Here’s why recent flooding sent millions of gallons of sewage into Bellingham Bay
Recent storms sent nearly 30 million gallons of raw sewage into Bellingham Bay over the past three weeks, according to the city of Bellingham.
The sewage overflow events — one for about 30 hours Nov. 14-15 and another for 7.5 hours Nov. 28-29 — alarmed some local environmentalists, who are concerned about the impact on water quality and wildlife health. Raw sewage contains anything you can imagine pouring down a sink or flushing down a toilet, including fecal bacteria, chemical contaminants and excess nutrients.
Bellingham’s sewer and stormwater systems are connected, the result of an antiquated infrastructure decision from the early 1900s, according to Shawn McKone, an environmental engineer with the state’s Department of Ecology. Many older cities in Washington have similar setups, including Anacortes and Everett.
On a typical day, all of Bellingham’s wastewater is routed to the Post Point Wastewater Treatment Plant. But when the plant is running at its full capacity of 75 million gallons a day, some sewage may need to be discharged into the bay, said Eric Johnston, Bellingham’s public works director. The alternative is risking it backing up into people’s homes.
“Sometimes we just cannot keep up with Mother Nature’s glory,” Johnston said.
Combine the sewage with the other pollutants that the intense rains washed into local waterways, and you have potentially deadly results for the organisms that need clean water to thrive, said Kirsten McDade, pollution prevention specialist at local environmental nonprofit RE Sources.
“I’ve been referring to these rain events as a toxic tidal wave,” she said in an email to The Bellingham Herald.
But city officials said in a Nov. 28 news release that the water quality impacts of the sewage overflow are expected to be minimal.
“I was surprised at the laissez-faire tone of the City’s blog,” McDade said.
Cumulative repercussions
Assessing the impact of these “acute toxicity events” is difficult, she acknowledged, unless dead fish start to show up in the water or someone is actively monitoring the water quality. But over time, the cumulative environmental repercussions will become clear, she said.
“It is only much later do we realize the consequences,” McDade said. “It’s kind of like heart disease — it slowly creeps up on you after years of unhealthy behaviors.”
It’s not that city officials don’t care about sewage going into the bay, said Bellingham Public Works Director Johnston. But he stressed that sewage is typically mostly water and that the pollution discharged last month was even further diluted by the massive amounts of water flowing into the bay from local streams.
During the sewage overflow in mid-November, Whatcom Creek discharged 650 million gallons of water into the bay, compared to the 26.5 million gallons of raw sewage overflow. During the overflow event in late November, Whatcom Creek discharged 206 million gallons of water into the bay, compared to 2.75 million gallons of sewage overflow.
Dilution helps
“The solution to pollution is not dilution,” Johnston said. “But the reality of the situation is that that’s the case.”
Although they may dilute pollution, these high flows are not completely innocuous even on their own, said McDade, the pollution prevention specialist at RE Sources. They can churn up sediment that suffocates fish and interferes with their ability to navigate.
Washington state allows Bellingham to discharge sewage into the bay, as long as it only happens once a year on average. Currently, the city is well within those limits, with its last overflow event before November happening in 2009, during a similarly intense storm, Johnston said.
But as human-caused climate change brings more intense, frequent storms to the region, Department of Ecology officials are warily keeping tabs on a potential increase in sewage overflow events. Washington cities can no longer rely solely on historical overflow data when planning sewer and stormwater system capacity, said McKone.
“Trying to rely on past data is going to give a false sense of security,” he said. “But how to project out what the right number will be to use in the future is almost an impossibility.”
“Preparing for bigger is about as far as we can go right now,” added Steve Hood, also an environmental engineer at the Department of Ecology.
Separating stormwater, sewer
McDade said that Bellingham needed to “fully separate our stormwater and sewer, like yesterday.” That is the goal, Johnston said, but there is no timeline for when separation will be completed. As the city undertakes sewer rehabilitation projects, it is slowly separating stormwater and sewer pipes. Work has also been done to reduce the amount of stormwater going into the system, which includes creating rain gardens that can help some precipitation soak into the ground.
Bellingham is taking a “gold standard approach” to reducing its sewage overflow events, particularly compared to cities like Seattle and Everett, said McKone with the Department of Ecology.
McDade, the pollution prevention specialist, hopes to see a day where Bellingham can eliminate sewage from going into the bay altogether.
“Ideally, we want to see no overflow events,” she said. “We want to see all sewage going to the treatment plant.”
