Skip to Main Content View Text-Only

The City of Portland, Oregon

Portland Water Bureau

From forest to faucet, we deliver the best drinking water in the world.

Customer Service: 503-823-7770


More Contact Info

Treatment Variance for Cryptosporidium

Treatment Variance

On March 14, 2012, the Oregon Health Authority (OHA) issued the Portland Water Bureau a ten-year variance from the federal drinking water rules requiring the treatment of Bull Run drinking water for Cryptosporidium. As a result of the variance, the Portland Water Bureau does not currently treat for Cryptosporidium but is working to install filtration treatment by September 30, 2027.

OHA issued the treatment variance based on the Portland Water Bureau’s comprehensive LT2 Treatment Variance Request. The variance request was based on the results of a year-long water quality Sampling Plan and Study of Bull Run water and other supporting information.

More information on the basis for and requirements of the Water Bureau’s treatment variance are in the Final Order Issued by OHA Granting Portland's Treatment Variance.

As a condition of the variance, the Portland Water Bureau was required to conduct raw water monitoring for Cryptosporidium at least two days each week. On May 19, 2017, as a result of Cryptosporidium detections in January through March 2017, the Portland Water Bureau was informed by OHA that the variance is being revoked. The number of Cryptosporidium oocysts detected during this period showed that the Portland Water Bureau is no longer able to demonstrate an equivalent level of Cryptosporidium from untreated Bull Run water that would be expected with treatment.

The Portland Water Bureau is now required to meet the treatment requirements for Cryptosporidium  and is installing a filtration treatment plant by September 30, 2027 to meet these requirements.