‘Catastrophic drainage’ damages beaver dam


“Concerns have focused primarily on the timing of the removal of the beaver dam and the amount of water drained, leaving early wetland breeders high and dry.”

BANFF – Beavers are nature’s ecological engineers, but they’ve long been persecuted for the damage they cause to human infrastructure.

So when Parks Canada diverted water from a beaver dam in the Cave and Basin Marsh Loop in early May to prevent flooding, environmentalists were quick to point out concerns, including for birds. during the sensitive spring nesting period.

Bow Valley naturalists say ‘catastrophic drainage’ has caused water levels to drop dramatically in an area of ​​Banff National Park designated for special protection, damaging the beaver dam and exposing the entrance to the lodge .

As a result, the beavers were seen piling mud on their dam.

“Water levels are reported to have dropped two to three feet in the marsh area,” said Reg Bunyan, former president of Bow Valley Naturalists.

“Concerns have focused primarily on the timing of the removal of the beaver dam and the amount of water drained, leaving early wetland breeders high and dry.”

This is around the same spot where the swamp was drained with disastrous results due to beaver activity in the 1980s.

The beavers returned to Sundance Pond near the Cave and Basin Wetlands about three or four years ago, creating two dams at the outlet of the Bow River.

Water levels have risen about 84 centimeters since 2021.

Due to beaver construction activities and rising water levels, Parks Canada is concerned about the risk of flooding of the Marsh Loop Trail, and potentially Banff’s commercial stables and recreation grounds. The trail is popular for hiking and bird watching, but is also used by Banff Trail Riders.

Parks Canada’s impact assessment review indicates that the Marsh Loop Trail will likely be impacted by spring runoff, resulting in potential trail damage and public safety closures if mitigation measures are not taken. not taken to lower water levels.

Additionally, the federal agency is concerned that water could break or flow over the levee causing flooding of the adjacent road, Banff Trail Riders stables and/or recreation grounds in the Town of Banff. “, according to the document.

“Water levels at Sundance Pond rose to above historic levels this spring, putting pressure on the levee at the start of the Marsh Pond Loop,” said Justin Brisbane, Parks Canada spokesperson for the park. Banff National in a news release.

Bunyan, who is a retired Parks Canada resource conservation officer, said the environmental assessment presented some well-reasoned arguments for lowering water levels, but said the declared threat of flooding to the facilities the city’s recreation was questionable.

He said the swamp is a Zone 1 Special Preservation Area for a reason, noting that it is a unique ecological area that is home to a number of rare species and offers some of the best opportunities for birdwatching in the Bow Valley.

While this designation does not preclude undertaking certain management actions such as altering water levels, Bunyan said it certainly calls for a precautionary approach such as smaller water adjustments and alterations. if needed.

“This is a special Zone 1 preservation and any management action taken there must be extremely conservative and taken with all appropriate ecological precautions,” he said.

On May 6, Parks Canada temporarily installed temporary Clemson levelers — simple, inexpensive devices made largely from PVC pipe — at existing beaver dams to reduce the risk of flooding in the area.

Levelers are designed to allow water to flow through a dam, while preventing beavers from quickly repairing dams. Beavers set dams based on sight, sound and feeling of running water.

“This is a proven and effective temporary solution to allow water to flow through the dams and restore water levels to their intended target,” Brisbane said.

“Consistent with best management practices for beaver dams, removal of keystone species was not considered an option.”

Beavers are considered a keystone species.

By building dams to block waterways to create ponds and wetlands, beavers provide many valuable ecosystem services, such as storing water during droughts and floods, creating habitats for many wildlife species and improved water quality.

BVN President Peter Duck said members are concerned about the damage being done to this special wildlife habitat at an obviously sensitive time of year and are unhappy at the loss of a special opportunity for visitors to view and to discover the natural processes of the landscape.

“It provided an opportunity to get closer to nature,” Duck said.

“You would think that would be the place where we could make a little sacrifice for the sake of the ecosystem.”

Beavers began to recolonize areas around Banff after more than 200 elk were trapped and relocated between 1999 and 2002 as part of Parks Canada’s elk management strategy to reduce elk attacks and restore the natural ecological process.

At the time, the large increase in the elk population around the townsite also resulted in widespread environmental damage, for example destroying aspens and willows, which are considered essential to the survival of songbirds and beavers.

“The beavers have been gone for a while, but they are back and doing what they would do; the willows have returned and the beavers are here to enjoy it,” Duck said.

The swampy area is also important for breeding birds at this time of year, with Duck noting that birds choose their nesting sites based on the characteristics of the habitat around them.

“Now someone has literally unplugged them and within hours it has changed, it’s no longer the site they thought they selected…so that’s probably a stressor for those species,” said he declared.

“There is a high probability that the birds have adopted their nesting behavior at this time of year, they now have to readapt and figure out how to reset or maybe they have lost a window.”

Bunyan said the decision to remove the beaver dam also highlights BVN’s ongoing concerns about the lack of a publicly available environmental assessment process at Parks Canada.

It took the Outlook five days to obtain a copy of the impact statement, which is a public document, through a media clearance process.

Bunyan said the assessment appears to have been written primarily from an aquatic/fisheries perspective, which is important, but had errors of omission from a breeding waterfowl perspective.

“Had this environmental assessment been released, the parks would have potentially had significant public comment on issues of nesting timing and water levels,” he said.

“No one wants or should need to review every routine Parks Canada decision. However, this is a beloved and highly sensitive area where hearing feedback and concerns from locals and birding experts would have been valuable to all.”

the Outlook contacted Parks Canada for an interview on Wednesday, May 11. The interview request was denied and a statement was received on the afternoon of Tuesday May 17th.

Brisbane said a development review, including options analysis and impact assessment, was carried out on the project which considered a number of valued ecological components including fish species, amphibians, migratory birds, the beaver dam itself, among others.

“As a result of the review, it was determined that adverse effects were not anticipated, and a balance of water and wetland management with permits for dynamic ecosystem processes to occur,” did he declare.


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