The Webber pool in north Minneapolis will remain closed this weekend.

The three-year-old, $7 million pool, which uses natural filtering to clean the water rather than chlorine, won’t reopen until Tuesday at the earliest.

It has not been fully open since June 24 because of water contaminants. It had reopened for a brief period before being shut down again earlier this week. On Tuesday, Park Board staff blamed ducks for the water problems, saying they are swimming and depositing fecal matter in the holding pond during the day and in the swimming pools by night, a contamination that compromises the natural filtration system.

If the pool does reopen Tuesday, it will have lost 20 days of use. Last year, it was closed only six days during the whole season.

Announcing the weekend closure, park staff said that although the enterococci bacteria numbers are decreasing, they are not at the level needed to reopen the pool. New samples will be taken on Monday, when the pool is typically closed.

Staffers have already installed swan and alligator decoys, mobile bird deterrents and streamers across the regeneration basin, the Park Board said.

Jeremy Barrick, assistant superintendent for environmental stewardship, said the board plans to buy three floating fountains, as well as coyote decoys and urine to be applied on the perimeter of the pool. The total cost of the new deterrents is estimated to be less than $8,000.

The Webber pool was the first of its kind in the nation to be cleaned by cycling water through an adjacent pond. Its 500,000 gallons of water are circulated between the pool and the pond, which has some 7,000 aquatic plants rooted in limestone and granite gravel, according to the Park Board’s website.