Fourteen people have come down with suspected cryptosporidiosis after visiting the indoor pool at McMenamins Anderson School in Bothell, with four of those cases diagnosed with cryptosporidiosis. Public health investigators have traced the illnesses to a narrow window late in August, when the sickened swimmers spent time in the hotel's North Shore Lagoon pool.
Public Health – Seattle & King County identified 14 suspected cases among people who visited the pool between August 29 and August 30, 2026; five symptomatic individuals were tested, and four were diagnosed with cryptosporidiosis, according to Kent Reporter. Investigators opened the inquiry after ill visitors reported swimming at the property in late August, the outlet reported. According to KIRO 7 News Seattle, King County Public Health says the outbreak is tied to an individual spending time inside the pool, and describes cryptosporidiosis as a highly contagious parasitic illness that can cause watery diarrhea.
A Well-Run Pool, But a Resilient Parasite
Notably, local health officials determined that the pool facility was well-maintained and fully compliant with county regulations, the Kent Reporter's report notes. The outbreak appears to stem not from any lapse in upkeep but from the nature of the parasite itself: Cryptosporidium oocysts carry a protective outer shell that lets them survive in properly chlorinated water for several days, per the same account.
That resilience is why eliminating the parasite from a contaminated pool typically requires more than routine chlorination. Federal protocols from the Centers for Disease Control and Prevention call for closing the facility and running a hyperchlorination procedure that reaches a concentration-time inactivation value of 15,300, a process that involves raising chlorine levels significantly while keeping bathers out of the water entirely.
Cryptosporidium is not a rare problem nationally. The Centers for Disease Control and Prevention estimates it causes roughly 823,000 cases of illness annually across the country and remains the leading cause of waterborne disease outbreaks linked to treated recreational facilities, though national surveillance suggests fewer than 2% of total annual cases are ever formally reported to public health agencies.
Symptoms Can Take More Than a Week to Appear
Cryptosporidiosis symptoms typically emerge within 2 to 10 days following exposure, and can bring watery diarrhea, stomach cramps, nausea, and dehydration lasting one to three weeks in otherwise healthy people. Most immunocompetent people recover without medical treatment, though the infection can turn severe or life-threatening for immunocompromised patients, according to the Centers for Disease Control and Prevention.
Because infected people can keep shedding microscopic parasites in their stool even after they start feeling better, Public Health – Seattle & King County advises anyone who experiences diarrhea to stay out of public swimming pools for at least two weeks after symptoms resolve. The county also recommends avoiding swimming in public pools while sick, not swallowing pool water, and rinsing off before entering the water, according to KIRO 7 News Seattle. Commercial pool operators in King County are required to report any facility-associated illness or outbreak to public health authorities within 48 hours of learning of it.
A Beloved Bothell Landmark
The North Shore Lagoon pool sits inside the Anderson School, a McMenamins property built in 1931 as Bothell Junior High and named after the school's first principal, Wilbert A. “Andy” Anderson. The building reopened on October 15 as a hotel, restaurant, and entertainment complex after Oregon-based McMenamins restored the art-deco campus into what has become a popular regional destination, per KIRO 7 News Seattle.
The pool itself is a draw in its own right: the 88-to-90-degree indoor saltwater lagoon is open to hotel guests and the general public alike, and it offers free admission to Bothell residents, according to ParentMap. The pool offers public swim sessions and water fitness classes.
It remains unclear whether additional cases tied to the late-August exposure weekend will surface as the investigation continues.
