Climate change is making the American West hotter and drier, shifting the timing and strength of moisture extremes.

But research in the journal Nature Communications suggests beaver dams could more than offset the harmful effects such changes have on water quality.

Fluctuations between droughts and downpours reduce river contaminants by driving water into nearby soils for filtration; for example, nitrates that feed harmful algae growth are instead released by soil microbes as harmless nitrogen gas.

When a beaver made itself at home at a study site on East River, a major Colorado River tributary, researchers found that its dam caused the same helpful pressure gradient, but an order of magnitude stronger and 44% more effective at filtration.

Beavers are expected to expand their ranges under projected warming and drying conditions.