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Portland Water Bureau

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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.

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. As a result of Cryptosporidium detections in January 2017, the Portland Water Bureau was required to increase its monitoring to at least four days and a minimum of 250 liters per week to demonstrate whether the average Cryptosporidium concentration remains less than 0.075 oocysts per 1,000 liters over one year.  Additional detections of Cryptosporidium in February and March demonstrated that the concentration of oocysts would not be below this level after one year.

On May 19, 2017, the Portland Water Bureau was informed by OHA that the variance is being revoked. This was the result of the detections of Cryptosporidium in January through March of 2017. The number of oocysts detected show 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.

On August 1, 2017, OHA granted Portland a 60 day extension to the revocation of the variance to engage stakeholders “in the development of the City’s compliance proposal." On November 22, 2017, OHA, the Environmental Protection Agency, and the Portland Water Bureau agreed to an additional three-week extension to ensure full and thoughtful consideration of the compliance schedule and interim measures to implement once the variance is revoked.

The revocation of the variance will now be effective by December 13, 2017, or on the date OHA signs a compliance schedule and interim measures agreement with the Portland Water Bureau. The Portland Water Bureau submitted to OHA on October 9, 2017 the following:

  • A detailed proposed schedule of when the treatment will be in place.
  • Measures the Portland Water Bureau intends to take to reduce the risk of the public's exposure to Cryptosporidium until treatment is in place.
  • A proposed sampling schedule for Cryptosporidium at the intake until treatment is in place.

Until a compliance schedule and interim measures are agreed to, the Portland Water Bureau must sample, at the intake, at least 200 liters of water over at least 4 days per week and test for Cryptosporidium.  The Portland Water Bureau must continue to comply with all other conditions in the variance order until the date the revocation is effective. The remaining relevant conditions of the variance include the following:

Watershed Protection:

 Reporting and Notification:

Results from the Raw Water Monitoring are posted on the Cryptosporidium Monitoring Results page.

Monitoring results from the intake, Bull Run tributaries and wildlife scat are summarized quarterly in the list of current projects in the Bull Run Watershed Management Unit.

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.

Visit the Oregon Health Authority’s Bull Run Treatment Variance website for additional information.

Cryptosporidium Treatment Variance Monitoring Results

Cryptosporidium Monitoring Results

Watershed Inspection and Monitoring Plan

Treatment Variance Watershed Inspection and Monitoring Plan