Sen. Al Franken (D-Minn.) gave a farewell address at the Capitol Thursday. (Andrew Harnik/AP)

Only one claim of sex discrimination or harassment was settled by a senator's office using a controversial Treasury Department fund over the past 20 years, according to data released Thursday.

Claims of age discrimination drove the largest number of settlements involving senators' offices from 1997 until this year, playing a role in eight of 13 agreements, the data showed.

The disclosure represented the Senate's first effort to be transparent about its taxpayer-funded settlements since the arrangements began receiving scrutiny this fall. The House has revealed that its member-led offices were involved in 21 workplace settlements between 2008 and this year, with at least 10 involving allegations of sexual harassment or sex discrimination.

The 13 settlements involving senators' offices cost $599,252, according to the information released by the Senate Committee on Rules and Administration. The parties involved in the agreements were not revealed.

Settlements involving claims of age discrimination cost $286,786; one agreement alone cost $102,903. The single settlement addressing allegations of sex discrimination or harassment cost $14,260. Congress has not traditionally separated claims of sexual harassment from sex discrimination in its record-keeping.

Senate Rules Committee Chairman Richard C. Shelby (R-Ala.) had expressed concerns about the reliability of the data, which was provided by the Office of Compliance. But he said that the Senate's attorneys approved his decision to release it.

Sen. Al Franken (D-Minn.) gave a farewell address at the Capitol on Thursday. (Andrew Harnik/AP)

"Harassment in the workplace should not be tolerated under any circumstances, but particularly not in the United States Senate," Shelby said in a statement Thursday.

The data, released jointly with the Senate Appropriations Committee, is expected to increase pressure on senators to disclose their involvement in settlements and on employees to describe their complaints.

It became public hours after Sen. Al Franken (D-Minn.) delivered his farewell speech on the Senate floor. Franken plans to resign Jan. 2 amid allegations that he touched more than a half-dozen women inappropriately, most before he entered politics. He has apologized, denied some allegations and said he recalled other episodes differently. None of the allegations involved Senate employees.

Franken is one of seven members of Congress to resign or announce plans not to run for reelection after being accused of sexual harassment or misconduct since October. Some of these members — such as Rep. Blake Farenthold (R-Tex.) and former congressman John Conyers Jr. (D-Mich.) — reached settlements with former employees who said they were treated inappropriately.

Sen. Al Franken (D-Minn.) delivered his farewell address Thursday in the Senate. (Andrew Harnik/AP)

In total, workplace settlements involving member-led offices in the House and Senate have cost taxpayers at least $1.3 million between 1997 and this year, according to data released by the House and Senate Rules committees in the past month. At least $279,652 of that amount paid for settlements involving claims of harassment or sex discrimination, the data showed.

These figures paint an incomplete portrait of the cost of settlements on Capitol Hill. Although the Treasury fund pays for some agreements, many disputes are resolved before a formal complaint is filed, according to attorneys who have represented former House and Senate employees in workplace cases. Others are paid under the guise of severance.

The Rules Committee also released settlement data for Senate offices not led by members, such as the Office of the Sergeant at Arms. Those offices settled 10 complaints between 1997 and this year for $853,225, including three that involved allegations of sex discrimination or harassment.

Information about these agreements is scarce because virtually all of them are governed by strict confidentiality rules. In cases where details are known, it is often because the parties involved have found ways to confirm their existence and talk about the terms without breaching those rules.

There is no requirement that information about the settlements be public.

Debate over sexual harassment on Capitol Hill has centered on the process for filing complaints and seeking redress. Under the Congressional Accountability Act of 1995, employees with claims must undergo counseling and mediation through the Office of Compliance before filing lawsuits.

Some settlements are negotiated through this process and paid by a special account within the Treasury Department. This was the case with Farenthold, who settled with a former staffer for $84,000 in 2014. She said he made inappropriate comments designed to gauge whether she was interested in a sexual relationship.

Farenthold has denied this accusation but recently apologized for fostering an unprofessional workplace environment in his Washington office. He does not plan to seek reelection.

Other settlements are agreed to privately and paid as severance through members' office budgets. This was the case with Conyers, who paid a former employee more than $27,000 from his office funds after she accused him of harassment.

Conyers, denying multiple allegations he harassed and mistreated female employees, resigned his seat Dec. 5.

Neither method for settling complaints provides for transparency about how much money is being spent, the parties involved or the behavior alleged.

Since 1995, the special Treasury fund has paid more than $17 million for 264 settlements involving offices on Capitol Hill. The awards responded to a variety of workplace claims, including disability and age discrimination, and involved lawmakers' offices and other bodies, such as the Architect of the Capitol.

It had been unclear when the Senate's data would be released.

The Office of Compliance rejected a request by Sen. Tim Kaine (D-Va.) on Monday to hand over records of complaints and settlements that would not violate confidentiality agreements. It had sent settlement breakdowns from 1997 to 2017 to the Senate Rules Committee, however.