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The Environmental Protection Agency announced it will develop a regulation for perchlorate. According to EPA: "Perchlorate is both a naturally occurring and man-made chemical, and scientific research indicates that it may impact the normal function of the thyroid, which produces important developmental hormones. Thyroid hormones are critical to the normal development and growth of fetuses, infants and children."


While it is not regulated in Colorado, Denver Water tested its drinking water for perchlorate as early as 1997. Additional testing has been done since 2002, with most of the results being below the reporting level (reporting level means the lowest level the labs can accurately report). The current reporting level is 0.05 ppb (parts per billion or micrograms per liter), although it has been higher in the past. There has been only one test result that was significantly higher than the reporting level — a value of 0.68 µg/L in 2004. For comparison, California has a regulation of 6.0 µg/L, nearly 10 times higher than those results.

What this means for us

If perchlorate regulations are imposed, they are not likely to have an impact on Denver Water because systems fed from groundwater or wells typically experience problems with perchlorate. Denver Water has a surface water system that comes from snowmelt or precipitation.