After Alamosa’s drinking water became contaminated last year, the state of Colorado wisely revoked dozens of waivers that allowed other public drinking water systems to go unchlorinated.
The public health emergency that erupted when salmonella sickened hundreds and killed one person in Alamosa is a harsh reminder of why disinfecting public water supplies is sound public policy — no matter how pure the natural resource may seem.
A 65-page investigative report issued by the Colorado Department of Public Health and Environment analyzes in detail how the contamination could have happened.
It says the most likely cause of contamination was feces from infected animals — perhaps birds — that got inside a 320,000-gallon Weber Reservoir tank that had sizeable cracks and holes in it.
The well water pumped into the tank typically is warm — 75 degrees, even in the winter — so it’s easy to imagine why animals might congregate inside the tank.
The report also spoke to how little fecal matter it takes to contaminate an entire unchlorinated water system. A few birds in the acute phase of salmonella infection may have been enough.
Estimates are that 1,300 people may have been ill during the outbreak, including 40 percent of infants in Alamosa.
Alamosa now treats its water, but those plans were underway even before the salmonella outbreak in an effort to reduce arsenic levels.
In 2008, the state Health Department began a review of waivers for public water supply disinfection.
About 85 percent of the state’s population gets its drinking water from reservoirs, where the water is treated before it reaches the tap.
The untreated systems are pretty small and are generally on the Eastern Plains. They can be used to supply a campground or a filling station in the middle of nowhere.
Untreated drinking water is not a big problem in Colorado. And by that we mean it does not have the potential to affect a vast geographic area or a large number of people.
But as the Alamosa episode clearly demonstrated, such contamination can be easily triggered and quite severe. We’re glad to see the Health Department moving to eliminate the danger from untreated drinking water systems.
