WASHINGTON — The Coast Guard has fostered a poor environment for women and minority cadets and has failed to fairly investigate harassment by senior officers and to prevent retaliation against people who report bullying, a House committee said Wednesday.

The report, by the House Oversight and Reform and Homeland Security Committees, accused the service of “leadership failures and a lack of accountability,” and was based on thousands of documents and interviews with Coast Guard personnel. The investigation focused on how the maritime agency handled two reports of harassment at the Coast Guard Academy, including one made by an instructor who identified as black and lesbian who said she was discriminated against and bullied by the agency’s leadership.

The inspector general for the Department of Homeland Security, which houses the Coast Guard, had found last year that the former instructor, Lt. Cmdr. Kimberly Young-McLear, received low marks on a performance evaluation in 2016 because she came forward with complaints of harassment. She now works on cybersecurity at the department. The report concluded that in retaliating against her, the Coast Guard violated the Military Whistleblower and Protection Act.

“Ultimately, the Coast Guard failed to provide a safe working environment and failed to hold those responsible accountable despite evidence of wrongdoing and knowledge of our culture,” Ms. Young-McLear said, according to her opening remarks for a joint House hearing on Wednesday. “The psychological, emotional and financial toll this has had on my wife or me cannot be overstated.”