Last week, residents received a letter from the city regarding progress made in strengthening and improving the Island’s potable water delivery system since the E. coli contamination and boil-water advisories last fall.
The city was supposed to provide an update on the response to the water situation at the Council meeting on March 16, but that was pushed back in the planning schedule to March 30 to finish up the discussion on the moratorium in Town Center.
Since the boil water advisories, city crews have maintained elevated chlorine levels throughout the water system, as strongly recommended by the state Department of Health (DOH), while continuing to search in every direction for the cause of the contamination. The root cause has not yet been identified.
Soon, crews will be building nine new monitoring stations — in addition to the city’s existing five — to provide more accurate data on what’s happening inside the water supply system, as well as replacing the plumbing in 60 underground vaults.
Staff will also be contacting households with plumbing connections, such as yard irrigation or fire sprinklers, that could potentially allow dirty water to enter the clean side of the system.
Any cross-connection with the city’s water system represents a potential pathway for contamination. Staff is scheduled to present a cross-connection control program code update to the Council on May 4.
Mercer Island’s cross-connection control program was adopted in 1985, and hasn’t been updated since. It requires backflow prevention devices to be installed and annually tested wherever a cross-connection exists, such as with irrigation systems, especially those using lake or reclaimed water.
The added water supply system maintenance work will be funded by an increase in the city’s water utility rates. They went up 12.8 percent on Jan. 1 of this year.
For a typical homeowner, the total bimonthly utility bill (including water, sewer, storm water and emergency management systems) will increase eight percent, or $21.41, in 2015.
