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Suncor Energy’s Commerce City plant is seen Feb. 17, 2023. (Olivia Sun, The Colorado Sun via Report for America)

State regulators have warned Suncor of possible fines from “significant noncompliance” that poured benzene-tainted water into Sand Creek at up to 160% of permitted levels in repeated leaks this year, records show. 

“Due to the severity and/or persistence of these violations, the Water Quality Control Division is initiating a process to determine whether a formal enforcement action is warranted,” a mid-June letter from the division to Suncor said, with potential fines of more than $61,000 a day. 

Colorado regulators also said discharge incidents of PFAS “forever chemicals” from Suncor into the creek continue to drive potential revisions to Suncor’s water discharge permits, which require renewal. 

“We remain focused on issuing a permit that holds Suncor accountable, requires Suncor to monitor and limit PFAS discharges and provide information when requested,” said division spokesperson Kaitlyn Beekman, in response to an environmental group noting repeated Suncor reports of PFAS discharges well above new EPA limits. 

Earthjustice, which has been monitoring Suncor’s reporting of water discharge analysis to the state, welcomed the potential cease-and-desist violations for benzene, calling Suncor’s problems a long pattern of polluting air and water in north Denver, Commerce City, and downstream of the Sand Creek and South Platte River confluence. 

The Forever Problem

“Forever chemicals,” or PFAS, are an increasing toxic burden on Colorado. We’re committed to covering the public health threats, from water and croplands to the costs to clean them up.

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“It shows the division is really looking to take this seriously,” said Caitlin Miller, an Earthjustice attorney in Denver. “I was really happy to see some of the strong language that they used.” 

Groundwater tests underneath and around Suncor, the only gasoline refinery in Colorado, show a plume of tainted water moving away from the facility and toward local waters like Sand Creek and the South Platte. Suncor pumps water up from the groundwater and runs it through treatment before discharging it into Sand Creek. 

Suncor reported a major fire and shut down operations entirely at the end of 2022. Suncor’s reports to the state indicate the fire and firefighting liquids overwhelmed the treatment system, Miller said, leading to the excess discharges. 

A January discharge of benzene was at 13 parts per billion, or an exceedance of 160% over the permit cap, the state’s letter says. Different days in April saw discharges of benzene at 60% and 100% over the cap. The state also lists two other violations in April for “suspended solids” in the discharge water, at 23% and 24% over the cap for those materials. 

Suncor did not respond to repeated requests for comment last week.

Earthjustice has noted other exceedances in Suncor reports that were not part of the June state discipline letter. Independent engineers have faulted the refinery’s upkeep and maintenance of complex equipment. 

“Suncor needs to make sure that it is properly maintaining all of the equipment at the site and its treatment systems so that they are actually working effectively,” Miller said. “Seven different accidents, or seven days of exceedances already this year, that’s a lot.” 

The state action on benzene follows news that discharges of water tainted with PFAS “forever chemicals” from the Suncor refinery spiked again in May, following high readings in November and January. 

Suncor, which has used firefighting foam containing PFAS chemicals for years on the sprawling Commerce City property, reported May discharges into Sand Creek at 218 parts per trillion of variants of the chemicals known as PFOS, PFOA and PFNA, according to Earthjustice attorneys. 

Immediately after leaving Suncor, the discharged water is carried by Sand Creek into the South Platte River as it flows through Adams County. The May discharge peaks were more than three times the PFAS limits proposed in a 2022 draft renewal permit written by state regulators to cover Suncor’s water discharges. 

The thousands of variations of PFAS chemicals are used in countless consumer and industrial products for water and stain resistance, among other functions. They were used for decades in everything from carpet to firefighting products to clothing and fast-food packaging, though manufacturers are trying to phase them out of many products and states like Colorado are banning them. States’ attorney general offices, including Colorado, are suing manufacturers like 3M and DuPont to recover water filtration and ground cleanup costs. 

Until March, the EPA’s drinking water guideline — not a mandate to water agencies, but health guidance — had been limiting PFAS to 70 parts per trillion. Then the EPA issued sharply lower levels that are now drinking water mandates that cities must achieve, setting them as low as 0.02 parts per trillion for the variant PFOS, and 0.004 ppt for PFOA.

Earthjustice had previously flagged Suncor refinery releases of PFAS. One outflow measured at Suncor found November readings at 1,100 parts per trillion of PFOS in discharges, or 55,000 times the downward-revised EPA requirements. Discharges of 54 parts per trillion of PFOA that month were 13,500 times the new EPA limits on that chemical, Earthjustice said. 


Benzene, present in petroleum as well as other natural substances, is colorless or light yellow at room temperature, according to the CDC. “It has a sweet odor and is highly flammable,” the CDC says. 

“The major effect of benzene from long-term exposure (a year or more) is on the blood,” the CDC adds. “Benzene causes harmful effects on the bone marrow and can cause a decrease in red blood cells, leading to anemia. It can also cause excessive bleeding and can affect the immune system, increasing the chance for infection.” 

PFAS chemicals have been produced since the 1940s. Some versions do not break down over time and have been shown to contribute to human health problems including low birth weight babies, high cholesterol, compromised immunity, increased cancer risk and infertility.

Michael Booth is the Sun’s environment writer, and co-author of the Sun’s weekly climate and health newsletter The Temperature. He is co-author with Jennifer Brown of the Colorado Book Award-winning food safety investigation “Eating Dangerously.” Booth was part of teams that won two Pulitzer Prizes for breaking news. He also writes frequently about inexplicable obsessions that include tamarisk, black-footed ferrets and tire fires. Booth also serves as the underpaid driver for four children, and plans to eventually hike every inch of Colorado.