It shall be the duty of the local government to administer and enforce any regulations adopted by the department pursuant to section 31-1020 in the same manner as if the local government had enacted such regulations. Such duty may be enforced in a mandamus action brought against such local government by any resident or landowner within the jurisdiction of such local government. If such mandamus action is successful, the local government may be held responsible for all reasonable and actual costs of the plaintiff, including, but not limited to, attorney‘s fees. Neither the regulations enacted by the department nor the boundaries of the base flood or floodway adopted by the department may be modified by the local government without the written consent of the department, except that a local government may adopt a measure more restrictive than that adopted by the department.