The board of managers shall develop a plan for agricultural drainage and soil conservation to promote optimal crop production by establishing and maintaining drainage systems that promote public health, safety, and welfare. In developing the plan, the board of managers: shall engage the services of private engineers; or may use the services of planners and engineers of local, State, and federal units of government. A member or an agent of the board of managers or a member or an agent of the board of viewers: may enter any land to make surveys and examinations for developing a plan; and is liable for actual damage done to any land entered during a survey or examination.