Any person who by means of traps or other obstructions other than dams prevents the passage of fish up the waters of any river or creek in this state must, on conviction, be fined not more than $100.00, but it shall not be unlawful to erect or maintain a dam on a nonnavigable stream for the impounding of private waters for the production of fish for food and recreation or for the furtherance of any lawful business without providing or maintaining means for the passage of fish up such stream.