Waterton Lakes National Park in southern Alberta temporarily shut its gates for the first time ever on Sunday and visitors were being turned away at the entrance by Parks Canada staff.

The park has since reopened, but could shut again if traffic levels rise.

"We will limit traffic access into the park where and when needed this season to provide the safest possible experience for our visitors, wildlife and staff," said Parks Canada in a news release.

"We are monitoring and reviewing this process and will make adjustments as necessary."

High volumes

Earlier in the day, Locke Marshall, the visitor experience manager for the park, said the park was at capacity and staff was out at the intersection of Highway 5 and Highway 6, diverting traffic.

Marshall said they're not actually sure what the maximum number of visitors is, per se, but the park has traffic modelling and monitoring that alerted them to the fact the park was at capacity.

"It's telling us that parking is pretty much at maximum and traffic is still moving slowly, but it's still moving and that's what we're trying to maintain for public safety at this time," he said.

Marshall said about 2,000 vehicles had entered the park in the hours leading up to the closure and today is the climax of crowds helped by free park passes made available for Canada's 150th birthday.

"This has been a very busy year. Overall, the traffic's been around 19 or 20 per cent higher for the whole year, but today we're tracking at probably closer to 30 per cent higher than our busiest day ever, so it's a pretty busy day today," he said.

Could close again

Those turned away from the park were not permitted to stop and wait on the highway and were given information on other activities and areas in southern Alberta that are similar to Waterton.

The closure lasted for about an hour before it was determined more traffic could access the park.

Marshall advises those wanting to visit to check the Waterton website or monitor the park's social media channels.