Many folks have had some trouble with the way the original script worked over the years, including myself. Not saying it won't work or a it's a bad script, just some periodic problems. I decided to take it down, then a couple of springs back, with the rivers running high around here, a few of the regular visitors to the site asked if I could put it back up.
So I searched the forum here and found this thread,
http://www.wxforum.net/index.php?topic=22013.0 and decided to give John from sacreyweather's solution a try.
I've got two of the maps for local rivers on my home page along with this link
https://www.mckeanweather.com/mwriver.php to my Rivers page. If you go to the link in John's post or the River's page on mine, you can click 'Pennsylvania' drop down to change it to Montana to see what the map would look like for your area.
Then if you would like, I could walk ya thru setting up something like this for your site. I've never once gone to the my page and had an error or missing data, and have had a few nice comments from some viewers.
Brad