Emergency crews searched the Big Sioux River in Falls Park for about two hours Saturday morning looking for someone who reportedly went into the water.
A witness reported seeing a man jump into the river just after 5 a.m.
Crews at the scene determined the call was unfounded and ended the search just after 7 a.m.
Officers later located the owner of the phone. Through subsequent investigation Andrew Haight was arrested for warrants and false reporting.
Authorities take all such calls seriously, but there is special urgency now because of the dangerously swift current caused by the recent heavy rain.
The search included scanning the river with an infrared camera.