Alberta Health Services has issued a blue-green algae bloom advisory for Lac Ste. Anne, Alta., just days before the Pope is set to visit to kick off the community's annual pilgrimage — an event that is expected to attract thousands of people.
"We acknowledge that this lake is of high significance to many people, and we anticipate that it will be visited by large numbers of people next week as part of the Papal visit," AHS said in a news release issued Thursday.
"We are working closely with organizers of the visit to ensure that people can reduce their risk if they choose to visit the lake."
Visitors and residents in the area should avoid any contact with the blooms, and they should not swim or wade in any of the areas where the algae is visible, AHS says.
If someone comes into contact, they should wash themselves with tap water as soon as possible, AHS says.
The Lac Ste. Anne pilgrimage is set to resume in person from July 26 to 29. The annual pilgrimage had grown to about 40,000 people in 2019 — the last year it was held before shutting down for the COVID-19 pandemic.
This year's pilgrimage will start with an hour visit from Pope Francis.
Organizers say this year's pilgrimage will continue as planned, including the visit from the Pope.
"The health and safety of everyone attending the pilgrimage is a top priority. To that end, cleansing stations will be available at the Lac Ste Anne pilgrimage site," Andrew Ehrkamp, spokesperson for the Catholic Archdiocese of Edmonton, told CBC News in an email.
Naturally occurring algae can become visible in calm weather conditions, AHS says.
It can look like scum, grass clippings, fuzz or globs on the surface of the water. Its colour can range from hues of blue and green, to brown, or pinkish-red. It can smell musty or grassy.
Areas of Lac Ste. Anne in which the blue-green algae bloom isn't visible can still be used for recreational purposes, even while the blue-green algae advisory is in place, AHS says.
Lac Ste. Anne isn't the only lake currently under a blue-green algae advisory. There are also advisories in place for:
Half Moon Lake
Lac La Nonne
Lac La Biche Lake
Telegraph Park pond
Coming in contact with the algae can cause skin irritation, sore throats and eyes. If ingested, symptoms include fever, nausea, vomiting or diarrhea.