More water gauges needed, U of S flood report says

A review of how a major Saskatchewan dam handled flooding last year says changes are needed to prevent similar problems in future — including adding more water gauges.
Most of the hydrometric stations monitoring flows in the Saskatchewan River watershed are on the Alberta side of the border, the report says. (Water Survey of Canada)

A review of how a major Saskatchewan dam handled flooding last year says changes are needed to prevent similar problems in future — including adding more water gauges.

The 117-page University of Saskatchewan report released Tuesday was commissioned by the minister responsible for the Saskatchewan Watershed Authority in response to flooding that inundated some farmers' property downstream of the Gardiner Dam.

Inflows 'underestimated'

The report from the university's Centre for Hydrology said that the dam's minimum levels have been growing over the years and that means the potential for flooding is high if estimates of inflows are not accurate.

As it turned out, the report says, the estimates in 2011 were not good.

"Unfortunately, inflows were underpredicted in 2011 due to an underestimation of upstream snowpacks, inability to quantify ungauged inflows from prairie runoff, inadequate available information on upstream and local meteorological conditions, and reliance on statistical forecast procedures based on previous climate conditions," the report said.

The dam helped reduce the extent of flooding, but  for some farmers between Moon Lake and Saskatoon, the problem was how long their acres remained underwater.

Lake of water gauges noted

Part of the problem is a lack of hydrometric stations measuring outflows from the dam. A map provided with the report shows how water gauges in the Saskatchewan River watershed are distributed in Alberta and Saskatchewan — and it shows the vast majority are on the Alberta side.

"In the vicinity of Lake Diefenbaker there is a remarkable paucity of operating stations," the report says.

"The Saskatchewan portion of the Lake Diefenbaker watershed is almost entirely ungauged."

What's the priority?

The report also says the government needs to figure out what's the priority at Gardiner Dam — flood protection or electricty generation and water supply.

"If downstream flood protection is one of the primary goals for the reservoir, then the winter minimum level of Lake Diefenbaker should be reduced until improvements in forecast capability are realized," the report said.

On the other hand, if water supply and hydroelectricity are the biggest goals, then the public should be told there is more likely to be flooding, so they're not surprised, it said.

The report said the flooding wasn't the fault of Saskatchewan Watershed Authority staff, whom they said did a "superb job" given the tools that were available to them.