known causes of human degradation, often with the help of computers.

Natural conditions criteria may come into play when a body of water fails to meet established “numeric criteria.” Numeric criteria are levels of oxygen and temperature that scientists say will meet the biological needs of aquatic creatures. Exceptions to numeric criteria are allowed for areas that have naturally lower levels of oxygen or naturally higher temperatures than the numeric criteria. For oxygen, the numeric criteria for most of Puget Sound is no less than 6 or 7 milligrams per liter, depending on the location. Based on studies, it appears that most of Puget Sound has never met those standards — not even in prehistoric times. This means that we could eliminate all human causes of low oxygen and still come up short of the approved numeric criteria.

This dilemma raises the stakes for choosing the correct natural conditions criteria. It also raises questions about whether Puget Sound is using the correct numeric standards, originally developed in 1967. Some officials in local government and industry as well as some scientists are calling for Ecology to overhaul the numeric criteria for oxygen throughout Puget Sound. The nonprofit advocacy group Association of Washington Cities, among others, would like the Legislature to fund a study to determine the actual needs of aquatic creatures in Puget Sound. For now, Ecology has placed a higher priority on developing natural conditions criteria.

“This matters,” states a news release from the agency, “because Ecology and all organizations working on clean water efforts need to focus the state’s pollution-reduction efforts on waterbodies where humans are causing pollution, not on waterbodies that are naturally different.”

Fitting nature into a regulatory framework

Arguments over how far to go in cleaning up the streams, bays and open waterways of Puget Sound have their regulatory foundation within the federal Clean Water Act of 1972.  The law establishes a national policy to “restore and maintain the chemical, physical and biological integrity of the nation’s waters.” The law asserts a goal of eliminating all water pollution and directs the Environmental Protection Agency to follow a specific process, in concert with the various states.

The Department of Ecology, authorized by the EPA to administer the Clean Water Act in Washington state, has its hands full in issuing permits for pollutant discharges, developing cleanup plans for polluted waterways, enforcing regulations to protect marine and fresh waters, and safeguarding the health of humans and animals. 

Water quality standards have been developed and formally approved to protect aquatic species, human health, human activities and even esthetics, such as odor and appearance. For aquatic species, the numeric limits for physical and chemical conditions are based on the goal of protecting the most sensitive species in designated areas.

Oxygen is considered an essential element for sea life in marine waters. Numeric criteria for oxygen in Puget Sound, ranging from 4 to 7 milligrams per liter, date back to 1967 under the Federal Water Pollution Control Act, the predecessor to the Clean Water Act. Documentation used to justify those standards, developed more than 50 years ago, appear to be lost, according to Ecology’s Water Quality Program, but agency officials maintain that available studies still support those numeric limits as protective of aquatic creatures.

Most of Puget Sound is designated for a minimum of 7 mg/l. Areas to the west of Whidbey Island and into Bellingham Bay are designated for no less than 6 mg/l. The innermost portions of Tacoma’s Commencement Bay, Olympia’s Budd Inlet and Shelton’s Oakland Bay are designated for 5 mg/l, down to 4 mg/l in a few relatively tiny areas of those waterways.

Critics argue that 6 or 7 mg/l is generally overly protective of water quality, since most areas of Puget Sound apparently never met those standards, not even in prehistoric times when marine species were abundant. Some say the criteria should be updated with more recent science, perhaps considering the depth of channels and other factors that affect natural oxygen levels. Chesapeake Bay on the East Coast has taken this approach. As things stand, the numeric criteria for Puget Sound are destined to be largely displaced by natural conditions criteria based on computer models. 

Biological needs of species

The concept of using a numeric standard for water quality is rather simple, perhaps too simple, some people say. For example, one can estimate, based on laboratory studies, the biological needs of salmon, including healthy levels of temperature and oxygen. These biological requirements may vary, depending on the activity of the fish, its body condition and other factors.

The biological needs may be complex and dynamic, yet Washington’s numeric water quality criteria are reduced to single numbers. Much of Puget Sound has been designated as “extraordinary” water quality, a category that calls for a minimum oxygen level of 7 mg/l and a maximum temperature of 13 degrees C (55.4 F). Other criteria establish limits for turbidity, acidity and bacteria.  Besides “extraordinary,” various areas of Puget Sound have been designated as “excellent,” “good” or “fair,” each with their own criteria to protect named species residing there.

Oxygen and temperatures can vary by location and depth in Puget Sound. State regulations call for taking measurements at depths that represent the “dominant aquatic habitat” at each monitoring site. Such monitoring helps to determine whether a water body complies with established criteria or is “impaired” for certain water quality parameters. Because conditions change over time, particularly with seasonal cycles, some areas may comply at one time but not another.

