Beaver dams a low-tech solution to stormwater management in Atlanta park

Manmade beaver dams have just been installed along a creek in Atlanta’s Blue Heron Nature Preserve and could offer a time-tested, natural method to manage stormwater runoff.A

The effect of the manmade beaver dams is the same as natural beaver dams – water backs up behind the dam and forms a pond, where some water can soak into the earth and groundwater. Water that does seep through the dam flows downstream at pace slow enough to not erode creek banks.

Beaver dams are a modest method to clean streams, according to Ed Castro, president of ECL, the company that installed the dams at the nature preserve.

They’re so smart they even got the state to pay for the project with a clean water grant. You know it’s a pretty great day for beavers when a bunch of bureaurocrats write a check for the work they would do for free. Now if we could just get them to stop writing the other kind of checks. You know, the ones they pay to BMP or USDA to kill them.

Blue Heron’s system of dams was built with locust trees harvested from Castro’s tree farm in Newton County. They were nuisance trees and he was pleased to find a good way to repurpose them. The tree trunks became the upright poles in the dam, and branches and underbrush were woven in a horizontal fashion among poles that had been installed in pairs. Each dam runs 12 or so poles wide, depending on the width of the creek at a given point.

“The idea was to mimic a natural approach that a beaver might have,” Castro said. “We’d weave the poplar, the box elder – the biomass – in between the logs, mimicking beavers as they cut it down and start adding material, like a bird building a nest. They’re using a collection of natural resources and building it their way.”

Hey if you’re REALLY LUCKY some local beavers will move in and take over. Their funding stream is more reliable and consistent. And they stick around on the job and make repairs for free.

Good Luck!