A large part of the agricultures with animal husbandry are unbalanced in the respect that the feed for the animals is produced on other places, and is imported into the farm.
Such farms are common in south Sweden. 60% of the Swedish milk is produced in Skån and Blekinge, in the very far south of Sweden.
A very large part of the pig production is situated in the watersheds of the rivers Lagan, Braån and Helgeån. These rivers drain into the bays of Laholm and Hanö, which are heavily polluted of nutrients.
The problem lies in the HEAP traps that is formed when a large part of the nutrients (more than 2/3) in the feed is converted to manure, which is put into the fields close to the farms.