The "tee pees" are the anchor towers upstream from the pontoon bridge that had cables running to the pontoons to keep it from having a "rainbow" caused by the current.
Occasionally, when there was a flood surge, they would disassemble the pontoon bridge to keep driftwood, etc. from collecting on the upstream side of the thing and ripping it apart. The anchor towers also collected drifting debris and sometimes the large amount tore them down or apart. The Dardanelle Pontoon Bridge & Transfer Co. had a couple different steamboats (over the years)and a pile driver they used to maintain the bridge and towers and to ferry people, mail, and items of commerce across the river when the bridge was out of service.