Cryptosporidium Monitoring Update

The Portland Water Bureau confirmed the detection of one Cryptosporidium oocyst in water samples collected from the Bull Run Watershed on October 20, 2025, as part of routine monitoring practices. This marks the first detection since October 12, 2025, and the Bureau has monitored for low levels of the microorganism since 2017. Currently, customers do not need to take additional precautions, although those with weakened immune systems should consult healthcare professionals regarding the safety of tap water. The Bureau, which does not treat for Cryptosporidium, is under a compliance schedule to install filtration by September 30, 2027. In the interim, the Bureau is executing watershed protection measures and enhancing monitoring efforts to protect public health.

Cryptosporidium can cause cryptosporidiosis, with symptoms ranging from diarrhea to severe illness in immunocompromised individuals. The Bureau collaborates with various water districts that also source water from Bull Run to ensure community safety. Public and media can access sampling results on the City’s website, and the Bureau will communicate any future risks promptly.