Birth of an Environmental Problem

Seattle- began discharging raw sewage into the wa­ters of Lake Washington at the beginning of the 20th century, as the city first began to expand east­ward from Puget Sound (Figure 2-2). By 1926 the lakeshore was sufficiently unpleasant that the city of Seattle passed a bund issue for a system of sewer lines to divert the city's sewage from Lake Washington to a treatment plant that discharged directly into Puget Sound. By 1941, the last sewer discharge into Lake Washington from Seattle proper had stopped, and the lake again became a pleasant place where people came to boat, swim, and fish.

Like many cities in the United States, Seattle is ringed by suburbs with individual municipal gov­ernments. These suburbs expanded rapidly in the 1940s, creating an enormous waste disposal prob­lem. Between 1940 and 1953, ten suburban sewage treatment plants began operating at points around the lake, with a combined daily discharge of 80 million liters (21 million gallons) into Lake Wash­ington. Each plant treated the raw sewage to break down the organic material within it and release the "harmless" effluent (that is, treated sewage) into the lake.

By the mid-1950s, although raw sewage dump­ing had ended, a great deal of treated sewage had been dumped into the lake. Try multiplying 80 mil­lion liters per day by 365 days per year by 5 to 10 years: enough effluent was dumped to give about 27 to 54 liters (7 to 14 gallons) of it to every man, woman, and child living on Earth.

The effects of this discharge on the lake were first noted by G. Comita and F. Anderson, doctoral students at the University of Washington in Seat­tle. Their studies of the lake's microscopic single-celled organisms in 1953 and 1954 indicated that

When Business to Environmentalists

The highly publicized 1991 decision by Mc­Donald's Corp. to abandon polystyrene "clamshell" burger boxes in favor of paper wrappers was reached in consultation with The Environmental Defense Fund (EDF), a Washington-based environmental group. This collaboration between a large American cor­poration and a group of ecological activists was an important breakthrough in coopera­tion. EDF continues to work with McDon­ald's, helping the company reach its ambi­tious goal to reduce its solid waste by 80%. In another collaborative first, the supermar­ket chain Safeway worked with the environ­mental group Earth Island Institute in 1991 to create a dolphin-safe policy regarding all filamentous cyanobacteria {what biologists used to call blue-green algae) were growing in the lake. These are long strings of photosynthetic bacterial cells strung together. Their appearance in Lake Washington was unexpected, because the growth of cyanobacteria requires a plentiful supply of nutri­ents, and deepwater lakes such as Lake Washington do net usually have enough dissolved nutrients to support cyanobacterial growth. Deepwater lakes are particularly poor in the essential nutrient phos­phorus. The presence of filamentous cyanobacteria in Lake Washington's waters hinted that the lake solved nutrients such as phosphorus (nutrient en­richment of lakes is discussed further in Chapter 21).

Sounding the Alarm

The first public alarm was sounded on July 11, 1955 in a technical report by the Washington Pol­lution Control Commission. Its author, citing tin work of Comita and Andersen, concluded that the treated sewage effluent that was being released into the lake's waters was raising the lake's levels of dis­solved nutrients to the point of serious pollution. Whereas primary treatment followed by chlorination of the sewage was ridding it of bacteria (see Chapter 21), it was not eliminating many chemi­cals, particularly phosphorus (a major component of detergents). In essence, the treated sewage was-fertilizing the lake by enriching it with dissolved

The process of nutrient enrichment of freshwa­ter lakes is well understood by ecologists, who call it eutrophication. Eutrophication is undesirable because, as Comita and Anderson had already begun to observe, high nutrient levels lead to the growth of filamentous cyanobacteria. These photo-synthetic organisms need only three things in order to grow: light for photosynthesis (which they get form carbon dioxide dissolved in water), and nutrients such as nitrogen and phosphorus (which were being provided by the treated sewage). Without the nutrients, cyanobacteria cannot grow: supply them, and soon mats of filamentous cyanobacteria form a green scum over the surface of the water, and the water begins to stink as dead cyanobacteria rot in the sun.

