Swimmers won't have to rub the chlorine out of their eyes once they dive into a new swimming hole in north Minneapolis.

The Minneapolis Park and Recreation Board will soon demolish an old pool to make way for a pool-lake hybrid in Webber Park scheduled to open next summer. Instead of chlorine, wetland plants and a biological filter will purify the water -- the first pool of its kind in the country. Since no state guidelines cover such a facility, the Park Board needed the Legislature's permission to build it. Lawmakers approved it last month.

The pool is part of a $4 million renovation to Webber Park. Park Board officials said a natural treatment system worked within the park's existing landscape, which includes a wading pool and an artificial lake.

The new swimming hole will be connected to a wetland installed in the footprint of the adjacent pond, allowing water to move between them. The plants' roots will take in any nutrients and cleanse the water before pumping it back into the pool. The process should take 20 to 24 hours, said Cliff Swenson, the Park Board's director of design and project management.

Europe already has hundreds of swimming holes like this one. Jennifer Ringold, the Park Board's public engagement and citywide planning manager, said they have cleaner water than the city lakes.

The pool will add to the board's sustainability efforts by cutting down on the use of chemicals. It will also benefit the increasing number of people who are allergic to chemically treated water, Ringold said.

The pool should cost about the same as a regular pool in terms of maintenance, and may cost even less because it doesn't need chemical treatment, Ringold said.

With the natural treatment, the swimming hole won't qualify as sterile like a chlorinated pool, but Swenson said it will be safe.

"What we're really creating is that lake experience," Swenson said

Park officials also hope to use the pool for hockey and skating in the winter.

The board plans to start work on the pool by late winter or early spring in time to open next summer.

Masako Hirsch • 612-673-4263