This video from the USA says about itself:
26 March 2013
Presenter Dr. Jimmy Taylor shares information about Oregon‘s state animal – the beaver – and how we benefit from their activity. Taylor is a supervisory research wildlife biologist and field station leader for the National Wildlife Research Center in Corvallis, Oregon. His research project focuses on understanding human-wildlife conflicts and improving management strategies to reduce damage by forest and aquatic mammals, with an emphasis on non-lethal tools and techniques.
North America’s largest rodent, the beaver, was once the most widely distributed mammal but virtually trapped to extinction in the early 1800’s for its pelt. A decline in demand for its fur and proper wildlife management helped beaver to become reestablished in much of their former range. While beaver foraging and building activities can cause flooding, damaging private property; beaver ponds and dams are also good for Oregon’s native fish and other wildlife. Beaver activities can also benefit private landowners by controlling downstream flooding and creating wetlands which improve water quality and facilitate ground water recharge. If managed correctly, conflict with beaver can be minimized.
From PLOS ONE:
Alteration of stream temperature by natural and artificial beaver dams
May 17, 2017
Beavers are an integral component of hydrologic, geomorphic, and biotic processes within North American stream systems, and their propensity to build dams alters stream and riparian structure and function[s] to the benefit of many aquatic and terrestrial species.
Recognizing this, beaver relocation efforts and/or application of structures designed to mimic the function of beaver dams are increasingly being utilized as effective and cost-efficient stream and riparian restoration approaches. Despite these verities, the notion that beaver dams negatively impact stream habitat remains common, specifically the assumption that beaver dams increase stream temperatures during summer to the detriment of sensitive biota such as salmonids.
In this study, we tracked beaver dam distributions and monitored water temperature throughout 34 km of stream for an eight-year period between 2007 and 2014. During this time the number of natural beaver dams within the study area increased by an order of magnitude, and an additional 4 km of stream were subject to a restoration manipulation that included installing a high-density of Beaver Dam Analog (BDA) structures designed to mimic the function of natural beaver dams.
Our observations reveal several mechanisms by which beaver dam development may influence stream temperature regimes; including longitudinal buffering of diel summer temperature extrema at the reach scale due to increased surface water storage, and creation of cool—water channel scale temperature refugia through enhanced groundwater—surface water connectivity. Our results suggest that creation of natural and/or artificial beaver dams could be used to mitigate the impact of human induced thermal degradation that may threaten sensitive species.
In this way, beavers save sensitive species like salmon, which cannot live in warm water.
Interviewed by Dutch daily De Volkskrant on this today, Belgian Antwerp University beaver expert Kristijn Swinnen thinks that the European relatives of American beavers may in similar ways benefit European relatives of American salmon and other species threatened by climate change. European beavers came back in the Netherlands only recently after having been exterminated there in the nineteenth century.