Since few areas of Puget Sound can meet the numeric criteria for dissolved oxygen at all times, even under natural conditions, some individuals and groups are calling for revisions to the criteria. They contend that limits of 6 or 7 mg/l are considerably higher than needed to protect marine life in Puget Sound. Rather than resorting to computer models to determine natural conditions criteria, scientific studies could help establish new numeric criteria based on biological needs. 

“Ecology has acknowledged that it has no documentation as to the scientific basis for the marine DO standards that were adopted by a predecessor agency in 1967,” said Carl Schroeder of the Association of Washington Cities, commenting on the proposed natural conditions criteria.

Schroeder noted that cities are responsible for many of the sewage-treatment plants in Puget Sound, including those facing costly upgrades to improve oxygen conditions. Since costs must be passed on to customers via higher sewer rates, local governments must be able to explain the rationale for Ecology’s water quality standards, he said.

After 56 years without a clear scientific foundation, he continued, “it is startling that Ecology continues to move forward without seeking or incorporating information on the dissolved oxygen needs of the organisms present in Puget Sound.”

During last year’s legislative session, Schroeder and others attempted to get Washington lawmakers to appropriate $500,000 for a scientific review of the biological needs of Puget Sound species in connection with the state’s cleanup standards. The proposed study would have involved the Washington Academy of Sciences. Funding for the study was approved by the House but failed to survive final negotiations in the Senate. This year, Schroeder continues to push for legislative funding, despite tight budget conditions. 

Lincoln Loehr, a retired oceanographer and environmental consultant, has been on a crusade of sorts to get Ecology to review the numeric criteria for oxygen. He first petitioned the agency to review the oxygen criteria in 1998, before most people were aware that natural conditions criteria would become such a key factor in setting cleanup targets. Loehr shared his views with many technical groups working on the low-oxygen problems of Puget Sound, and in 2017 he petitioned Ecology again to review the numeric criteria.

“Washington’s marine DO water quality criteria, adopted in 1967, have no discoverable scientific basis,” Loehr wrote in a report reviewing the history of numeric criteria and recommending that the EPA step in and develop new criteria. “While the state can identify waters as not meeting these criteria, that determination does not demonstrate that the waters are impaired, as the comparison is made with baseless criteria.  Similarly, computer modeling to compare to a 0.2 mg/l decrease in DO from human causes (part of the state's criteria) is not a basis for demonstrating impairment, as it has no biological basis.”

Responses from EPA officials have offered no support for revising the state’s numeric criteria, which federal law says can be more restrictive than federal requirements. Ecology officials defend the existing criteria as being protective of marine species, but critics contend they are overly protective. Loehr argues in favor of changes to the numeric criteria, saying the Clean Water Act calls for standards that accurately reflect the “latest scientific knowledge.”

Sara Thitipraserth, director of natural resources for the Stillaguamish Tribe, expressed similar concerns in letters to Ecology and the EPA.

“It is the view of the Stillaguamish Tribe that the Marine Dissolved Oxygen Water Quality Criteria of Washington state are in need of thoughtful, science-based revision,” she wrote. “They are outdated, simplistic, and fail to consider the geography and hydrology of Puget Sound. Neither are they based on or referenced with scientific research…

“Once appropriate standards are established,” she added, “it is likely that many so-called water quality exceedances will cease to exist. Currently, marine waters with 5 mg/l dissolved oxygen in many deep-water basins are considered noncompliant, when in fact the oxygen level poses no threat to organisms that might be using it. Scientists in the region commonly acknowledge that the harm to a deep-water marine biological community does not occur until the water becomes hypoxic, that is, when oxygen levels drop below 2 mg/l.”

Measuring the needs for oxygen

Tim Essington, a fisheries ecologist at the University of Washington, has studied the effects of oxygen depletion on many species in Puget Sound. Although not directly involved in regulatory issues, Essington’s research involves studying biological thresholds. For example, declining oxygen levels eventually reach a point when fish must respond with physiological or behavioral changes if they are to survive. This level of oxygen is called the “critical threshold” for a given species, and it varies by temperature.

A key issue is whether the laboratory environment accurately represents conditions faced by aquatic animals in the real world. Fish in a lab, for example, are held under precise conditions of oxygen and temperature to see how they respond, whereas fish in the wild are likely to swim away and seek better conditions when faced with low oxygen levels. Activity and stress can affect their metabolism and their need for oxygen. Temperature is another factor.

