Update on flood mitigation

One year after the deluge there’s still work to be done

Calgary and communities affected by the 2013 floods are better able to weather large-scale flooding now than they were a year ago but the most important mitigation projects are still on the drawing board.

On April 29 the province hosted its second all-day flood symposium in Calgary to offer status reports on flood mitigation efforts throughout Alberta. The first symposium was held October 4 2013.

During the event Matt Machielse assistant deputy minister of Environment and Sustainable Resource Development (ESRD) discussed large-scale mitigation plans the provincial government is still assessing including major projects intended to protect Calgary. They include: a proposed dry dam at the confluence of McLean Creek and the Elbow River; a storage pond in Springbank that could hold excess water diverted from the Elbow River overflow; and an underground tunnel meant to divert water from the Glenmore Reservoir to the Bow River during a flood. The projects are estimated to cost roughly $200 million each.

While city administration’s feasibility study of the potential benefits of the diversion tunnel isn’t due until June ESRD Minister Robin Campbell says independent consultants have recommended the other two go ahead and the government supports putting them in place as soon as possible. Campbell says he considers building the McLean Creek dam an especially high priority. The Treasury Board recently approved $600 million to fund flood management plans over the next three years.

However Campbell says construction won’t begin any time soon because final approval for each project requires extensive environmental impact assessments; stakeholder engagement; private land acquisition; compliance with municipal provincial and federal regulations; and negotiations with affected federal departments such as Environment Canada Fisheries and Oceans and Indian Affairs.

Campbell also points out waterway management is complicated because the government must calculate the downstream effects of altering upstream flow “before we can divert drop one.”

For example he says “when we started developing diversion [plans] on the Highwood River to protect High River we realized very quickly that downstream of that we have the Bassano dam that we almost lost in the last event — a 100-year-old dam that we desperately need to provide irrigation water and water to communities in all of central south Alberta…. We have to have capacity so that we can hold water back so everything doesn’t flood downstream.”

Meanwhile officials says they know that with the spring melt approaching Albertans are becoming concerned over whether we will be prepared in time for the next flood.

“A lot of us are anxious. I’m anxious. And I know many people in the room are anxious about thinking about what may happen to us going forward” admitted Calgary Mayor Naheed Nenshi to symposium attendants.

“I know people get impatient with the fact that it’s been almost a year considering where we’re at in some of the mitigation projects” says Campbell. “I know that Albertans are very frustrated. It’s our intention to move forward as quickly as we can… but understand this is a very complicated process.

“We had hundreds of options and everyone has an opinion on what the right option was to move forward…. For us to say that there are plans in place and we’re moving forward and we’re going to have a date we just can’t say that right now because we need to let the stakeholders have a say” Campbell added.

Among those hundreds of options for tackling future floods were numerous dams on the Bow Red Deer Highwood and Sheep rivers. Machielse says all but the McLean Creek dam were deemed too expensive environmentally devastating or geotechnically difficult to justify their construction. The city’s expert management panel on river flood mitigation also decided that dredging rivers or the reservoir would be equally impractical and unlikely to reduce flooding.

That doesn’t mean Alberta and Calgary have done nothing. The province has approved and started work on more than 100 erosion control projects involving stabilizing river banks and building berms and dykes in southern Alberta and Fort McMurray (which experienced significant flooding in May 2013).

Of the 90 sites determined to need riverbank erosion control measures within Calgary construction on 42 sites deemed critical is currently underway. All are due to be completed before the end of May. To date city administration has identified nearly 150 other flood-related infrastructure projects requiring repairs or restoration work. Crews have already cleaned 40 kilometres of storm mains inspected 84 storm water outfalls and removed 50 tonnes of debris from the Bow and Elbow rivers.