The Science Museum of Minnesota, one of the region's premier education centers and tourist attractions, is plagued by water damage that will require about $26 million in repairs — half of which could fall on state taxpayers.

Museum leaders believe the problem is a result of a major design flaw and sought legal action against the architecture firm that in 1999 designed the museum, nestled in the downtown St. Paul bluffs overlooking the Mississippi River. But since the scope of the water problems wasn't clear until an independent engineering study in 2012, a judge recently ruled that the 10-year statute of limitations in seeking damages had expired.

Mike Day, senior vice president at the museum, said Thursday there is no present danger to guests, and the damage does not affect exhibits.

"The structure has complete integrity, the air quality is good," Day said. "There's an urgency to this that we are acting upon so it does not become an emergency."

Since opening 15 years ago, the museum's maintenance crews have plugged smaller leaks at the 370,000-square-foot building. But it wasn't until 2012 that major deficiencies were revealed, such as a missing vapor barrier under the metal panel walls of the popular Omnitheater, which built up condensation and prematurely aged the structure.

In 2014, the museum was forced to interrupt operations for the first time by closing the Omnitheater for eight days after a harsh winter caused a leak in the lobby wall, Day said. For now, short-term repairs will be made to replace insulation and seal windows until funding becomes available for larger fixes. Quarterly air quality tests also are being performed.

Major renovations will encompass redoing almost the complete exterior, which will be a multiyear project.

"It's an expense that includes not only building anew, but deconstructing the old," said Day, adding that the exterior of the Omnitheater is a priority.

Day believes the museum has support from Minnesota legislators who have previously called it a "state asset." Leaders have submitted a 2016 bonding bill request, which would require the museum to raise half — about $13 million — of the funding.

The museum's facility reserve fund will cover about one-quarter of the cost, Day said. It also has borrowing capacity through its bank.

Admission will not be raised to help cover repairs, Day said, and daily operations will not be affected once larger renovations begin.

The Science Museum draws more than 1 million visitors a year and houses the only convertible-dome Omnitheater in the nation. "Space: An Out-of-Gravity Experience," on exhibit through Sept. 7, is the most complex and expensive show in the museum's history.

The Associated Press contributed to this report.

Liz Sawyer • 612-673-4648