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Portland Water Bureau

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GENERAL INFORMATION: 503-823-7404

1120 SW Fifth Ave, Suite 600, Portland, OR 97204

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Treatment Variance

Treatment Variance

On March 14, 2012 the Oregon Health Authority (OHA) issued the Portland Water Bureau a 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 treat for Cryptosporidium.

The treatment variance was issued in accordance with federal and state law and is valid for 10 years. The following are among the conditions contained in the variance:

Watershed Protection:

The Water Bureau must

Raw Water Monitoring:

  • The Water Bureau must conduct Observation Monitoring for Cryptosporidium at the Bull Run intake at least two days each week and each day when the turbidity is greater than 2.0 NTU.
  • If any one sample is positive for Cryptosporidium, the Water Bureau must begin Demonstration Monitoring. Under Demonstration Monitoring the Water Bureau must increase monitoring for Cryptosporidium to at least four days per week, with a minimum of 250 liters per week and at least 13,334 liters per year to demonstrate that the Cryptosporidium concentration is less than 0.075 oocysts per 1,000 liters.

Reporting and Notification:

The Water Bureau must:

  • Report the results of watershed and raw water monitoring to OHA. Any detections of Cryptosporidium must be reported to OHA within 24 hours. (Monthly Cryptosporidium Monitoring Reports to OHA)
  • Notify the public through posting on the website and press release of any detections of Cryptosporidium at the source water intake.
  • Notify OHA of any circumstances that may impact the conditions of the variance.

Cryptosporidium monitoring results from the intake, Bull Run tributaries and wildlife scat are summarized quarterly in item 31 of the list of current projects in the Bull Run Watershed Management Unit.

OHA may revoke the variance if the Water Bureau cannot meet the requirements of the variance, if EPA amends the LT2 rule in a manner that affects the provisions of the variance or if OHA deems that the lack of treatment for Cryptosporidium poses an unreasonable threat to public health. 

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.


Watershed Inspection and Monitoring Plan

Treatment Variance Watershed Inspection and Monitoring Plan

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