Police officers stand watch outside the Rocky Mountain Regional Trauma Center after a shooting at a motorcycle show at the National Western Complex in Denver, Colorado Jan. 30, 2016. Reuters

The Denver Sheriff Department will pay a $10,000 fine for refusing to hire non-citizens as deputies between 2015 and 2016. Colorado’s largest sheriff’s department reached the settlement agreement with the Department of Justice Wednesday after it was caught illegally posting job ads requiring applicants to have U.S. citizenship.

Under the anti-discrimination provision of the Immigration and Nationality Act, The Denver Sheriff Department was obligated to equally consider immigrants when searching for applicants if they had valid work permits, according to a statement from the Justice Department Monday.

The Justice Department is requiring the Denver Sheriff Department to comb through non-citizen job applicants between Jan. 1, 2015 and May 23, 2016 and reconsider their qualifications without regard to their citizenship. The Denver Sheriff Department was also ordered to retrain its staff and review its policies on anti-discriminatory hiring practices.

Beginning in Junuary 2015, the department hired 200 deputies to address its needs for a bigger staff and to reduce the millions of dollars it was spending on overtime salaries, the Denver Post reported Monday. Because citizenship was a stated requirement for the job on the application, everyone hired was American.

“We commend the Denver Sheriff Department for its cooperation and commitment to removing unnecessary and unlawful employment barriers,” Principal Deputy Assistant Attorney General Vanita Gupta, head of the Justice Department’s Civil Rights Division, said in the statement. “Eliminating this unlawful citizenship requirement will help ensure that the Denver Sheriff Department hires the best and most qualified individuals to protect and serve. The entire community will benefit from these reforms.

While more than 40 states have legislation in place allowing police departments to impose hiring limitations based on citizenship under federal law, Colorado, Louisiana, Maine, Vermont and West Virginia have no such rules restricting non-citizens from being police.

The Justice Department similarly fined the Eugene, Oregon, police department a $3,000 civil penalty and mandated it to retrain its employees in August 2015 after it was caught trying to bar non-citizens from law enforcement positions by asking police officer applicants about their citizenship status, Reuters reported Aug. 5, 2015.

In a statement, Simon Crittle, a spokesman for the Denver Sheriff Department, said the roughly 890-member department was unaware that their hiring practices had broken federal laws, according to the Associated Press Monday.

"While we didn't commit this violation intentionally, we accept responsibility and are taking steps to clarify policy and amend language in hiring documents," said Crittle in the statement.

Ira Mehlman, spokesman for the Federation for American Immigration Reform, a non-profit organization based in Washington D.C., committed to improving border security and stopping illegal immigration, told Fox News that hiring non-citizens who have temporary work permits would not be financially sustainable for police departments.

“They’re (the police force) making a long term investment, paying for training, for someone who might be ineligible to work in a few years,” Mehlman told Fox News.