June 5 (Reuters) - Environmental groups filed notice on

Wednesday to sue Canadian oil producer Suncor Energy ( SU )

under the U.S. Clean Air Act for repeated air pollution

violations at its Commerce City, Colorado, refinery.

The organizations, represented by environmental law

non-profit Earthjustice, said they will bring a civil suit

against Calgary-based Suncor over more than 1,000 emission

violations that Earthjustice said Suncor reported to the state

of Colorado between January 2019 and December 2023.

Under the Clean Air Act, members of the public must give 60

days' notice to the entity they intend to sue before filing a

lawsuit.

Commerce City near Denver has Colorado's only refinery,

processing 98,000 barrels of oil per day.

The facility has been dogged by problems in recent years

including a fire in December 2022 and complaints from residents

about air-quality issues.

"If someone was given 1,000 speeding tickets, we'd take away

their license," said Margaret Kran-Annexstein, director of

Colorado Sierra Club, one of the groups that intends to sue

Suncor.

Suncor has said it is implementing improvements to address

the refinery's emissions as part of a 2020 settlement with

Colorado's public health and environment department.

Ian Coghill, a senior attorney with Earthjustice, said the

groups are seeking civil penalties from Suncor and to deter the

refinery from further air pollution violations.

"The state has taken action against Suncor but it doesn't

seem to have changed anything," Coghill said. "What we're

looking for is to hold Suncor accountable and (find) meaningful

deterrents to bring Suncor into compliance."

Coghill said the maximum penalty for every day of violation

under the Clean Air Act is up to $121,000 and the suit is

alleging 9,000 days of violations.

In February the state of Colorado fined Suncor $10.5 million

for violating air pollution laws between 2019 and 2021.