Beavers could hold the key to saving our water

By Mark Waghorn via SWNS

The humble beaver could hold the key to saving our water, according to new research.

Beavers dam building skills protect rivers threatened by climate change, scientists say.

The buck-toothed aquatic rodent creates ponds and excavates waterways when its habitat dries up.

It will help lessen the damage by controlling the flow and improving the quality of water.

"As we're getting drier and warmer in the mountain watersheds in the American West, that should lead to water quality degradation," said senior author Professor Scott Fendorf, of Stanford University.

"Yet unbeknownst to us prior to this study, the outsized influence of beaver activity on water quality is a positive counter to climate change."

The incredible creatures have been dubbed the "working class heroes of their ecosystems."

They cut and collect wood, block creeks, streams and rivers and construct architecturally elaborate lodges.

It is an industrious instinct that stretches back millions of years. Their handiwork is responsible for the lush, fertile land they love.

The findings in Nature Communications are based on mountain rivers in Colorado. It found the animals' wooden barriers raise water levels upstream.

Water is diverted into surrounding soils and secondary waterways - known collectively as riparian zones.

They act like filters, straining out excess nutrients and contaminants before water re-enters the main channel downstream.

The benefits is set to grow in the years ahead. Hotter, arid conditions will lessen water quality.

These same conditions have also contributed to a resurgence of American beavers and consequently an explosion of dam building.

Extreme weather events, such as rapid snowmelt and severe storms, impact water quality in major river systems. Droughts and floods are becoming more frequent.

Fendorf and colleagues monitored the effects in East River - a scenic 40 mile long stream.

The study revealed the dams increased nitrate removal by nearly 50 percent - boosting water for oxygen-breathing aquatic organisms.

Initially, lead author Dr. Christian Dewey at Oregon State whose mascot is a beaver, had set out to track seasonal changes in hydrology.

"Completely by luck, a beaver decided to build a dam at our study site," Dewey said.

"The construction of this beaver dam afforded us the opportunity to run a great natural experiment.”

The team reviewed data on water levels gathered hourly by sensors installed in the river and throughout the riparian area.

They also collected water samples, including from below the ground's surface to monitor nutrient and contaminant levels.

The researchers compared water quality along a stretch during a historically dry year, 2018, to water quality the following year, when water levels were unusually high.

They also compared these year long datasets to water quality during the nearly three-month period, starting in late July 2018, when the beaver dam blocked the river.

During periods of drought, as less water flows through rivers and streams, the concentrations of contaminants and excess nutrients, such as nitrogen, rise.

Major downpours and seasonal snowmelt are then needed to flush out contaminants and restore water quality.

The beaver dam dramatically increased removal of nitrate, a form of nitrogen, by creating a surprisingly steep drop between the water levels above and below.

Warm, dry summers following spring snowmelt also produce big level changes, which generate a pressure gradient that pushes water into surrounding soils.

The larger the gradient, the greater the flow of water and nitrate into soils, where microbes transform nitrate into an innocuous gas.

In the East River, the researchers found the increase in the gradient compared to an average day was at least 10 times greater with the dam.

"Beavers are countering water quality degradation and improving water quality by producing simulated hydrological extremes that dwarf what the climate is doing," Fendorf said.

Nitrogen is an especially pernicious problem for water quality as it promotes overgrowth of algae.

It starves water of the oxygen needed to support diverse animal life and a healthy ecosystem.

The study is a reminder that as the future impacts of climate change are holistically assessed, feedback from changes in ecosystems must also be included.

"We would expect climate change to induce hydrological extremes and degradation of water quality during drought periods," Fendorf said.

"In this study, we’re seeing that would have indeed been true if it weren’t for this other ecological change taking place, which is the beavers, their proliferating dams, and their growing populations."