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Lesser Slave weir modification being discussed
Joe McWilliams
Lakeside Leader
A report on the management of water levels in Lesser Slave Lake and the river that drains it is inching its way along. M.D. #124 council heard about it at its Nov. 26 meeting.
One of the more interesting tidbits from the presentation had to do with enhancing the ability to control the outflow from the lake. Of three options on the table, the one the Lesser Slave Lake Watershed Council seems to favour involves culverts with gates that could be opened when more river flow is required. The other options were the siphons over the weir when flow is too low (which have been used twice already), and a modification of the weir.
Making the presentation were Rod Burr of Alberta Environment (on behalf of the watershed council) and watershed council executive director Meghan Payne. Burr said Alberta Environment appears not to like the siphon option, although he didn’t say why. The modification of the weir might involve punching a hole through it that could presumably be opened and closed when needed. Burr said, or implied, that such an option would be pretty expensive.
The installation of three gated bypass culverts doesn’t sound cheap either. And according to Burr, Alberta Environment doesn’t have all that much cash lying around.
“Typically our department only gets four million capital dollars a year,” he said, adding that of that, the northern region only gets around $250,000, “and that’s committed for the next five years.”
The need for some sort of device to increase flows over the weir became evident in 1999 when a combination of low lake levels and east winds virtually stopped the river from flowing over the weir. This put downstream industrial and municipal users in jeopardy, not to mention the aquatic life in the river. The M.D. responded to the crisis by inserting six or seven large siphons over the weir, which served to increase the flow to the six cubic metre per second minimum set (somewhat arbitrarily, Burr admitted) by the province.
There are other issues affecting river flows, principally the periodic silting upstream where the river leaves the lake. Burr was asked about the issue.
“I think you’re going to have to dredge,” he said.
Therein lies a problem. The M.D. got in trouble with federal government agencies for dredging (or perhaps for the way it was done) in late 2006, when ice and silt blocked the outflow from the lake. The M.D. has made it plain that it wants Alberta Environment to make the decisions (and take the heat) should the need to dredge arise again. They heard that the watershed council has written the minister to that effect, but that the matter remains in limbo.
“We just never want to be in that position again where the legal onus is on us,” said reeve Denny Garratt.
Commenting on the draft water management plan report, councillor Darcie Acton said she was surprised to see that in spite of the watershed council’s representations to Alberta Environment, the report “still has language that puts the M.D. in the lead position (regarding the decision to dredge).”
The management plan has some way to go before Alberta Environment adopts it. Just how long that might take remains unclear, but Burr did say a public engagement process has yet to be undertaken.
Meanwhile, council heard that the lake is dropping and there is the potential this winter for another water flow crisis in the river. Solving it would not be a simple matter.
“I don’t know if you’re aware,” Snider said, “but we have no more siphons. Their day is done. We could have a problem.”
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