The state has concurrent jurisdiction on the waters of any river or lake which forms a common boundary between this and any other state.
Iowa Code § 1.3
See Act of Congress, Sess. II, Chapter 48, 5 Stat. 742 (1845); Act of Congress, Sess. I, Chapter 82, 9 Stat. 52 (1846); Act of Congress, Sess. II, Chapter 1, 9 Stat. 117 (1846)