There were several incidents where powder horns were lost or got wet but when the canoe got swamped there was no powder lost.
On Feb 1st 1806 Capt lewis wrote " today we opened and examined all our ammunition, which had been secured in leaden canesters. we found twenty seven of the best rifle powder, 4 of common rifle, three of glaized and one of the musqut powder in good order, perfectly as dry as when first put in the canesters, altho' the whole of it from various accedents has been for hours under the water. these cannesters contain four lbds. of powder each and 〈contain〉 8 of lead."
This was 40 pounds of powder and only seven months from the end of the journey, not short powder by any means....LK