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A malfunctioning valve has prompted a boil-water notice for customers of the Black Mountain Irrigation District.

The valve regulates the flow of treated water into the distribution system from Mission Creek. But, its failure is preventing the valve from opening sufficiently to meet increased seasonal demand.

To maintain adequate water supply to the district, it is necessary to bypass the water treatment plant and use untreated water directly from the creek, BMID says.

The water quality in Mission Creek is particularly poor at the moment, due to spring runoff.

Tap water used for drinking, brushing teeth, or rinsing foods should be brought to a rolling boil for one minute.

The advisory is in effect until further notice.

BMID says it will take about two weeks to repair the valve, refill reservoirs and flush out the distribution system with treated water.