The hydrographical and ecological changes in the deep part of the Bornholm Basin in response to pumping well-oxygenated so-called winter water down to the greatest depth are investigated. By pumping 1000 m3s-1, the rates of water exchange and oxygen supply increase by 2.5 and 3 times, respectively. Anoxic bottoms should no longer occur and hypoxic events will become rare. This should mean much improved conditions for successful cod reproduction, extensive colonization of fauna on earlier periodi