‘ And so it was that when the priests who bore the Ark of the covenant of YHWH came up from the middle of Jordan, and the soles of the priest's feet were lifted up to the dry ground, the waters of Jordan returned to their place and went over all its banks as previously.'
The removal from the middle of the Jordan, of the Ark with its attendant priests, produced a remarkable effect. For immediately waters began to come down the river bed from the north, steadily increasing until once again they became a river in flood, overflowing its banks. Even the release of the waters were under YHWH's control. Notice the mention of dry ground. That means completely dry rather than being simply not covered by water.