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Lake Washington: Fighting Pollution and Winning

Lake Washinton polluted since the 50's Lake Washinton polluted since the 50's
11 Jun

Lake Washington: Fighting Pollution and Winning

If there's one lesson we can learn from the past century of the pollution and cleanup of Lake Washington, it's that there's no such thing as a city lake that doesn't get dirty. The real concern for Lake Washington and bodies of water like it isn't whether or not a city pollutes the water in its borders, but whether or not the city is effective in cleaning that water.


Lake Washington exists entirely within the densely populated land of the Seattle/Eastside area. Its west shore touches the fringes of Seattle's city core and its eastern shore serves as the private docking space of the wealthy area consisting of developed suburbs such as Bellevue, Kirkland and Kenmore. It's also where the populated Mercer Island rests.

The Seattle/Eastside area has only been urbanized for around a century, but the industrial nature of Seattle's early decades didn't treat Lake Washington kindly. Though the lake today is rated as “swimming” water, meaning it's considered safe to enter for people, it wasn't always so. The combination of industrial runoff and standard household waste like treated sewage and detergent rendered Lake Washington a murky, inhospitable mess as of the early 1950s.

The full extent of Lake Washington's pollution came about through research conducted by zoologist W. Thomas Edmondson and his students at the University of Washington. Edmondson, who died in 2000, was an expert in invertebrate life, like algae and plankton. His studies into the lifeforms of Lake Washington yielded startling data about the increase in blue-green algae in the water. The algae flourished in the polluted environment but died off quickly, washing up on Seattle's beaches and creating an incredible stench that led the Seattle Post-Intellgencer to dub it “Lake Stinko” in the 1960s.

Though dumping a city's sewage into any body of water is a level of pollution that body isn't naturally equipped to handle, dumping it into an enclosed lake is especially problematic. Lakes don't experience much flow or tidal forces, meaning that whatever goes into them has a tendency to stay there. This is what happened to Lake Washington and the effect was enough to influence the evolution of a particular fish that made its home there.

The Threespine Stickleback is a small fish that came to Lake Washington long ago from harsher, larger bodies of water. It's an ancient fish that was kicking around in marine environments for tens of thousands of years, adapting to life in Lake Washington when it first appeared upon the recession of the glacier that covered a significant chunk of what is today the United States. In those pre-industrial days, the Stickleback enjoyed clear, clean waters, but also needed to develop plated scales and a more robust body to survive attacks from predators.

Then the pollution of the 1900s hit Lake Washington and the Stickleback benefited more from a smaller, less demanding body and a greater ability to hide in the murky deep. The entire species shrank, lost much of its plating and even saw a reduction in the rigidity of its sharp spines by the mid-1950s. After the cleanup effort went into full swing by the late 1960s and early 1970s, the Stickleback found itself in clearer water again and the marine population from which it descended took over, mixing its heartier DNA back into the gene pool and essentially reviving the fish as it appeared 200 years ago.

Dr. Edmondson and his fellow biologists were responsible for the plan to save Lake Washington from its dramatic pollution, recommending that the sewage treatment plants in Seattle divert their water to a deep pipeline in Puget Sound where the larger body of water could dilute the sewage and take advantage of its tidal flow to carry the waste away.

It wasn't a quick or easy process, though. It was politics, rather than science or industry, that delayed the reclamation of Lake Washington. The lake's condition was dependent on the formation of a stronger city government in Seattle, the Metro program that streamlined resource management and city planning. Many King County voters weren't keen on the idea of a metropolitan government in Seattle through most of the 1950s, but a narrow win for the Metro-creating ballot measure in 1958 finally sealed the deal and made it possible to coordinate all of Seattle's sewage treatment facilities.

By the 1970s, Lake Washington achieved a healthy level of clarity as pollutant and algae levels declined. By the 1990s, the clarity and cleanliness of the lake was as good as it had been prior to industrialization. Today, the city of Seattle tests the water at several Lake Washington beaches weekly during the warmer half of the year, publishing monitoring data online and controlling contaminating sources like broken sewage lines and geese populations. It's rare for any given beach on Lake Washington to veer into even moderately unhealthy levels of pollutants.

The same can't be said for Puget Sound. As the development around it grows and the fishing practices in the sound destabilize animal populations, the condition of the water declines more each year. The solutions of 1958 for cleaning up Lake Washington have essentially resulted in the problem of how to clean up Puget Sound in 2012.