In March 2012, the Oregon Health Authority (OHA) issued the Portland Water Bureau a variance from the state an federal drinking water rules requiring the treatment of raw water from the Bull Run Watershed for the parasite Cryptosporidium. A variance is state permission not to meet a maximum contaminant level (MCL) or a treatment technique under certain conditions. OHA issued the Portland Water Bureau the treatment variance for Cryptosporidium based on substantial data and analyses presented in the LT2 Treatment Variance Request for the Bull Run drinking water source. Among the conditions of the variance was monitoring at the Bull Run raw water intake to demonstrate a level of Cryptosporidium that was equal or better than what would be expected with treatment.
After years of not detecting any Cryptosporidium at the Bull Run intake, it was detected above this level in 2017 from January through March and September through December. As a result of the January through March detections, OHA revoked the Bull Run Treatment Variance on Dec. 18, 2017.
The revocation of the variance prompted the City to consider options for meeting treatment regulations. On Aug. 2, 2017, the Portland City Council voted unanimously on a resolution to move toward building a water filtration plant to treat Bull Run water.