Oct. 6 Update | Test results clear, but boil advisory still in effect

Published 12:43 pm Monday, October 6, 2014

The City of Mercer Island announced all 18 water-test samples revealed no presence of E. coli or total coliform. The latest samples include seven samples collected with permission from residential properties. However, the boil-water advisory is still in place.

As elevated chlorination spreads ever further through the water mains, and ongoing investigative work continues to rule out many possible sources of water contamination, the multi-agency task force is now discussing the threshold needed to return to normal operations.

The city said in a release crews need to finish the super-chlorinating process and implement the city’s Response Plan to the point where crews have either found the source or ruled out enough possibilities to feel sufficiently confident that if E. coli once existed in Mercer Island’s water system, it is now gone due to the various measures taken.

Yesterday, Seattle & King County Public Health reported a potential case of E. Coli infection in an Island resident. The patient has not been hospitalized.  Lab tests are still pending, and it is not possible to say whether there is any link to Mercer Island water at this point. To report illness to Public Health, residents should call 206-296-4774.

Mercer Island School District plans to continue a regular school schedule using “heat and eat” food and special water procedures, approved by Seattle & King County Public Health. Unless otherwise notified, parents should visit the school’s website at www.mercerislandschools.org for the latest information.

City of Mercer Island and Seattle Public Utility (SPU) crews again collected another 18 samples this morning from the same locations as yesterday for analysis overnight; results will be released by Noon, Tuesday, Oct. 7.

The city reports crews have made notable progress on a number of fronts:

• With help from City of Bellevue and SPU technicians, efforts to propagate water with elevated chlorine levels at concentrations of up to 1.2ppm (parts per million) are progressing well at many locations across the Island. These levels are almost double the standard concentration of chlorine in the city’s water mains.Residents may notice a chlorine smell that can be removed by boiling. This is not harmful to people or animals.
• Chlorine injection resumes today at the reservoir tanks to maintain these elevated concentrations.
• Inspections of 150 underground water pipe vaults is nearly complete, revealing no abnormalities so far.
• 25 key properties in close proximity to areas of interests, and without required backflow device inspections on file, were individually contacted yesterday. Over 200 more second-tier contacts are underway today.

A map of the locations is available at www.mercergov.org/files/Boil-Water_Public_Map_SampleSites_IGS.pdf

If residents have any further questions, please contact the City of Mercer Island hotline, open today from 9 a.m.-5 p.m., at 206-275-7800, or visit the city’s website at www.mercergov.org.