Ocean beach closures due to high bacteria a sign of things to come, says prof

High bacteria levels have closed two ocean beaches in southwest Nova Scotia for the first time ever, a problem that's only expected to get worse as the hot weather persists.

Unusual event 'reflective of the flickering switch of climate change that we're experiencing now'

Port Maitland Beach in Yarmouth County is one of two ocean beaches that are closed to swimmers due to poor water quality. (Province of Nova Scotia )

High bacteria levels have closed two ocean beaches in southwest Nova Scotia for the first time ever, a problem that's only expected to get worse as hot weather persists.

Recent testing at Port Maitland Beach in Yarmouth County and Mavillette Beach in Digby County revealed higher than normal levels of enterococci, which are bacteria found in mammal fecal matter. Both beaches are closed to swimmers until testing shows the water is safe.

Queensland Beach, about 45 minutes south of Halifax, was closed to swimming last month for the same reason.

While bacteria is more often a concern at freshwater beaches, the heat, humidity and low wind this summer means ocean beaches aren't immune, said Bruce Hatcher, chair in marine ecosystem research at Cape Breton University. 

"This is a very unusual event and it's reflective of the flickering switch of climate change that we're experiencing now," said Hatcher. "We know that [this weather is] going to get more and more frequent as we move into the depths of the climate change, so like get used to it."

Bacteria levels 'quite high'

The Nova Scotia Lifeguard Service has been testing water quality at 23 beaches, including many provincial parks, since 2010.

If their tests show enterococci levels above 70 colonies per 100 millimetres of water the province closes the beach to swimming. Director Paul D'Eon said readings at the two beaches were "significantly higher than the 70."

"There were some that the lab shows is above 250 so the samples were quite high at both sites and it was really quite an easy decision that the beaches should be closed," D'Eon told CBC's Information Morning.

Enterococci can cause gastrointestinal problems such as diarrhea and vomiting if they are ingested or get into the body through an open wound. Children, seniors and people with health issues are most at risk.

Nova Scotia Life Saving Society president Paul D'Eon says tests follow the Guidelines for Canadian Recreational Water Quality's recommended thresholds. (Rachel Ward/CBC)

D'Eon said signs have been put up at the two beaches, and lifeguards are still on duty to advise people not to swim. 

He said this summer's high heat and humidity essentially means the surface water has become "a petri dish that would breed bacteria."

Too much heat, not enough wind

Enterococci can end up in ocean surface water from sewer pipes and runoff from nearby farms. 

Tides and winds usually mix that surface water around so it's diluted with colder, salty water. This mixing ensures there's no risk to people's health, said Hatcher, but it hasn't been happening this summer.

He said ocean beach closures are likely to increase, although not necessarily steadily year to year.

"But let's be clear. These kinds of events are going to happen more frequently," he said.

Queensland Beach was closed to swimmers in mid-July. (Anjuli Patil/CBC)

Hatcher said beachgoers should be careful not to ingest the water. If people are worried about bacteria, he said it's a good idea to choose beaches that are far away from towns, farms and other human activity.

It's also a good idea to talk with locals about the beaches, he said.

On Friday afternoon, Halifax Regional Municipality announced that Government Wharf Beach in Musquodoboit Harbour has been closed for swimming due to high bacteria levels in the water. It is an unsupervised beach.

Read more articles at CBC Nova Scotia

With files from CBC's Information Morning