Iowa Code § 481A.9: Spawning grounds.

To effect sound wildlife management and maintain biological balance as provided in section 481A.39, the commission may set aside certain portions of any state waters for spawning grounds where the same are suitable for this purpose for such length of time as it may deem advisable by the posting of notices in conspicuous places around such area, and it shall be unlawful for any person to fish or to in any manner interfere with the spawning of fish in this area. Any person violating any of the provisions of this section shall be guilty of a simple misdemeanor.