I went tubing through this company on the Saluda River in Columbia, SC. The staff was nice, the tubes were fine.
The problem was the river was not fit for swimming. It smelled and in slow water had a nasty film floating on the top. I later researched it (wish I had done so before) and there are municipalities that are discharging into the river beyond what it can handle. Possible also industrial discharges.
Once I finally got out of there, couldn't find a shower fast enough.
Thus, even though the company was very nice, and they can't help the quality of the river, I would not swim, tube or set foot in the Saluda.