I do not have any of the data here, but I do know that Rick Hutchinson used to monitor the river temperature all the way from Old Faithful (probably upstream from there) to Madison. My mental recollection is that in late summer he obtained temperatures in the low 80s Fahrenheit in the Lower Basin above Nez Perce Creek, temperatures in the 70s downstream from Nez Perce. Scott Bryan In a message dated 10/1/2011 6:18:27 P.M. US Mountain Standard Time, kreeves5 at cox.net writes: I myself have never swam in the Firehole river, but I have seen many swimming below Firehole Cascades (well above Firehole Falls), and I have placed my hand in the water there. It sure felt much less than 110 degrees F. -------------- next part -------------- An HTML attachment was scrubbed... URL: </geyser-list/attachments/20111001/ae181b62/attachment.html>