The province is proceeding with preliminary design of water diversion and storage projects to protect vulnerable communities along the Highwood and Elbow Rivers from floods as devastating as those experienced last summer.

But Environment Minister Robin Campbell cannot predict when or if the estimated $580 million in investments will proceed.

“I know that people get impatient that we’re up to almost a year and we’re still considering where we’re at on some of the mitigation projects,” Campbell told reporters at Tuesday’s flood symposium in Calgary.

“It’s one thing to have engineers come and put a plan together and say we’re ready to go, but understand that especially when you’re dealing with water and rivers and flowing water, there’s environmental impacts and assessments that have to happen.”

While a route has not yet been decided, the province will conduct environmental screening and community consultation of a diversion canal around flood-ravaged High River that could handle roughly one-third of the flow that hit the southern Alberta town last June.

The seven-kilometre-long floodway would be up to 200 metres wide at some points and would cost an estimated $200 million to build.

Many of the dry dams on the Elbow River upstream of Calgary proposed by a citizen’s advisory panel last fall have been dismissed because of their environmental or financial cost, but provincial consultants have found two projects they believe may be worth considering.

One is a 50-metre-high structure that would be built southwest of Bragg Creek that would have a storage capacity of 49 million cubic metres, and the other is an off-stream reservoir near Springbank Road west of Calgary that would hold 59 million cubic metres.

Combined, they would hold roughly four times the water of an an emptied Glenmore reservoir. Enough, say engineers, to handle the peak flows the river experienced last June and leave adjacent communities relatively unscathed, and to also store water when drought threatens.

Each is estimated to cost approximately $190 million to build, including the cost of land acquisition.

“We’re going to have to sit down with private landholders and talk about compensation, and that could take some time.” Campbell said.

“It’s our intention to move forward as quickly as we can, as efficiently as we can and as cost effectively as we can, but understand this is a very complicated process.”

All the projects will have to be screened for compliance with provincial water legislation and federal fisheries regulations.

The province has allocated $150 million over the next two years, during which time the projects will be designed, environmental assessments done and community consultations held.

The fate of a proposed tunnel in Calgary that would divert some of the Elbow River’s flow under 58th Avenue from the Glenmore Reservoir to the Bow River remains unknown.

But Wolf Keller, head of the city’s expert panel on flood mitigation, said the project — with a rough price tag of $290 million — is still being considered.

“The cost of them (storage dams) is in the ballpark of the tunnel, so if you have an option among three different cars and you only need two, well, you look at all the cars and see what might be best for you,” Keller said.

While the off-stream reservoir is a new idea, the dry dam near McLean Creek was originally proposed in a 1986 provincial study as a means of mitigating flooding along the Elbow River in Calgary.