Nearly 150 unauthorized workers have been accounted for among three businesses in Colorado following workplace audits, resulting in more than $8 million in fines.

U.S. Immigration and Customs Enforcement said its Denver office issued a notice of intent to fine CCS Denver, Inc.; PBC Commercial Cleaning Systems, Inc.; and Green Management Denver.

The fines are a result of "widespread employment eligibility violations," ICE said.

The largest fine – $6,186,171 – went to CCS Denver after ICE discovered a 100% substantive violation rate and evidence of knowingly hiring and employing at least 87 unauthorized workers.

PBC Commercial Cleaning Systems had a 74% violation rate and at least 12 workers were hired and put to work without proper credentials, resulting in a fine of $1,599,510.

Green Management Denver was fined $270,195 after 44 authorized employees were identified, along with a 100% violation rate.

"The employment of unauthorized workers undermines the integrity of our immigration system and puts law-abiding employers at a disadvantage," said Special Agent in Charge Steve Cagen. "These penalties reinforce our commitment to uphold the law and promote a culture of compliance."

Homeland Security Investigations said its worksite enforcement efforts focus on making sure businesses are following federal employment laws, especially with I-9 audits, civil penalties and criminal prosecution.

HSI said a three-prong approach of Compliance, Enforcement and Outreach is the most efficient way to handle worksite enforcement.