Giardia
Giardia is a microscopic organism found in most untreated surface water. The Las Vegas Valley's water supply has been tested regularly for this organism since 1994.
Giardiasis, the illness associated with this pathogen, may cause severe diarrhea, abdominal cramps, malaise and weight loss. Vomiting, chills, headache and fever can occur in more serious cases. Giardiasis may pose a serious health risk to individuals with severely suppressed immune systems.
One of the most effective safeguards against Giardiasis is ozonation, a water treatment process which uses ozone to eliminate biological organisms. The Southern Nevada Water Authority's Alfred Merritt Smith and River Mountains water treatment facilities, which treat the majority of our water supply, incorporate ozonation into their treatment processes.
Giardiasis outbreaks occur more frequently in the northeast and northwest, possibly due to the extended winter season and low surface water temperatures. Most community outbreaks occurred in water systems with minimum treatment to its surface water source.
A giardiasis outbreak usually occurs when conditions include low water temperatures, poor sanitation upstream, beaver colonies (or other ground animals such as muskrat) located near the water supply intake and inadequate water treatment.