“In the lab, you are measuring routine behavior; the fish is not trying to chase down food,” Essington said. “But in terms of ecological relevance, animals do need to eat. The process of finding food costs oxygen, and there is also the need to avoid predators.”

Animals can acclimate to low-oxygen conditions, such as what occurs when a human athlete trains at high altitude, he continued. The oxygen capacity of the blood can change, and fish can even increase the surface area of their gills. Meanwhile, over generations, localized populations within a species may adapt to low-oxygen conditions and pass on those traits to their offspring.

Studying the presence or absence of species under various oxygen conditions can provide clues to their needs in the wild, Essington said, but one needs to understand that the most sensitive species may already be gone. Such observations of wild behavior can be compared to observations in a lab to better understand the oxygen needs of Puget Sound species.

In Chesapeake Bay on the East Coast, the EPA faced the challenge of low-oxygen conditions by dividing the bay into five habitat types, including considerations for the depth of the water. Since deeper water typically contains less oxygen, dominant species are more tolerant of those conditions. The resulting guidelines (PDF) were completed in 2003 with numeric criteria for oxygen, water clarity and chlorophyll. They were subsequently adopted into regulations by the four governmental jurisdictions around the bay: Washington, D.C. and the states of Maryland, Virginia and Delaware.

Proponents of changing Washington state’s numeric criteria for oxygen often point to Chesapeake Bay as an example of how to fit biological needs into a regulatory framework.

EPA identified and described five habitats to ensure the protection of the living resources of the Chesapeake Bay and its tidal tributaries. Some say a similar approach would be appropriate for Puget Sound.

An alternative approach 

In establishing numeric criteria for Chesapeake Bay, the Environmental Protection Agency divided the bay into five habitat types to protect species in each location. Each has its own standards for dissolved oxygen:

Migratory fish spawning and nursery. Largely freshwater streams and tidally influenced locations where freshwater comes into saltwater. Oxygen levels must generally be above a seven-day average of 6 mg/l from Feb. 1 to May 31, when young fish are migrating. Levels are allowed to drop to 5.0 or 5.5 mg/l, depending on salinity, from June 1 to Jan. 31.

Shallow water bay grass. Mostly underwater areas near the shore where fish and crab find food and protection from predators among the vegetation. Oxygen criteria call for a 30-day average no lower than 5.0 or 5.5 mg/l, depending on salinity, although a seven-day average of at least 4 mg/l also meets the standard.

Open-water fish and shellfish. Includes surface waters in streams, embayments and open waters of the bay where diverse populations of fish spend their time. Oxygen criteria call for a 30-day average no lower than 5.0 or 5.5 mg/l, depending on salinity, although a seven-day average of at least 4 mg/l also meets the standard.

Deep-water seasonal fish and shellfish. Representing transitional waters between the well-mixed surface waters and the deep channels of the bay where bottom-feeding fish, crabs, oysters and other species live. Numeric criteria call a 30-day average oxygen concentration of at least 3 mg/l or a one-day average of 2.3 mg/l, except for Oct. 1 to May 31 when the higher “open-water” criteria apply.

Deep-channel seasonal refuge. The home of sediment-dwelling worms and small clams consumed by bottom-feeding fish and crabs, a habitat known for very-low oxygen levels. To meet the criteria, oxygen levels must never get below 1 mg/l.

Note: These five habitats also include absolute minimums, separate from averages, which must never be exceeded. For some species, temperature is also considered. 

Natural conditions approach

From the beginning, Ecology officials realized that some areas of Puget Sound contained naturally low levels of oxygen that could never meet the numeric criteria, even under the best conditions. 

“We have long acknowledged that (portions of) Puget Sound is naturally impaired for DO,” said Leanne Weiss, unit supervisor in Ecology’s Water Quality Management Division, “and that’s why these other processes and options are so important.”

In fact, when considering all the nation’s waterways, EPA recognized as early as 1997 that natural conditions, absent human impacts, might be lower in oxygen or higher in temperature than numeric criteria in some areas. A 1997 memo (PDF) establishes a policy allowing for numeric limits to be supplanted by natural levels.

Current revisions to Ecology’s natural conditions regulations came about from a lawsuit filed by Northwest Environmental Advocates. In response to the lawsuit, the EPA agreed to reconsider its 2008 approval of Ecology’s natural conditions rule. After review, the EPA reversed its approval (PDF), leaving Washington without a natural-conditions option for cleanup goals.

One reason for the reversal was the lack of a clear statement that the natural conditions criteria applied only to aquatic life, not to human health standards, according to the EPA. As described in the 1997 EPA memo on natural conditions criteria, aquatic species may adapt over time to waters with naturally low levels of oxygen or high temperature, but that’s not the case for humans. People should be protected from harmful natural conditions by changing the “designated use” of a waterway, the memo says. That might mean excluding fishing or other recreational activities or even issuing public-health warnings.

