D.C. Council member Jack ­Evans repeatedly used his office on behalf of private clients who paid him hundreds of thousands of dollars, failing to recognize the conflicts and never properly disclosing the payments, according to an investigation by a law firm hired by the council.

The confidential report by O’Melveny & Myers, distributed Monday to lawmakers and reviewed by The Washington Post, identified 11 instances since 2014 in which Evans violated the council’s rules governing ethics.

It marks the first time the D.C. Council has detailed ethical lapses by Evans, the Ward 2 Democrat and the city’s longest-serving lawmaker. His business interests and his public actions have been the target of a federal investigation, as well as a probe by the Washington Metropolitan Area Transit ­Authority.

But a majority of D.C. Council members had been reluctant to investigate their colleague until this summer, after a law firm hired by WMATA concluded that Evans had violated a Metro ethics rule while serving as chairman of its board. Evans resigned from the Metro board, and the D.C. Council stripped him of the chairmanship of a powerful committee and decided to conduct its own review of his activities in the past five years.

As a council member, Evans “repeatedly participated in his official capacity in ‘particular matters’ in which his outside employers or his personal clients had direct financial interests, failing to recognize the inherent conflict that should have been disclosed and addressed,” O’Melveny & Myers concluded.

“He received over $400,000 for doing little or no documented work for consulting clients most, if not all, of whom were also ‘prohibited sources’ under the Code of Official Conduct,” the report said.

Reached Monday night, Evans disputed the law firm’s findings and said his conduct was appropriate. He said his legal team, which had access to the report over the weekend, planned to ­issue a detailed 40-page response Tuesday.

Investigators found no ethics violations in at least eight other instances of potential conflicts examined by the firm. For example, they found Evans did not break rules prohibiting lawmakers from using staff for non-council functions when he had his chief of staff spend “limited” time on his consulting business.

Evans, who has worked for several prominent local law firms, formed his own consulting company in 2016. He contracted with 10 entities, “mostly local busi­nesses owned by Evans’s close friends or acquaintances,” the report said.

D.C. lawmakers earn about $140,000 and are permitted to have outside employment but are required to avoid conflicts of ­interest.

The firm’s 97-page report detailed instances in which Evans took official action that affected the financial interests of his clients and employers.

Among the findings:

●Evans repeatedly acted to support a controversial merger between Pepco and Exelon while he was negotiating for a job at Manatt, Phelps & Phillips, a law firm handling the merger of the utilities. He suggested to Manatt that he could sign Exelon as a client and later got the job. Evans said his actions were appropriate because he pushed for the merger before starting work at Manatt.

●Evans, while representing the parent company of Colonial Parking, used his legislative position to block the mayor’s proposed tax increase on commercial parking lots. Evans said he has consistently opposed increases on parking lot taxes.

●Evans and his staff repeatedly assisted the development company Willco in dealing with issues at city agencies, including speaking to a senior official in the mayor’s office to find out if the city government was going to renew a lease on a Willco property.

●Evans arranged for a meeting with his consulting client EastBanc Technologies and city officials to “pitch software initiatives that might lead to city contracts.”

●Evans also arranged for his clients EastBanc and Willco to meet with council member ­Kenyan R. McDuffie (D-Ward 5) to discuss potential projects in his district.

According to the report, Evans told investigators that these actions were motivated by the public interest rather than his paying clients. Evans told The Post that arranging meetings with officials and assisting Willco with city agencies amounted to constituent service work that his office would provide for anyone.

The firm also found that Evans failed to disclose his clients, as required by council rules, and gave contradictory explanations. Evans told investigators that he relied on his staff to identify potential conflicts of interest but also conceded that he didn’t disclose his clients to his staff, the report says.

All but one of Evans’s consulting clients refused to speak to investigators, most invoking their Fifth Amendment rights against self-incrimination. One client, former EagleBank chief executive Ron Paul, said health issues precluded him from being interviewed.

Colonial Parking chief executive Russell “Rusty” Lindner told investigators he understood that retaining Evans’s consulting firm was a way to purchase “greater license for [him] to take Jack’s time” and to “use him as a sounding board.”

“The investigation identified no evidence of ‘deliverables’ — e.g., written reports to clients on business or political trends or developments, advice on specific projects, or introductions to landlords or other business partners,” the report says. “According to Evans, his clients were mostly paying for the value of having him available on short notice if he could be helpful.”

The rest of the 13-member council is planning to meet in two weeks to review the report and question the investigators.

The council has several options for discipline, including a reprimand or censure. It could also strip Evans of all committee assignments, a measure that failed on a deadlocked vote over the summer.

A federal grand jury has issued subpoenas for documents related to Evans and his clients, and FBI agents searched the lawmaker’s Georgetown home in June. Evans says he has spoken to federal prosecutors, but he has not been charged with a crime.

He also faced repercussions for using his government email account to solicit employment from local law firms. In the emails, he touted his influence as an elected official and chairman of the Metro board as a reason to hire him. The D.C. Board of Ethics and Government Accountability in August fined Evans $20,000 for misusing the city’s email system.

Evans has also faced political fallout from his ethics scandals. He has drawn six challengers in the June 2020 Democratic primary — his first electoral opposition in a decade — and some activists are collecting signatures to force a recall election.