By August 1, 1979, each natural resources district shall prepare and adopt a master plan to include but not be limited to a statement of goals and objectives for each of the purposes stated in section 2-3229. The master plan shall be reviewed and updated as often as deemed necessary by the district, but in no event less often than once each ten years. A copy of the master plan as adopted and all revisions and updates thereto shall be filed with the department.