From The Pueblo Chieftain (Chris Woodka):
esting was performed by MWH Labs, which can test for levels as low as 0.05 parts per billion. “You wouldn’t expect to find it in our water supply, since it’s usually found in groundwater,” Colalancia said. The water board last month learned that a lower threshold for chromium 6 testing is being considered by the Environmental Protection Agency. The water board has tested water routinely for total chromium in the past, with results well below standard limits. The national standard is 100 ppb for total chromium and Pueblo always has tested below 4 ppb.
More water pollution coverage here.