Parks Canada announced that Miette Road in Jasper will remain closed for the time being pending delivery of a report.
Part of the road, starting 100 metres southeast of the entrance to Miette Campground, was washed out in late June.
"The road is unsafe to access due to a severe washout," Parks Canada wrote on its website.
The closure includes access to the Sulphur Skyline Trailhead.
"We recognize this situation impacts visitors travel plans," Parks Canada tweeted, "and is difficult for businesses and staff."
Parks Canada said an engineering firm is assessing the situation, with a final report delivered in early August that will include "short-term recommendations" over whether to allow safe vehicle access.
If the report recommends that part of the road can be used for single-lane alternating traffic, they pledged to allow it as soon as possible.