State and Portland city officials have agreed on a compliance schedule that outlines how the city plans to build and construct a water filtration plant in the Bull Run Watershed that will treat water for the parasite cryptosporidium.

The agreement marks the official end of a variance that made Portland the only city in the country that didn’t have to treat its water for the parasite. 

“The variance was the only one of its kind,” said Edward Campbell, the resource protection and planning director with the Portland Water Bureau.

“We finally, over the course of this year, detected far too many cryptosporidium for us to maintain the variance. So that’s why we’ve come to this form of compliance now.”

The city has about 10 years to build and begin operating a water filtration plant in the Bull Run Watershed. Water that’s treated for cryptosporidium will be served no later than Sept. 30, 2027.

The Portland Water Bureau is scheduled to submit a plan outlining details such as design, location and filtration type by 2020.

In August, Portland City Council voted unanimously to move toward building a water filtration plant that could cost the city up to $500 million. 

The Oregon Health Authority granted the Water Bureau three deadline extensions, giving the city time to finalize its compliance schedule.

“We think we’ve come to an agreement that serves the best interest of public health both immediately and then across the next decade, and that we’ve really strengthened our relationships with our public health partners and we’re glad for that,” Campbell said.