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Portland Water Bureau

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


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

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Uncovered Reservoirs

Washington Park Reservoir 4

Portland has a schedule to replace its open finished drinking water reservoirs with enclosed storage by December 31, 2020.

A finished drinking water reservoir contains water that has been through all the treatment steps required by the federal Safe Drinking Water Act and can be delivered to the public without further treatment. Five of Portland’s finished drinking water reservoirs are uncovered. Three are located at Mount Tabor Park and two are located in Washington Park.

The Long Term 2 Enhanced Surface Water Treatment Rule (LT2) affects uncovered finished drinking water reservoirs by requiring that water systems either cover the reservoirs or provide treatment at the outlets of the reservoirs to remove or inactivate 99% (2 log) of the Cryptosporidium protozoa, 99.9% (3 log) Giardia bacteria and 99.99% (4 log) of viruses.

Following a federal court's rejection of its legal challenge to the final LT2 rule, Portland developed a schedule for replacing its existing open drinking water facilities with enclosed storage. Portland was required to submit the schedule and have it approved by the federal Environmental Protection Agency (EPA) by April 1, 2009. EPA approved the schedule on March 27, 2009.

In November 2009, then Commissioner-in-Charge Randy Leonard, requested direction from the EPA regarding how the City could pursue a potential variance to the uncovered reservoir requirements of the LT2 rule. In January 2010, the EPA responded indicating that variances are not applicable to the uncovered reservoir requirements of the LT2 rule.

In February 2012, the Portland Water Bureau submitted a detailed request for an extension to its uncovered reservoir compliance schedule. The extension was requested to allow additional time for the Water Bureau to manage the large design and construction contracts that are required to complete the work and was based on a similar request granted to New York City. On May 18, 2012, The Oregon Health Authority rejected the Water Bureau’s request for an extension.

On February 4, 2013, then Commissioner -in-Charge Steve Novick, submitted a revised request for an extension to the uncovered reservoir compliance schedule. The revised request was based on economic and regulatory circumstances cited by the City of Rochester, New York in its successful request for an extension to its own state mandated uncovered reservoir compliance schedule. Congressman Blumenauer also submitted a letter in support of Commissioner Novick’s letter. In April 2013 OHA denied Commissioner Novick’s request.

On June 3, 2013 the Portland City Council announced that, faced with no other legal options and with deadlines looming, the city will move forward to meet the compliance deadline.

The Water Bureau’s existing regulatory schedule to end the use of the uncovered reservoirs by December 31, 2020 remains in effect. To view the Frequently Asked Questions for the Mt. Tabor Reservoir Project, click here.