Questions & Anwers

History
In 2010, the City of Tacoma Public Utility Board selected the water filtration method to address a new regulation (Long Term 2 Enhanced Surface Water Treatment Rule [LT2]) that requires us to treat the water supply for a naturally occuring microorganism called cryptosporidium.

Levels of cryptosporidium remain low in the Green River water supply. We do not currently have any issues with this organism. However, we must comply with the new laws by 2014.

Two effective treatment options for this organism include filtration and ultraviolet light disinfection. In 2010, Tacoma Water, its policymakers and customers evaluated and weighed the cost, benefits and risks of building a filtration plant against the more moderate cost and lesser benefits of ultraviolet light treatment.

Reccommendation for Green River Water treatment
Memorandum

Water Treatment Evaluation and Decision Process
Final Summary Report
By HDR with CH2MHILL