Look at d. I guess I'll do what Don said and ask a local detecting club what they do if anything. I hope they will treat this out of towner with some respect. After all I'll be hunting on their grounds.
(1) Conduct in parks. It shall be unlawful for any person while on property or in buildings under the operation and control of the park board to:
a. Conduct himself in an unusually loud or disturbing manner; use threatening, abusive, insulting, indecent, obscene or profane language; or harass, annoy, curse at or intentionally jostle any patron of any public park.
b. In any way interfere, by the use of physical force or by the threat of such force, with any person peacefully moving in and about the grounds and buildings, except for a law enforcement officer or employee of the parks in the performance of his duty.
c. Throw stones, rocks, sticks, bottles or other similar things by hand or otherwise.
d. Mark upon, tear up, injure, deface, cut, dig or in any other way intentionally injure or impair the usefulness of structures, grass, trees, shrubs or plants, pavement, sidewalks or roadways.