Since there is a small village in Slahpa, I would assume that anybody who has to commute daily to the power plants at lake Bryn south-east from there would live in Slahpa since they cantake a road instead of commuting daily with a boat from Kjøpsvik, after which the person would still need a car to drive up to the plant.
Maybe there is a higher chance of a group hiring a boat that you can go along with than someone going there daily for work on his own boat.
There might be a chance however that there are daily boats with supplies going to Slahpa lodges and residents that you can tag along on.
Credit:stackoverflow.com‘