Then the serious problem begins: the bacteria that decompose the masses of dead cyanobacteria multiply explosively, consuming vast quantities of oxygen in the process, until the lake's waters be­come so depleted that they can no longer support other organisms that require oxygen to live. Fish can no longer extract enough oxygen through their gills, and neither can the myriad of tiny inverte­brates that populate freshwater lakes. For all intents and purposes, the eutrophic lake dies.

The local newspaper, the Seattle Times, men­tioned the Pollution Control Commission's techni­cal report in a July 11, 1955, article, "Lake's Play Use Periled by Pollution." The article did not grab the public's attention, but a month later, something else did: the annual Gold Cup yacht races, with their view of a magnificent sailboat's prow slicing cleanly through green scum and the not-so-subtle odor of rotting cyanobacteria. These addi­tions to what had been a popular summer holiday raised protest among spectators and lakeshore resi­dents.

Local authorities discounted the possibility that the cyanobacteria were the result of sewage into the lake, blaming them instead on the unusu­ally sunny weather. But on the very day of the yacht race, F. Anderson collected a water sample from the lake that was to forever banish such sunny

explanations. The sample contained a filamentous cyanobacteriurn that neither Anderson nor earlier investigators had ever encountered in the lake: Oscillatoria (Figure 2-4)- The presence of this cyanobacterium proved to be a vital clue. When Anderson's professor at the University of Washing­ton, W. T. Edmondson, reviewed the literature on eutrophication, he came across the name Oscillatoria again and again in the lists of organisms found in polluted lakes. In one review of the history of human-induced eutrophication in Europe and North America, he underlined Oscillatoria each time the word appeared in the text, and discovered that the organism was a nearly perfect indicator of eutrophication. The destruction of Luke Zurich in Switzerland decades earlier seemed a clear parallel with Lake Washington. Lake Zurich—also a large, Jeep lake—had been enriched by sewage effluent; cyanobacteria began to be noted; and, soon after (Oscillatoria appeared, water quality began to decline drastically.

To Edmondson, the appearance of Oscillatoria in Lake Washington was a clear warning. On Octo­ber 13, 1955, the University of Washington Daily ran a story, "Edmondson Announces Pollution May Ruin Lake," in which Edmondson announced the appearance of Oscillatoria and its likely mean­ing. From this point on, the scientific case was clear: the eutrophication of Lake Washington was reversed; it would soon destroy the water qual­ity of the lake.

Scientific Assessment

The purpose of the scientific assessment of an envi­ronmental problem is, first, to identify that a prob­lem exists and, second, to build a sound set of ob­servations from which to proceed in seeking a solution. Lake Washington's microscopic life had been the subject of long-term ecological studies by students at the University of Washington since 1933. Thus, when the telltale signs of pollution first appeared in 1952, they were quickly detected by Edmondson's students as changes from previous studies. Without the earlier students' careful analy­ses of the many forms of microscopic creatures liv­ing in the lake, understanding of the changes that were occurring would have been delayed.

Edmondson examined and compared the ear­lier studies of the lake and confirmed that there had indeed been a great increase in dissolved nutrients in the lake's water. Surmising that the added nutri­ents were the result of sewage treatment waste dis­charge into the lake by suburban communities, Edmondson formed the hypothesis that treated sewage was introducing so many nutrients into the lake that its waters were beginning to support the growth of photosynthetic cyanobacteria.

Edmondson's hypothesis made a clear predic­tion: the continued addition of phosphates and other nutrients to the lake would change its surface into a stinking mat of rotting cyanobacteria, unfit for swimming or drinking, and the beauty of the lake would be only a memory. Bolstering his predic­tion was the fact that lakes near other cities, such as Madison, Wisconsin, had deteriorated after re­ceiving sewage discharges.

The appearance of Oscillatoria in 1955 con­firmed Edmondson's prediction: pollution was pro­gressing in a classic pattern, its seriousness signaled by this almost-universal indicator of future trouble.

Making a Model By 1955 the ecology of the lake had been extensively studied, and a great deal was known about it. Edmondson used this data base to construct a hypothetical model of the lake, which traced the general quantitative relationships be­tween nutrient additions from sewage treatment plants and the growth of cyanobacteria in the lake's waters. By 1957 his model was sufficiently detailed to be used for quantitative predictions about the lake's future. It predicted a serious and rapid de­cline in water quality. Importantly, Edmondson's model also predicted that the decline could be reversed: if the pollution was stopped, the lake would clean itself at a predictable rate, reverting to its previous, unpolluted state within five years.'

