The board of Tacoma Public Utilities (TPU) has a monumental decision to make, one that will have a considerable impact on its residential and commercial customers as well as other water suppliers in the region. Its Tacoma Water division must comply with a federal mandate to treat its water supply from the Green River.
It is aimed at cryptosporidium, a microorganism that poses a high public health threat when it contaminates water systems. Where outbreaks have occurred in other parts of the country, they tended to be in areas where drinking water was at risk because the source was near an area where livestock graze. The risk of an outbreak for Tacoma Water is very low; its source is in the Cascade foothills, far from human or agricultural activity.
Still, TPU must comply with the mandate. After considerable numerous options, two remain - ultraviolet (UV) light disinfection or filtration. Both will cost considerable money, resulting in rate increases. Filtration is the more expensive, with cost estimates of about twice that of UV light.
TPU is to be commended on its considerable public outreach. Dozens of presentations were made to neighborhood councils, businesses and civic groups. While filtration has the heftier price tag, it is emerging as the best choice.
Both options would comply with the federal regulation, but filtration offers several advantages. State and federal agencies often require local governments to comply with policies without providing any funding to do so.
Additional mandates regarding water safety are possible in the future, and filtration would comply with them. Investing in UV light is cheaper but riskier; at some point the state or feds could determine it is inadequate, which would require an additional investment in a filtration system, meaning TPU would have wasted whatever it spent on UV light.
Tacoma Water is a major player in the region, supplying customers far outside the city limits. That role will only grow larger in the future, as utilities in suburban sections of King County purchase water from Tacoma. Kent City Council and the boards of two utility districts have officially declared their preference for filtration.
Of the two options, only filtration would remove dirt and debris, which pose no health threat but can result in cloudy water.
The TPU Board should select the filtration option. This will result in a larger rate increase than UV light, but in the long run it is the wisest investment in the public’s money.
