TORONTO -- Canadians looking to take the plunge in safe, clean waters this long weekend can use an app to scour beaches across the country with the best and worst water quality.

The Waterkeeper Swim Guide app monitors the water quality of more than 7,000 beaches across North America, the Baja Peninsula and New Zealand, all aggregated from data contributed by local waterkeepers.

Krystyn Tully, co-founder of the app that was launched by the Lake Ontario Waterkeeper in 2011, said the August long weekend is always the busiest time of year for the app's use.

"It's the hottest, people are planning their trips, most people have vacation time," she said. "We realized just how important beaches are to Canadians and what a huge interest there is -- and demand -- for better water quality information."

App users can browse the beaches nearest to them on a map for the ones safe to swim in, and can check the beaches' histories of bacteria-testing to confirm how consistent the water quality levels have been.

Across the country, the guide recommends popular beaches with consistent water quality that include Gordon Bay Provincial Park on Vancouver Island; Wizard Lake Jubilee Beach near Edmonton; Sifton Beach on Dauphin Lake in Manitoba; Parc Jean-Drapeau Park in Montreal; and Campbell Point Beach near Halifax.

In Ontario, the guide has pinpointed spots such as Kingston's Big Sandy Bay, Long Sault's Plage Mille Roches Beach, Guelph Lake, Pinery Provincial Park and Wollaston Lake Beach for their consistently clean water quality.

But Thunder Bay's Sunnyside Boulevard Beach, Windsor-Essex's West Belle River Beach, Hamilton's Bayfront Beach and Carleton Place's Riverside Park Beach and Centennial Park Beach have had the most consistently poor water quality in the province, the guide found.

Local waterkeepers typically monitor beaches daily for quality indicators such as phosphorus and E. coli levels, both of which, in excess, can result in blue-green algae -- a toxic bacteria that can kill fish and sicken swimmers.

Users can also report pollution, litter or other unsafe conditions at the beaches through the app and website. Tully said after Toronto's rainy June, when excess stormwater flowed into Lake Ontario, many users began using the app to report hypodermic needles washing ashore on the beaches.

But most commonly, she said, the app's primary users are couples in their 30s with young children looking for beaches where they can safely take family trips.

"Usually the feedback that we get is a mix of people just thanking us for making it easier for them," Tully said.

The Waterkeeper Swim Guide is available on the Apple App Store, Google Play or its website.