The Water Permit Programs Unit oversees the administration of the original public waters inventory conducted in the late 1970's and maintains the inventory records. The original Public Waters Inventory (PWI) map mylars are still used to generate paper copies of PWI maps, which are available for sale at Minnesota's Bookstore. The Public Waters Inventory Program responds to inquiries about the public waters inventory hearing process and record. In recent years, because of litigation against the DNR, the program modified the original PWI maps of counties that contained designated trout streams. The litigation resulted in additional public waters regulated by the DNR.