Complex sentence: A bit further into the mountain there is a big lake called Vinstravatnet with a lot of fine trout, but with local disputes between people from Valdres and people from Gudbrandsdalen they couldn't leave their boats behind.
Split into simpler sentences: A bit further into the mountain there is a big lake called Vinstravatnet with a lot of fine trout. As a result of a dispute between people from Valdres and people from Gudbrandsdalen people could not leave their boats behind.