A watchdog arm of the U.S. Department of Veterans Affairs said Thursday that the agency's Denver hospital violated department policy by keeping improper wait lists to track veterans' mental health care.

Investigators with the VA Office of Inspector General confirmed a whistleblower's claim that staff kept unauthorized lists instead of using the department's official wait list system. The report says that made it impossible to know if veterans who needed referrals for group therapy and other mental health care were getting timely care.

The report drew a sharp rebuke from Colorado Senator Cory Gardner, one of several lawmakers to request the investigation. In a statement released to the media, the Republican said his “worst fears” had been realized. The senator added that it’s time for the VA to “finally wake up and ensure our men and women are getting the best care possible.”

The VA hospital also released a statement, saying it concurred with the findings presented by the Office of Inspector General but it did not agree with the characterization that unofficial wait lists were secret wait lists.

The hospital explains it used “interest trackers” to gauge potential demand for a number of mental health groups among veterans who were already receiving therapy from a VA medical provider. They were intended to allow mental health providers to gather enough patients to begin group therapy. The office says it stopped using interest trackers after learning they were not allowed under VA scheduling policy.

The Denver facility says it welcomes the OIG’s findings and recommendations as an additional check to ensure veterans are receiving the highest-quality care.