A restoration case study called “Beaver re-introduction” is the Swedish contribution in the new EU Green Deal project MERLIN*. The case study will have a before-after design, which means experimental construction as well as demolishment of 60 beaver dams in Sweden, of which 10 will be located in the Vindeln River catchment including Krycklan. The location of the other study areas are still to be decided. It is a four-year project and preferably, with two years of sampling before the measure (construction/demolishment) and two years of sampling after the measure. The studied parameters will be similar in all case studies within the MERLIN project despite studies of quite contrasting characteristics and type, the focus on beavers will as an example only be in Sweden. So a whole lot of biota sampled as the focus is on biodiversity aspects with elements of potential ecosystem services. Likely parameters to be studied are e.g. fish migration, mitigation of climate change effects (flood and drought resilience, formation of greenhouse gases), methylation of mercury and pathogens (especially Francisella tularensis causing tularemia [Swedish harpest] and Sindbis virus causing Sindbis fever [Swedish Ockelbosjukan] in humans) in beaver systems.