The metro’s most popular manufactured swim beach is headed for an overhaul, delaying its traditional May opening.

Washington County commissioners on Tuesday approved a plan to reconstruct the 29-year-old pond at Lake Elmo Park Reserve to replace a decaying liner and underground pipes that circulate chlorinated water.

The work would include reducing the pond’s maximum depth from 6 feet to 4 feet to lessen the potential for drownings, said County Engineer Wayne Sandberg.

“We think most people won’t even notice the difference, but the lifeguards will, and that’s important to us,” he told commissioners.

The swim pond has emerged as one of Washington County’s greatest assets — but also one of its enduring costs. Tens of thousands of people use it each summer, straining services. County leaders have acknowledged that picnic areas, parking lots and restrooms are inadequate, and those shortcomings will be addressed later.

Next spring’s work will rejuvenate an elderly pond to make the water clearer and safer. “Overall the system is very old, it’s inefficient, and we think we can do a better job with it,” Sandberg said.

Construction is to start in March and be done in early June, meaning it won’t be open to the public over the Memorial Day weekend. But Commissioner Ted Bearth said the work is overdue. “We’ve been extremely lucky that we haven’t had to jump into the middle of summer to fix something,” he said.

The Lake Elmo beach draws about 10 times the number of people who visit the beach at another big county park, Big Marine. The crowd in the Lake Elmo park grows large enough on summer weekends that children sometimes go missing, and that leads to water searches, Sandberg said.

A shallower pond would be safer and would better meet the needs of most pond-goers, many of whom prefer splashing in the water over swimming, he said.

Once the pond is reconstructed, the county will consider improvements to the concession stand, lifeguard station and surrounding sidewalks. Picnic areas and parking lots also need updates; they were designed years ago, when far fewer people came to the pond.

Tuesday’s action approved a contract for $149,300 to Barr Engineering for design and construction. The total cost of the retrofit was estimated about $1 million, funded with Met Council grants.