(1) The county legislative body may authorize milldams, fish traps, and other local improvements and erections in watercourses in the county, and fix the rates of toll or charge, under the limitations, restrictions, and conditions deemed proper, and remove them when the public interests require.
(2) The application for any of these purposes shall be by petition, in writing, stating the nature and object of the proposed improvement or erection, notice of which shall be given as prescribed in the case of toll bridges, ferries, and causeways.
(3) The county legislative body shall be satisfied that the preliminary notice has been given before acting on the application, and may then decree as the public interests seem to require.
(4) No milldam, fish trap, bridge, or other improvement shall be allowed so as to interrupt or in any way injure or impair the navigation of any navigable watercourse of the state.