Beavers can help protect waterways

Beaver dams can slow the flow of water and cool it for fish to spawn. Sediment can also reduce the speed of water during a flood.   |  Mary MacArthur photo

Natural water management | Studies show that ponds with beaver dams had more water during periods of drought

PRIDDIS, Alta. — The beaver may be immortalized on the five-cent piece, but for many landowners, the buck-toothed rodent is not worth a plugged nickel.

“Beavers often don’t have any more value than a rat in a granary,” said Reg Rempel.

However, he said, the animals actually do have value. Rempel helps manage the 4,800 acre Anne and Sandy Cross Conservation Area. He said beavers should be part of a holistic conservation plan on the former ranch south of Calgary.

The ecology groups Miistakis Institute, and Cows and Fish, collaborated to reintroduce beavers to the watershed in 2011.

The beavers were moved from the northern edge of Calgary and quickly established themselves.

Water quantity and quality have been monitored, but some fear that cougars may have wiped out the colony.

Many landowners have a love-hate relationship with beavers, but some scientists are say beavers can be used as natural water management specialists.

“Wherever habitat is suitable, beavers change the watershed,” said Lorne Fitch with Cows and Fish, the Alberta Riparian Habitat Management Society.

The change can be good when beaver dams and ponds increase groundwater, slow the flow of water and cool it for fish spawning, he said at a May 29 workshop in Priddis.

Sediment captured by beaver ponds broadens stream valleys with rich soil deposits over time. Up to 6,500 sq. metres or 382 tandem truckloads of sediment can be stored in each pond.

Beavers build ponds in a stair step style that can change the land gradients and reduce the speed of floods.

Researchers like Glynnis Hood of  the University of Alberta’s Augustana Campus in Camrose, Alta., have shown beaver work is beneficial during drought periods because the ponds and enhanced wetlands may be the only water sources and grass for livestock.

In her book, Beaver Manifesto, she said ponds with active beaver lodges had nine times more water during drought than ponds without dams.

The presence of beavers and their ponds recharges groundwater and preserves biodiversity.

Still, beavers can be a source of conflict between neighbours when one landowner wants them left alone and others want them gone.

“They have different perceptions in how they want beavers managed,” Hood said.

She is analyzing costs and benefits of beaver control, including damage repair and maintenance of beaver management projects.

She is also assessing community perceptions.

The research results are expected to be published later this year.

A case study at the Cooking Lake Blackfoot recreational area south of Elk Island in central Alberta looked at the costs of installing pond levelling devices over three years compared the costs of managing beavers in traditional manners, such as dam and colony removals.

Pond leveller pipes allow water to flow through a dam undetected by the beaver.

The pond levelling devices showed significant savings, she said.

While beavers can do a lot of good, there can be problems when their activities flood crops, roads, fences, block culverts and take out valuable trees.

“Living with them can be frustrating, it can be time consuming and it can be expensive,” said Fitch.

Managing them often requires a community decision.

Landowners can fence upstream culverts and wrap trees with wire net. Lodges and dams can be blown up, but beavers often return. Beaver deceivers or pond levellers reduce water levels and thwart the beaver’s ability to find the flow of water and plug it.

One of the most effective repellents seems to be a mixture of six cups of coarse sand and a gallon of latex paint. It is brushed on the tree trunks and the beavers leave them alone.

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