Ecology’s revised rule is written to limit its application to aquatic species. 

“Having a standard to determine what is normal and natural for a particular waterbody is important information for setting discharge limits and knowing when action is needed to protect or restore water quality,” Ecology states on its rule-making webpage. “Nearly every state and many tribal nations have a provision in their EPA-approved water quality standards to protect aquatic life based on natural conditions of the water bodies.”

EPA specifically overturned Ecology’s natural conditions criteria for both oxygen and temperature in marine waters and freshwater streams. It did not overturn the criteria in lakes, which EPA determined to be adequately protective as written into the rule.

Oxygen is often the driving factor for marine creatures, and it has received much attention from Ecology because low-oxygen conditions are creating serious problems in Puget Sound. While oxygen levels are a concern in some streams, temperature can be a critical factor for fish where logging has removed large trees that help keep the waters cool (Encyclopedia of Puget Sound). 

As with oxygen, when studies show that natural conditions are warmer than designated temperatures, streams have been allowed to reach their estimated “natural” temperatures plus 0.3 degrees — the “human use allowance.” 

EPA did not determine whether the human use allowance of 0.2 mg/l for oxygen and 0.3 degrees C for temperature was or was not close enough to the actual levels expected under natural conditions, but the agency did insist that Ecology provide scientific justification for those allowances. EPA’s 1997 memo allowing for natural conditions does not mention any such allowance. 

To get natural conditions back into play, Ecology has been working on a performance-based approach — a step-by-step process approved through a formal rule-making procedure. Public comments on the new proposal are being accepted until May 22. Once the process is adopted by Ecology and approved by the EPA, anyone could theoretically follow the process. Ecology would be responsible for establishing allowable limits for temperature or oxygen anywhere in Puget Sound. The resulting natural conditions criteria, based on careful modeling, would be accepted by authorities without further approval. 

The first draft maintained 0.2 mg/l and 0.3 degrees C as allowable deviations, consistent with rules adopted years ago and renewed in November. Without these allowances, cleanup standards for oxygen and temperature would need to be set at the natural levels seen in prehistoric times, officials say. Such levels would be unattainable in today’s world of human impacts. 

Ecology has approved one change to tighten the human use allowance. When natural oxygen conditions are found to be very low — specifically below 2 mg/l — the human use allowance is limited to 10 percent below the natural level. For example, if the natural oxygen level is 1 mg/l, then the allowance can be no more than 0.1 mg/l, setting the cleanup target at 0.9 mg/l. 

Endangered species protections

During the 2008 approval of the natural conditions criteria, federal agencies responsible for protecting listed species under the Endangered Species Act analyzed the effects of Ecology’s revised water quality standards for oxygen and temperature, including the relevant human use allowances: 0.2 mg/l for oxygen and 0.3 degrees C for temperature. While the standards may not fully protect listed salmon during all life stages, they are “not likely to jeopardize the continued existence” of the listed species, according to the National Marine Fisheries Service. When the current revisions are complete, the federal agencies are expected to undertake a new analysis of the natural conditions rule, taking into account changing conditions and new research. They must show that the new rule is protective of threatened and endangered species before it can become effective.

Because the performance-based approach relies on computer modeling to identify natural conditions, the process outlined by Ecology prescribes model selection, assumptions, operation and reliability; choice of data; considerations of climate change; interpretation of model outcomes; documentation; peer review; and many other issues. Ecology’s proposed revisions have been drafted with guidance from EPA’s natural conditions “framework” (PDF).

When the first version of the performance-based approach was released for public comment last May, the document was met with many questions and concerns. Among other things, the EPA called for adding “critical steps” in the process; stronger language to convey that each step is “binding” on the applicant, not voluntary; plus additional detail to “ensure a repeatable and transparent process.” 

One of the challenges in determining natural conditions is to identify ALL the human sources affecting the waterway. If any human sources are missed, the resulting estimate of natural conditions could lead to cleanup standards that adversely affect species that are still present and preclude the return of missing species.

While an approved performance-based approach would allow Ecology to establish water quality goals without further rulemaking, another approach is to study a particular area and propose water quality criteria that meets the needs of species in that area. Results from this “site-specific approach” would be proposed and adopted as a rule by Ecology with final approval from the EPA.

In the end, whether cleanup goals are based on numeric criteria or on natural conditions, the ultimate goal is to restore water quality for all species in Puget Sound — including, as much as  possible, those species that thrived when natural conditions prevailed.

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.