Could anything be done to reverse the process? In April 1956, Edmondson outlined three steps that would be necessary in any serious attempt to save the lake: (1) comprehensive regional planning by the many suburbs that ringed the lake, (2) com­plete elimination of sewage discharge into the lake, and (3) research to identify the key nutrients that were causing the cyanobacteria to grow. His pro­posals received widespread publicity in the Seattle area, and the stage was set to bring scientists and civic leaders together.

Risk Analysis

It in one riling to suggest that the addition or" treated sewage to Lake Washington stop, and quite another to devise an acceptable alternative. Fur­ther, treatment of sewage can remove some nutri­ents, hut it is not practical to remove all of them. The alternative is to dump the sewage somewhere else—but where? In this case, officials chose to dis­charge the treated sewage into the Pacific Ocean. In their plan, a ring of sewers to he built around the lake would collect sewage treatment discharges, treat them further, and then transport them to be discharged at great depth into Puget Sound.

Why go to all the trouble and expense of treat­ing the discharges further, if you are just going to dump them? And why bother discharging them deep under water? Because it is important that the solution to one problem not create another. The plans to further treat the discharge and release it at great depth were formulated in an attempt to mini­mize the environmental impact of diverting Lake Washington's discharge into Puget Sound. It was assumed that sewage effluent would have less of an impact on the great quantity of water in the ocean than on the much smaller amount of water in Lake Washington.

Practically any course of action that can be taken to reverse an environmental problem has its own impacts on the environment, which must be assessed when evaluating potential solutions (see Focus On: Environmental Impact Statements). Environmental impact analyses often involve stud­ies by geographers, chemists, and engineers as well as geologists and other biologists. Furthermore the decision whether or not to implement a plan to restore or protect the environment is almost always affected by nonscientific factors and concerns. Any proposal is inevitably and rightly constrained by existing laws and by the citizens who will be af­fected by the decision.

Public Education

The scientific studies indicating the progressive pollution of Lake Washington first received public notice from the Washington Pollution Control Commission, which used the studies as the basis of its 1955 technical bulletin (already mentioned) convinced that urgent action was necessary. Public action required further education, and it was at this stage that scientists played a key role. Edmondson and other scientists wrote articles for the general public that contained concise explanations of what nutrient enrichment was and where it would lead. As these articles were picked up by the local news­papers, the general public's awareness of the prob­lem increased.

In December 1956, Edmondson, concerned about the delay of action, wrote a letter in an effort to alert the chairman of a committee (formed by the mayor of Seattle) on regional problems affect­ing Seattle and its suburbs. I le explained that even well-treated sewage would soon destroy the lake, and that Lake Washington was already showing signs of deterioration. Edmondson has received an encouraging response and prepared for the committee a nice-page report in, non technical language, of his scientific findings. After presenting his data show­ing that the mass of cyanobacteria varied in strict proportion to the amounts of nutrients being added m die lake, Edmondson posed a series of questions: "How has Lake Washington changed?" "What will happen if nothing is done to halt nutrient accumu­lation?" "Why not poison the cyanobacteria and then continue to discharge the effluent?" He then answered the questions, outlined two alternative courses of public action—do nothing or stop add­ing nutrients to the lake—and made a clear predic­tion about the consequences of each.

Political Action

Edmondson's report was widely circulated among local governments, but implementing its proposals presented serious political problems, because there was no governmental mechanism that would permit the many local suburbs to act together on re-

gional matters such as sewage disposal. In late 1957 the state legislature passed a bill permitting a public referendum in the Seattle area on the formation of a regional government with six functions: water supply, sewage disposal, garbage disposal, transpor­tation, parks, and planning. The referendum was defeated in March 1958, apparently because subur­ban voters felt that the plan was an attempt to tax them for the city's expenses.

Understanding the urgency of Edmondson's proposals, an advisory committee immediately sub­mitted to the voters a revised bill limited to sewage disposal. Over the summer there whs widespread discussion of the lake's future, and when the votes were counted on September 9, 1958, the revised bill had passed by a wide margin.

