Following decades of lobbying for a provincial park in the Castle wilderness area, the province’s NDP government will Friday make good on its campaign pledge to better protect the iconic area in southern Alberta.

Sources say Environment and Parks Minister Shannon Phillips will announce plans to change the boundaries of the protected area, both expanding the existing wildland park and creating a new provincial park in southern Alberta.

They will cover 1,040-square-kilometers.

The park designations would effectively ban timber harvesting throughout the area and keep off-road vehicle use to marked trails. It would also allow the government to create new provincial campgrounds.

Phillip’s announcement, which will take place Friday morning in Blairmore, comes less than a month after several conservation groups started a letter-writing campaign to remind the NDP government about its pledge to better protect the Castle wilderness area.

The party’s election platform said it would protect the area, but it didn’t say how. Since they came to power, the New Democrats have suggested they would enhance the area’s current park protections.

One of the Herald’s sources said the government will have to amend the South Saskatchewan Regional Plan after Friday’s announcement.

The land-use plan, released in August 2014, committed to a 546-kilometre conservation area known as the Castle Wildland Provincial Park. It’s being managed as a park under the plan but has never been formally designated by the province as a protected area.

Changing the boundaries will have implications for the forestry industry, particularly Spray Lake Sawmills, which holds the timber harvesting licence for the area. It has previously said it would have to be compensated for the licence should the government change the boundaries.

Several conservation groups, however, have been lobbying the province for decades to protect 1,020-square kilometres as a provincial park.

Although many of the groups knew about Friday’s announcement, no one would discuss the specifics.

“We’re definitely hoping it’s a positive announcement for the protection of the Castle, but that’s all I know,” said Katie Morrison, conservation director with the southern Alberta chapter of the Canadian Parks and Wilderness Society.

Others would only say they would be at Friday’s “big” announcement in Blairmore.

The Castle wilderness area provides about one-third of the water for the Oldman basin, the source of drinking water for downstream communities such as Lethbridge.

Its waterways are also home to Alberta’s provincial fish, the bull trout, while the land is critical habitat for grizzly bears and other wildlife.