The naturally filtered pool at Webber Park in north Minneapolis partly reopened Tuesday after being closed for 13 days.

The deeper portion of the pool, including the lap area and diving dock, were opened but the shallow “upper pool” remained closed.

Since June 24, a “pool closed” sign had hung on the fence at 4330 Webber Parkway because of contaminated water, according to the Minneapolis Park and Recreation Department.

The pool is normally closed on Monday for testing and maintenance. Samples taken Monday and returned Tuesday allowed the partial reopening. Water samples were again taken Tuesday to see if the shallower portion can reopen Wednesday.

The three-year-old pool was the first in the nation to be cleaned by cycling water through an adjacent pond without chemicals. Most pools use chlorine to keep the water clean, and the natural process at Webber has proved to be less efficient. Heavy rainfall challenges the pool’s ecosystem. If a swimmer urinates, vomits or deposits fecal matter in the pool, the delicate balance is upset and the Webber Park pool must be closed.

When the pool is open, admission is free and it’s a popular draw for the neighborhood.

 

Correction: This is an update