To improve stream health and help restore wetlands, ecologists have increasingly looked to beavers for inspiration. Stream-spanning structures made of vegetation, called beaver dam analogues (BDAs), offer a cost-efficient way to slow down moving water. A new study suggests they have another benefit: improving water quality downstream. This week in Applied and Environmental Microbiology, researchers report that BDAs significantly reduce the amount of a waterborne protozoal pathogen, Giardia duodenalis, in stream water flowing through a cattle ranch in California. “We found that slowing down the water in these creeks allowed these pathogens, which can cause disease in animals or people, to be removed by the BDA structures,” said epidemiologist and senior author Woutrina Smith, DVM, MPVM, Ph.D., from the University of California, Davis.