A problem has bubbled up with the reinforcement moisture barriers intended to keep U.S. Bank Stadium dry, prompting a public oversight panel Thursday to spend $800,000 on a fix.

The repair payment — short of the $3.2 million sought by the stadium's general contractor, M.A. Mortenson Co., to address the ongoing water seepage — was an amount determined in mediation last week, Minnesota Sports Facilities Authority (MSFA) Chairman Michael Vekich said after a closed-door meeting and unanimous vote by the panel.

Vekich said that no new public money will be spent to repair the moisture barrier, "which will help ensure the stadium is maintained and protected for decades to come as Minnesota's largest public venue."

The $800,000 comes from a contingency fund created as part of a $21 million settlement last February with Golden Valley-based Mortenson and seven others over issues with the stadium's signature black zinc panels.

Last year's settlement required the contractors to replace 250,000 square feet of the zinc panels on the building's exterior because of moisture seepage in the underlying water barrier. The settlement included creation of a $1.7 million contingency fund from which the $800,000 comes, leaving a balance of $900,000 in the fund, Vekich said.

He added that the new agreement mitigates additional MSFA risk because it requires the contractors to cover any additional costs related to reinforcement of the moisture barriers.

Troubles with the stadium's zinc panels began before it opened in 2016, when panels came unfastened and flapped in the wind. Only after they were reinforced did it become clear a problem existed with the underlying moisture barrier.

Vekich said the stadium initially was designed to be "wet," with water weeping in and seeping out. The design fix, however, was to make the building "dry," keeping the moisture out entirely, he said.

The first phase of moisture barrier reinforcement and panel replacement was completed last fall largely on the western and northern facades of the building.

During that process, Vekich said, contractors managed to stop the bubbling, having "learned from the first application of how they clean it and clear it."

The next phase begins in February and is expected to be completed before the Vikings begin the 2021 season. As of Thursday, large swaths of zinc panels on the southeastern side of the building had been removed to test how the underlying blue barrier weathers the elements, Vekich said.

In a written statement, Mortenson officials said the MSFA action "helped address Mortenson's request for compensation" on the first phase of repairs.

"All remaining work will be carefully coordinated with future stadium events and is scheduled to be completed this year," the statement said.

Mortenson initially requested mediation over the panel problem in the fall of 2017. The $21 million agreement wasn't reached until February 2020. That settlement came out of closed-door talks with Mortenson, architect HKS Inc., M.G. McGrath Inc., Custom Drywall Inc., TRI-Construction, Larson Engineering Inc., Thornton Tomasetti Inc. and Studio Five Architects.

Since the COVID pandemic emerged in the United States last March, U.S. Bank Stadium has been shuttered to all but a few events.

The Vikings, the building's primary tenant, played the 2020 season there under strict state guidelines that barred paying fans. Most other events and concerts were postponed or canceled last year.

The $1.1 billion stadium was built from 2013 to 2016 with $348 million from the state and $150 million from Minneapolis. The Vikings paid the remainder.