After reading through the first few dispatches relating to the action at St. Charles, and also with reference to the DICTIONARY OF AMERICAN NAVAL FIGHTING SHIPS, I have come to the conclusion that General Hindman may have had a valid reason for his statement about the CSS PONTCHARTRAIN being on the White River.
Referring only to volume 23 of the ORN, several dispatches indicate that the Union vessels had only entered White River one or two days prior to the action at St. Charles [see dispatches on pages 165-170].
The tonnage of the USS ST. LOUIS was 512, as opposed to that of the CSS PONTCHARTRAIN, at 454, yet the USS ST. LOUIS was able to move at least 63 miles above St. Charles, as late as June 18, 1862 [ORN 1, 23, 176]. Lieutenant McGunnegle, commanding the ST. LOUIS, indicates that it was on that date that the river was falling (not enough at that period to prevent the gunboats from retreating back down the river).
Lieutenant Dunnington of the CSS PONTCHARTRAIN states, "At the request of Major General Hindman I had placed in battery at St. Charles (which is 90 miles above the mouth of the river) two rifle 32-pound guns belonging to this vessel and two rifle 3-inch fieldpieces that I found at the arsenal here [at Little Rock]." This, plus the fact that the Union gunboats did not appear on the White River until June 16, the day before the action at St. Charles, would seem to indicate that at some time prior to that date, the CSS PONTCHARTRAIN had indeed been on the White River. [ORN 1, 23, 202]
I think that, until concrete evidence comes to light, perhaps in the form of deck logs of the CSS PONTCHARTRAIN, or additional papers of the vessel's commander, Dunnington, I am of an open mind about whether or not the Confederate vessel had been on the White. The dispatches currently available do not seem to give conclusive evidence one way or the other, so it would be rather unwise to make an assumption based on what is currently available. Meanwhile, I will continue to peruse the interesting reports of that action, included in volume 23 of the ORN. The land battles are not really of much interest to me, but when read in conjunction with Naval actions, they do appeal.