John Gill Commentary Joshua 4:18

"And it came to pass, when the priests that bare the ark of the covenant of Jehovah were come up out of the midst of the Jordan, and the soles of the priests` feet were lifted up unto the dry ground, that the waters of the Jordan returned unto their place, and went over all its banks, as aforetime." — Joshua 4:18 (ASV)

And it came to pass, when the priests that bore the ark of the covenant of the Lord had come up out of the midst of Jordan

According to the command of Joshua in the name of the Lord:

[and] the soles of the priests' feet were lifted up upon the dry land ;

and set upon it, on the bank of Jordan, and shores of the land of Canaan:

that the waters of Jordan returned to their place ;

those that came from above, and had stood on an heap, gradually came down into the channel, and those below that were cut off returned:

and flowed over all its banks, as [they did] before ;

and usually did at this time of the year, see (Joshua 3:15) ; so that there was no decrease or loss of the waters by their failing, and being cut off.