The Arizona Department of Environmental Quality found that Arizona American Water distributed drinking water contaminated with excess levels of arsenic at its Tubac Valley public water system in Santa Cruz County during February 2009. Arizona American is a subsidiary of American Water.

Test results submitted by Arizona American to ADEQ from February 9, 2009 showed arsenic up to three times the “maximum contaminant level” under state and federal regulations. In July 2009, the company signed a consent order with ADEQ agreeing to install a treatment system for Tubac Valley to reduce arsenic levels below the permissible limit.

The previous year, ADEQ found that Arizona American distributed drinking water contaminated with trichloroethylene (“TCE”) to customers in Scottsdale and Paradise Valley. An equipment malfunction at a treatment plant operated by the company allowed groundwater contaminated with TCE to be pumped into the drinking water system for up to 16 hours on January 15-16, 2008. Tests showed that TCE levels were up to four times the legal limit.

The contamination resulted in Arizona American warning its nearly 5,000 customers in Scottsdale and Paradise Valley not to drink or cook with the tap water for three days, until TCE levels were reduced to below the permissible limit. ADEQ also found that on January 17, the company flushed TCE-contaminated water from its system by discharging tainted water into municipal streets and storm sewers without a permit.

The January 2008 events occurred only three months after another incident involving TCE-contaminated water at the same Arizona American facility.

In October 2007, “incomplete remediation” of TCE-contaminated groundwater occurred during a week-long maintenance operation at the plant, according to a consent order subsequently issued by ADEQ in the case. The malfunction resulted in the delivery of water in excess of the maximum contaminant level to the company’s Paradise Valley arsenic removal facility. Arizona American failed to notify ADEQ about the event until approximately one month later, within 24 hours of the company receiving lab results for TCE samples taken on October 15.

TCE levels in the 2007 incident were reduced to below the permissible limit before the water reached customers’ taps, since the company had “blended” the contaminated water with other sources of water prior to distributing it into the drinking water system. Even so, ADEQ cited Arizona American in the case for failing to properly maintain its treatment facilities and for failing to notify either the state agency or the public in a timely manner concerning the incident.

In March 2008, ADEQ issued a consent order imposing a $69,000 fine against the company for the October 2007 and January 2008 incidents. In a press release announcing the order, ADEQ’s director strongly criticized Arizona American’s conduct in the case:

“The company delivered contaminated drinking water to its customers, failed to maintain and operate its facilities to deliver safe drinking water, and failed to implement an adequate emergency plan. This is simply unacceptable.”

The order also required the company to prepare a report describing the events leading up to the incomplete treatment of TCE-contaminated water in the two cases. That report – issued in April 2008 by a consulting firm hired by Arizona American – identified numerous problems at the treatment plant.

Among other issues, the report found that “several of the instruments installed to provide data and control of the valves, blowers, and other mechanical equipment were found to be either severely out of calibration or not functioning at all.”

The World Health Organization classifies TCE as “probably carcinogenic to humans.” According to the U.S. Environmental Protection Agency, some people who drink water containing TCE well in excess of the maximum contaminant level for many years could experience problems with their liver and may have an increased risk of getting cancer.

Long term exposure to arsenic has been linked to cancer of the bladder, lungs, skin, kidneys, nasal passages, liver, and prostate, according to the EPA. The EPA states that some people who drink water containing arsenic well in excess of the maximum contaminant level for many years could experience skin damage or problems with their circulatory system, and may have an increased risk of getting cancer.