Albert Barnes Commentary Joshua 4:9

"And Joshua set up twelve stones in the midst of the Jordan, in the place where the feet of the priests that bare the ark of the covenant stood: and they are there unto this day." — Joshua 4:9 (ASV)

A different set of stones is meant than the one previously mentioned. One set was erected by God's command at the spot where they spent the night (Joshua 4:3); the other was set up by Joshua on the spot where the priests’ feet rested while they bore up the ark during the people's passage. This spot was near, or perhaps on, the eastern bank . These stones would therefore mark the spot where the people crossed, just as the other stones marked the place where they lodged the night after the crossing; nor, since the stones would only be reached by the water in flood time (and then only by its utmost edge), is there any reason why they could not both be seen and continue in their place, as the writer asserts they did up to the time he wrote.