Final Report on Alamosa Drinking Water
Disease Outbreak Released
DENVER – The Colorado Department of Public Health and
Environment today released its final report regarding the Salmonella
outbreak that struck Alamosa in 2008. The outbreak resulted in hundreds
of people in the community becoming ill and had a significant economic
impact on the city.
By the time the outbreak subsided, there were 442 reported cases of
illness, typically involving vomiting and diarrhea. There was one death
associated with the outbreak. Overall, state health experts estimate
that up to 1,300 people may have been ill in the town of 8,900. For
about three weeks during the outbreak, Alamosa residents were advised to
drink bottled water or boil their water, and many businesses temporarily
closed.
The health department’s final report provides a comprehensive look at
the disease outbreak, the response to the outbreak, and the conclusion
of the 18-month investigation into how the city’s drinking water became
contaminated. The investigation involved a detailed review of the water
system; historical records; and interviews with city of Alamosa
personnel, local health officials and responders to the outbreak.
“We believe the people in Alamosa deserve to know what happened, what
was done about it and why it happened,” said Ron Falco, Safe Drinking
Water program manager in the Water Quality Control Division at the
department.
The 65-page report concludes that animal waste most likely contaminated
a concrete in-ground water storage tank that had several holes and
cracks. A water sample collected during the outbreak indicated that
water in the tank contained bacteria. Additional site visits conducted
in 2009 found animal footprints in the snow around the tank, and a
photograph in July 2009 captured bird feces on a corner of the tank that
was repaired at the time of the outbreak. While these observations were
made in 2009, they likely are representative of the animal activity that
could have contaminated the water supply in the tank in 2008.
“We cannot say with absolute certainty where the Salmonella came from
because the actual contamination event was not directly observed, and
probably occurred at least seven to 10 days before the outbreak was
reported,” Falco acknowledged. “But after weighing all the evidence, we
believe that the most likely scenario is that contamination entered this
in-ground storage tank.”
The city commissioned an inspection of the in-ground storage tank in
July 1997 by a professional tank inspection company. That inspection
report noted cracking and problems with the corners of the tank, and
recommended routine inspections for the future. It appears that the tank
continued to deteriorate into 2008. The state did not know of the city’s
1997 inspection findings, and its own inspections did not focus on
storage tanks and distribution piping.
Alamosa was granted a waiver from state requirements to disinfect its
drinking water in 1974, so water being served to the public in Alamosa
at the time of the outbreak was not chlorinated. The investigation
showed that only a small quantity of bird or animal feces contamination
may have led to the salmonella outbreak. This kind of outbreak may have
been very difficult to prevent in a system that did not chlorinate its
water.
The state is continuing its review of all public drinking water systems
with disinfection waivers, and has withdrawn 72 of them since the
Alamosa outbreak. “This incident further underscores the long-accepted
public health benefits associated with disinfecting drinking water,”
said Falco. “Chlorine is a highly effective means of destroying bacteria
such as Salmonella.”
The report also highlights how the department’s Safe Drinking Water
program historically has had staffing and funding challenges since its
inception in the 1970s. Some new staff have been added to the program
since the outbreak, but resource problems continue, with few solutions
available during the current economic downturn. The Safe Drinking Water
program is prioritizing the use of resources to enhance inspections of
water storage tanks, escalate enforcement for systems that fail to
correct problems found during inspections, and develop training to help
water systems optimize storage tank and distribution piping operations
and maintenance.
“I was very pleased with the department’s response to the Alamosa
Salmonella outbreak,” said Chief Medical Officer Ned Calonge, interim
executive director of the department. “Many, many employees from the
department’s environmental and public health divisions, as well as
additional individuals in other state and local agencies teamed up to
assist Alamosa in addressing its crisis as quickly as possible.”
The report has been posted to the department’s Web page, along with a
photograph slide show and video at:
http://www.cdphe.state.co.us/wq/drinkingwater/AlamosaOutbreak.html
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State of Colorado,
Department
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