Except for research, scientific or demonstration purposes, the secretary of wildlife and parks shall not stock or restock fish in any private water impoundment constructed by humans and located wholly within lands owned or leased by the individual maintaining such impoundment unless the fish are secured from a private fish grower. These private waters do not include any impoundment constructed, owned, leased or operated by a federal, state or local governmental agency or by a person who has entered into an agreement with a federal, state or local governmental agency that such impoundment will be open to public access and use.