King County declares end to cryptosporidiosis outbreak at McMenamins Bothell pool
King County Public Health confirmed that a cryptosporidiosis outbreak at the McMenamins North Shore Lagoon Swimming Pool in Bothell has ended. The investigation determined that 14 individuals were affected by the parasite, which is highly resistant to chlorine. Officials emphasized that the facility met all health and safety standards, but noted that the parasite can survive in well-maintained water for several days. Public Health advises swimmers to avoid using pools when ill and to rinse off before entering the water.
Key points
- King County Public Health (KCPH) officially closed the investigation into a cryptosporidiosis outbreak at the McMenamins North Shore Lagoon Swimming Pool in Bothell.
- The outbreak affected 14 people and was linked to an individual using the pool while infected with the parasite.
- KCPH stated that the McMenamins facility is well-maintained and complies with King County health and safety requirements.
- Cryptosporidium is highly resistant to chlorine and can survive in pool water for several days, even in well-maintained facilities.
- Symptoms of cryptosporidiosis include watery diarrhea, though many infected individuals may show no symptoms.
- KCPH recommends that people avoid swimming when sick, do not swallow pool water, and rinse off before entering the pool to prevent transmission.
Background
This incident follows a similar cryptosporidiosis investigation in San Diego County in September 2026, where four cases were linked to the Gaylord Pacific Resort pools. That earlier case highlighted the parasite's ability to survive in chlorinated water and its potential to cause watery diarrhea. While the San Diego case involved exposures between July and August, the Bothell outbreak was resolved by late September 2026. Other recent public health concerns in the region include a multi-state E. coli outbreak linked to raw cheese and a Salmonella investigation in Cache Valley, underscoring ongoing vigilance regarding food and waterborne pathogens.
Why it matters
The closure of this outbreak provides reassurance to the public regarding the safety of local recreational facilities, but it also serves as a reminder of the limitations of standard chlorine disinfection against certain parasites. The incident underscores the importance of individual hygiene practices, such as avoiding swimming when ill and rinsing before entering pools, to prevent the spread of resilient pathogens like Cryptosporidium. It highlights that even well-maintained facilities can be affected by biological factors that standard chemical treatments cannot fully eliminate.
What to watch
No further action is required from King County Public Health as the investigation is concluded. Residents are advised to continue following general pool safety guidelines, including avoiding swimming when experiencing gastrointestinal symptoms. McMenamins will likely resume normal operations at the Anderson School location, which is scheduled to open on October 15, 2026, following its transformation from the former Bothell Junior High School.
Want the full story? Read the original reporting
Read on KIRO 7 News Seattle