"Yeah, it was really exciting because I knew that we were... that there was this great natural experiment happening right... right before us," remembers Christian Dewey, Ph.D., of Stanford University.
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Dewey was a Ph.D. student at Stanford when he set out to study changes at a tributary of the Colorado River in wet and dry years. But, while the team was setting up instruments to measure things like water quality, a team of beavers was moving in and set up shop themselves, damming the river.
"And we were set up to capture the hydrologic impacts of this event. And then also the... the impacts on water quality, because we had everything installed to collect samples and measure the things that you measure to determine water quality," says Dewey.
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By measuring changes in water quality, Dewey and his Stanford professor, Scott Fendorf, Ph.D., were able to document the benefits, especially during drier years when water quality typically degrades. As the beavers' dam spread the river water through marshy banks, known as riparian zones, the researchers documented a cleansing effect, and a drop in contaminants and excess nutrients, such as nitrogen.
"So when we have these long periods without a lot of rainfall, they're going to step in and start changing the hydraulics of the river systems. And that's going to be to our advantage...right? What they're doing is that they're increasing the filtration capacity of the river. So even when we have lower water, lot of lower water flow, random guess; improved water quality by the... by the effects of the beaver dams," says Fendorf.
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The data comes at a time of increased interest in nurturing beaver activity, even in semi-urban settings like Martinez, where one celebrated group had discovered dam building in 2007. In a separate paper, Felicia Marcus, a Landreth Visiting Fellow at Stanford University's Water in the West program, connects the dams to a drought strategy known as "nature based solutions."
"You end up with flood control, you end up with sediment control," says Marcus.
She says a number of states have set up programs to compensate land-owners where beaver activity damages property. Meanwhile Dewey and Fendorf are hoping their study will focus attention on how natural ecosystems could be stressed by drought and climate change in the future. And the benefits of supporting natural populations that might be able to help.
"So for me, that's the primary message is for us to appreciate them and to try to really do everything we can to have them naturally repopulate," says Fendorf.