10.28.110 Restrictions on the use of personal watercraft on freshwater lakes.
Personal watercraft shall not be operated in San Juan County on fresh water lakes with public access, which are: Sportsman Lake, Hummel Lake, Mountain Lake, Cascade Lake, Egg Lake and Killebrew Lake. (Ord. 7-1998 § 4)
10.28.120 Restrictions on the use of personal watercraft on the marine waters of San Juan County.
Personal watercraft shall not be operated on the marine waters of San Juan County.
The provisions of this section shall not apply to:
A. A personal watercraft engaged principally in commercial operations constituting an act of interstate or foreign commerce and so long as during such the personal watercraft is operated along the most direct route practicable;
B. A personal watercraft operating under a permit issued by the United States Coast Guard;
C. A personal watercraft operating under a permit issued by San Juan County;
D. For emergency purposes when there is reasonable belief that such use is necessary to protect or preserve persons, animals or property. (Ord. 7-1998 § 5)
It reads to me like they're banned on those specific lakes and in all salt water in San Juan County.