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In August 2017, Portland City Council voted to build a water filtration treatment facility to meet the treatment requirements for Cryptosporidium. On December 18, 2017, the Portland Water Bureau entered into a Bilateral Compliance Agreement with OHA that establishes a schedule to have filtration operational no later than September 30, 2027.
As the name suggests, filtration is the physical removal of contaminants from water. There are several types of filtration that remove contaminants through varying processes. The type of filtration, capacity of the filtration plant and its location will be factors that determine the cost of the project.
In addition to treatment for Cryptosporidium, there are several benefits to filtration.
Pathogen protection – Filtration removes other pathogens as well as Cryptosporidium, which may allow Portland to use less chlorine disinfection.
Reduced disinfection byproducts – Disinfection byproducts form when chlorine reacts with organic particles. Filtration will reduce the organic particles and may reduce the amount of chlorine, resulting in lowered disinfection byproducts that have known health risks.
Address periods of high turbidity – Currently, the Bull Run Watershed cannot be used when there is elevated turbidity, or sediment, in the water. This can happen during heavy storms or could result from a fire in the watershed. Filtration can remove these sediments, allowing a greater use of the Bull Run.
Reduce taste, odor and color issues – Filtration can reduce some of the common causes of taste, odor and color issues that occasionally occur in Portland’s system. Filtration of algae and lower chlorine levels can reduce taste and odor issues, while reduction of particles can reduce discolored water.
Future Investment – Filtration can potentially address future regulations and emerging contaminants that other Cryptosporidium treatment technologies would not likely address.
Initial estimates for the costliest options for filtration treatment are approximately $500 million. This will increase the average water, sewer and stormwater bill approximately $17 by 2027. A more accurate cost estimate will be available once some of the decisions on the project scope are made in 2018. To assist customers with the projected rate increase, the Portland Water Bureau is also working to enhance the low-income assistance program (LINK).