Colorado farm town copes with presence of salmonella in water; treatment makes it unusable

Hundreds were lining up in grocery stores for bottled water after learning that salmonella had contaminated the water supply in their farm town.

They stocked their freezers with microwavable food such as burritos and chili. They bought paper plates and cups. When schools closed, they entertained their children at home.

More than 300 of Alamosa's 8,500 people have been sickened since the first victims showed symptoms on March 7. Some 73 cases have been confirmed, with 11 people requiring hospitalization. Half the victims have been under age 11.

Salmonella can cause diarrhea, fever and stomach pain. Victims typically recover on their own, though infants, the elderly and those with impaired immune systems may require treatment.

State health officials did not confirm the outbreak until March 20. Salmonella is usually a food-borne disease and contamination of public water systems is rare.

The particular strain that caused the outbreak is one found in the feces of local deer, birds and other warm-blooded animals. How it got into the water remains a mystery.

The search for the source is frustrating, City Manager Nathan Cherpeski said.

"As we get evidence, it will start to appear we have the source. But at the end of the day we start to have evidence it's something else," he said.

Between 1971 and 2004 there have been 15 salmonella outbreaks in municipal water systems, said Jonathan Yoder, a waterborne epidemiologist with the Centers for Disease Control, which tracks such incidents.

Of the five cases since 1985, two involved cracked pipes or problems in the distribution system, Yoder said. Two more were blamed on insufficient water treatment. The other was attributed to untreated ground water.

In Gideon, Missouri, in 1993, bird feces was determined to be the probable cause after bird feathers were found floating in a water storage tank, said Steve Gunderson, director of Colorado's water quality control division.

But officials never determined the source of a 1965 outbreak in Riverside, California, that affected 16,000 people.

Alamosa draws its water from a deep well and is the largest Colorado water system not required to chlorinate its water, Gunderson said.

Plans to change that were under way before the outbreak. A US$16 million (euro10 million) water treatment plant will come online this summer. It was built after arsenic levels in city water exceeded Environmental Protection Agency standards.

To deal with the salmonella outbreak, however, officials were now pumping heavy doses of chlorine to clean from the water system — rendering the water unusable for anything but flushing toilets.

Signs were posted outside town on Tuesday to warn that the water was unusable.

National Guard troops distribute bottled water from trucks. A water tower looms over a dusty main street lined with mom-and-pop shops in the San Luis Valley.

Gas stations no longer offer coffee or soda from fountains. Main restaurants such as Hunan Chinese Restaurant advertise a free bottle of water with meals, rather than daily specials. Anti-bacterial hand sanitizing gels are in heavy demand. And fresh vegetables are no longer available at the city's three grocery stores because they cannot be rinsed.

The Comfort Inn, which has its own, uncontaminated well, opened several rooms to allow residents to shower.

Others tried to cope as best they could.

"We'll see what we're made of," said Gary Wuckert, an apartment manager, who filled his bathtub before the heavy chlorination began.

City officials were hoping chlorine levels would drop enough this weekend to allow residents to at least bathe again.

Once the entire system has been disinfected, which is expected to be completed April 7, officials plan to leave a residual amount of chlorine in the water to prevent future contamination.