BONNYVILLE – The public has learned almost all there is to know about the Moose Lake weir and its impact on water levels, which according to experts is nearly none.
The weir, which is owned by Alberta Environment and Parks but is being removed by Alberta Transportation, has been a thorn in residents’ sides for years, especially after high water levels in 2017 caused damage to properties along the shoreline.
The province hosted a Moose Lake Weir live information session on Thursday May 27, with a second scheduled for Wednesday.
In addition to provincial representation, panelists from Wood, Environment, and Infrastructure, the company hired by Alberta Transportation as consultants to complete the engineering, design, environmental work, and construction management of the naturalization project.
Lucy Chen, water resources engineer with Wood, Environment, and Infrastructure, explained to the 23 people who attended the virtual information session why the weir is being removed and the history of the structure.
Background
The weir, which is located on Moose Lake River roughly seven kilometres downstream from the outlet of the lake itself, was built as a way of “promoting the water supply for the Town of Bonnyville and help stabilize the Moose Lake water levels for recreational use,” Chen explained.
Now, the town has an alternative water supply and the weir is doing very little to maintain the water levels of the lake.
Chen detailed how the weir, built in 1951, has an upper and lower crest section, and how in 1985 a debris boom was installed. The weir also features a fish structure in order to “promote fish passage of the structure.”
The study
“A relatively wet year in 2017 resulted in one of the highest reported lake levels and caused flooding of development and infrastructure around Moose Lake. The flooding resulted in questions from stakeholders about the potential Moose Lake management options and led to a study concluded by Wood in 2018,” said Chen.
The study determined removing the weir wouldn’t have a significant impact on water levels for scenarios of typical, low, and high flows.
It also discovered that during both dry and wet periods, the weir water level didn’t match the lake water level, which according to Chen “indicates the weir is not a significant influence on lake levels.”
“If the weir is controlling lake levels, then generally the water levels should match... However, as shown, during dry and wet periods the water levels do not match. This indicates the weir is not significantly influencing lake levels,” she continued.
The study found natural factors such as reed beds and beaver dams are a common occurrence on the river, and are believed to have a significant influence on the Moose Lake water levels.
“The 2018 study assessed the impacts to lake water levels with and without the weir in place, the study showed that the removal of the weir didn’t significantly affect the Moose Lake water levels,” expressed Chen. “Natural factors... act as a barrier along Moose Lake River.”
Naturalization Project
In 2020, Wood initiated the environment and engineering studies on the naturalization of the Moose Lake weir.
“The proposed construction timeline is in the fall of 2021 into the spring of 2022, during a period when the water levels of the Moose Lake River are low,” Chen explained.
Post construction monitoring will be taking place in 2022 to 2023 to “ensure the naturalization was correctly implemented,” Chen added.
Liv Hundal, project manager for Woods, Environment, and Infrastructure, explained the work they plan on doing after the weir is removed in order to return the area to its natural state.
“The project objective is to remove the existing concrete weir and naturalize the Moose Lake River,” he detailed.
Once the artificial concrete weir is removed, their objectives, Hundal said, are to improve fish passage and navigability, revegetate with native vegetation and vegetate any of the disturbed areas adjacent to the structure, and ensure and promote a long-term stability of the river and surrounding areas.
After their work is done, they will continue to monitor the area to help them understand how the site has naturalized.
In order to get approved
Due to the nature and location of the weir, a number of government bodies and other approval processes were needed before moving forward.
This includes the Water Act, Migratory Birds Convention Act, Wildlife Act, Fisheries Act, Indigenous Peoples’ Consultation, Canadian Navigable Waters Act, Public Lands Act, and Historical Resources Act.
“It’s a comprehensive process, it includes both provincial and federal legislation and policies,” Hundal expressed.
Questions from the public
One resident wanted to know why they were bothering to remove the weir at all if it isn’t impacting water levels, to which Liz Smith from Alberta Transportation specifically relating to the project component for the weir answered it comes down to cost and maintenance.
“Although the weir isn’t affecting lake levels, it has resulted in Alberta Environment and Parks to undertake extensive management of the site in attempts to manage water levels so operations and maintenance of the structure over the years. (Removal of the weir) is seen as a first step in alleviating any concerns with water levels along the Moose Lake River and the lake as well,” she explained.
Carlin Soehn, Alberta Environment and Parks operation of infrastructure manager responsible for the Moose Lake weir, noted while a weir seems like a structure that can be placed there and left, it does require ongoing maintenance, inspections, and funding.
"When a structure isn’t meeting its objectives or its original intent, those are some of the things we do consider when looking at it,” he said.
Kellie Nichiporik was curious why the province was allocating dollars to remove the weir, but wasn’t planning on addressing the reed beds and beaver dams.
“In terms of spending money on reed beds and beaver dams, that’s certainly not an Alberta Transportation mandate, and they’re not in the jurisdiction of Alberta Environment, so removing this weir is the first step in making beaver management affective for this site,” detailed Smith.
Hundal added, “There are lots of consequences associated as well with long-term maintenance and management if you get into reed bed management and beaver dam removal. It’s something that would require active management on an annual basis for however long you do it. There are environmental implications to that as well, there are ecological benefits from beaver dams and from the reed beds as well.”
With this in mind, if it were to be done, the province would have to consider the negative environmental impacts associated with it, such as how it would affect the lake levels.
“If it ended up lowering lake levels, that has some impacts as well, which aren’t entirely beneficial,” said Hundal.
Asking about the budget of the project was Chuck Dechene, who was told by Smith at this point the work is being tendered so “we’re not talking about the budget or what we think it will cost today, but one it is tendered and awarded the contract cost then becomes public.”
Whether or not the project was a political whim had Rob and Louise Fox curious.
“This is a capital project that was identified and is being delivered but it certainly isn't a political project for anyone,” stressed Smith.
Other questions surrounded how removing the weir would impact fish, water levels, and overall flow of the river.
“It’s important to keep in mind that it’s the inflow that has the really big impacts. These lake level fluctuations are primarily influenced by these climate influences. It’s the snow pack, rainfall, and evaporation, and the streamflow into the lake that are the primary drivers of the lake levels,” expressed Hundal. “It’s important to keep that in mind and not get too focused on the Moose Lake River itself.”
Soehn added, “You could have a perfectly good channel and you would still get flooding and drought conditions because of those factors.”
Another virtual information session is scheduled for Wednesday, June 2 starting at 6:30. Residents can register beforehand on Alberta.ca by searching Moose Lake weir.
