WINNIPEG -- A report commissioned by the Manitoba government says it could cost up to $40 million to repair and rebuild provincial parks devastated by spring floods in 2011.

The report, delivered to the government last year and recently obtained by The Canadian Press, details the damage caused by the flooding -- one provincial park stood under water for four months -- and sets out three options to rebuild with price tags ranging from $17 million to almost $40 million.

"Some buildings in parks that experienced higher flood levels and longer flood periods had significant mould issues," says the report prepared by engineering company AECOM.

"In any case, where mould is significant the buildings were recommended to be demolished/reconstructed. This approach was strongly reinforced by related studies where assessment teams noted in May 2012 that mould in flooded buildings had increased substantially beyond levels observed in the late fall of 2011.

"Mould poses substantial health and safety concerns."

Manitoba experienced one of the worst and longest floods in its history in the spring of 2011. Officials operated the Portage Diversion, a channel that funnels water from the Assiniboine River into Lake Manitoba, over its designed capacity. That pushed water levels up on Lake Manitoba and Lake Winnipeg, cut off roads and damaged homes and cottages.

Provincial parks on the water's edge were hit hard. The report says campsites and parking lots were buried in sand and silt. At some parks, floodwater rose as high as washroom ceilings and park buildings.

In St. Ambrose park, on the shores of Lake Manitoba, the water ate away at land and buried much of what remained under a metre of sand. Spruce Woods park on the Assiniboine River southwest of Winnipeg was under water for four months and still hasn't reopened completely.

Damage at the Spruce Woods campground occurred partly because, once the swollen river breached a dike, floodwater pooled inside until the dike was breached again, allowing the water to escape.

The cheapest repair option the report recommends is simple cleanup and replacement of mouldy buildings. The most expensive option involves a rebuild of the parks to meet the highest environmental standards, replacement of damaged buildings and new flood protection measures.

"Manitoba's parks have never been so devastated by a weather event, at least recently," Conservation Minister Gord Mackintosh said. "There certainly were some surprises and lessons learned."

Mackintosh said he expects the province will spend about $22 million to clean up the parks and beef up flood protection.

Eight of the 10 parks have already been cleaned up, but Spruce Woods may take another seven years, he said.

The majority of the $22 million budgeted is to be spent there, Mackintosh indicated. The park is to have better flood protection, including concrete toilets which can withstand virtually anything.

"Even if a flood moved it feet or even miles (away), I understand the washroom can still be intact and can just be moved back into place."

The parks are being missed by nature lovers.

Eric Reder with Manitoba's Wilderness Committee suggested floods that were once rare are becoming more commonplace because of climate change. Protecting such pockets of wilderness are vital, he said.

"Connecting to nature, connecting to wilderness and finding solace in being outside is a really important part of the human experience," Reder said.

"The more that they can do to get parks that are closely accessible to people, get those parks back up and running, that will be a long-term benefit for us."