The place where I live is the center of the large city of Olsztyn. Beavers are my closest neighbors. There are houses and people all around. Dams built by beavers are regularly destroyed. Low water levels then show the enormity of environmental pollution, and life quickly disappears due to oxygen deficiency. For now, beavers are rebuilding dams. Every day after dark, they start another difficult day, sometimes finding time to rest.