Once hunted for their pelts, beavers are back in demand, not for their 
bodies but  for their minds—specifically, for their engineering skills. 
As changing climate  leaves streams short on water in the summer, 
researchers are betting that the industrious rodents could provide a 
natural solution.
Based on a survey of how dams store water, the Lands Council in Washington 
State predicts that reintroducing beavers to 10,000 miles of suitable habitat in 
the state could help retain more than 650 trillion gallons of spring runoff, which 
would slowly be released by the animals’ naturally leaky dams. The council 
began investigating the beaver option after learning that the state was 
considering artificial dam projects that might cost billions of dollars. It argues 
that beavers can do the job at a small fraction of the expense: Restoration, 
maintenance, and monitoring would cost less than $1 million, the council 
estimates. This year the group plans to test its water storage predictions 
with a small-scale reintroduction project that will compare groundwater 
levels before and after beavers settle into their new homes.
The project builds on research from ecologists Glynnis Hood and Suzanne 
Bayley of the University of Alberta, who studied records spanning 54 years 
from Elk Island National Park in Canada. They found that during periods of 
drought, wetlands held nine times as much water during years when beavers 
were present than when the animals were absent due to trapping. “Beavers 
concentrate water into areas where they want it,” Hood says. “They engineer 
the landscape to their advantage.” Michael Pollock, an ecosystems analyst 
with the National Marine Fisheries Service, is restoring the animals to 
Bridge Creek in eastern Oregon, with promising initial results. Since dam 
support structures were installed in 2008 to help colonies get started, 
groundwater levels there have begun to increase.