A stormwater flood at Suncor Energy’s refinery in Commerce City last week leaked benzene into the Burlington Ditch where it flows through the Denver’s wastewater treatment plant property, but state health officials say pollution levels did not threaten human health or drinking water.

Low levels of benzene were found in water samples taken by Suncor, according to a Colorado Department of Public Health and Environment news release. Suncor’s samples reported benzene levels at 0.18 micrograms per liter, and the permitted level for benzene is 5 micrograms per liter.

The Water Quality Control Division sent a stormwater permit inspector to test the water and confirm Suncor’s self-reported findings.

“The current flooding at the facility seems not to have caused a public health risk, but we will continue to monitor the situation and update everyone accordingly,” Trisha Oeth, CDPHE’s director of environmental health and protection, said in the news release.

Suncor contained the remaining stormwater on its property and will test it before releasing it into the water system.

The stormwater flood contaminated the Burlington Ditch where it flows through Metro Water Recovery, where wastewater is treated for 61 local governments, including Denver and parts of Adams, Arapahoe, Jefferson, Douglas and Weld counties.

In January, Suncor released excessive levels of benzene into Sand Creek during a nearly three-month shutdown caused by a late December cold snap. During that incident, Suncor notified the state that its benzene levels were 40% to 80% above permitted allowances.

Benzene is a chemical naturally found in crude oil and gasoline that can cause blood diseases, cancer and menstrual irregularities through long-term exposure.

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