At the time it was passed, the Lake Washing­ton plan was the most ambitious and most expen­sive pollution control project in the United States. Every household in the area had to pay $2 a month in additional taxes for construction of a massive trunk sewer to ring the lake, collecting all the efflu­ent, treating it, and discharging it into Puget Sound, where the tides would carry it to sea.

The role of environmental science in address­ing problems such as the pollution of Lake Washington is limited to assessing the problem, evaluat­ing alternative solutions, and educating the public about these matters. Events then pass into the pub­lic arena, as they should. The proposed solution of Lake Washington’s problems involved considerable expense for every citizen in the area, as well as a radical reorganization of sewage treatment that transferred it from local to regional control. Recall that the first ballot proposal, to establish a regional district to deal with this and other problems, was defeated by voters because many other issues in addition to the pollution of Lake Washington af­fected the vote. Only by limiting the regional effort to sewage disposal and thus separating it from other concerns was the proposal eventually accepted by the voters.

The lesson is that the public is always con­cerned about many other matters in addition to environmental ones. Although the statement "The citizens of the Seattle area were presented with two clearly defined futures and were asked to choose between them" is true, it does not begin to take into account the many other factors, such as in­creased taxation and conflicting commercial and political interests, that influenced the public deci­sion.

Implementing the Plan of Action Ground-break­ing ceremonies for the new project were held in July 1961. As Edmondson had predicted, the lake had deteriorated further. Visibility in lake water declined from 4 meters (12.3ft) in 1950 to less than 1 meter (3.1 ft) in 1962, the water being clouded with cyanobacteria. On October 5, 1963, a suburban newspaper dubbed Lake Washington "Lake Stinko." In 1963 the first of the waste treat­ment plants around the lake began to divert its ef­fluent into the new trunk sewer; one by one, the others diverted theirs, until the last effluent was diverted in 1968. The lake's deterioration stopped by 1964, and then its condition began to improve Following Through By carefully analyzing what was happening in the lake, Edmondson could predict that the lake would recover fully. Not all environmental scientists agreed with him, many arguing that dissolved phos­phorus, the key nutrient regulating cyanobacterial growth, would not dissipate for decades, if ever. A lot depended on assumptions about the chemical makeup of the sediment at the bottom of the lake.

Edmondson was right. Water transparency re­turned to normal within a few years. Oscillatoria persisted until 1970, but eventually it too disappeared. By 1975 the lake was back to nor­mal. Indeed, by 1980 the lake was clearer than at any time in recent memory, with visibility exceed­ing 12 meters (39.4ft) at times. Before the recov­ery, the presence of filamentous cyanobacteria such as Oscillatoria had restrained growth of the lake's population of a microscopic organism called Daphnia (cyanobacterial filaments clog Daphnia's feeding apparatus). The disappearance of Oscillatoria and other filamentous cyanobacteria allowed the lake's Daphnia population to flourish and become dominant among the many invertebrate species that live there. Because Daphnia are very efficient eaters of nonfilamentous algae, levels of these algae in the water fell, too, so that the water became even clearer. A dozen years later, in 1992, the lake re­mains clear.

Every environmental intervention is an experi­ment, the diversion of sewage discharge from Lake Washington was nothing more or less than a large-scale experiment in nutrient cycling in a freshwater lake, and Edmondson's model made clear predictions about the results of the ex­periment. By carefully monitoring the outcome of the sewage diversion, Edmondson was able to con­firm that it matched his model's predictions.

Monitoring is necessary because environmental scientists work with imperfect tools. There is a great deal we don't know, and every added bit of information increases our ability to deal with future problems. The knowledge that Edmondson's ap­proach to modeling the Lake Washington situation worked provides helpful information to today's environmental scientists. They would not have this information if the lake's recovery had not been monitored. Knowledge about the effects of envi­ronmental interventions is almost always valuable.

It is a mistake, however, to assume that we al­ways know just what is going to happen. Edmondson's model did not predict, for example, that the lake would become even clearer before, be­cause the role of Daphnia in keeping down the lev­els of nonfilamentous algae was not anticipated. The unanticipated always lurks just beneath the surface of any experiment carried out in nature, because our knowledge is limited. There is much to be learned from careful observation of the results of environmental "experiments."