There was a presentation about the current state of Mt. St. Helens at today's Communications Academy (
http://www.commacademy.org/ ) One of the handouts was about Mt. Rainier with a map showing potential lahar flows.
The main USGS Cascades site is here:
http://vulcan.wr.usgs.gov/There are pages about all the major Cascades volcanoes, including hazard reports for each. I don't see the Rainier brochure on the website, but this is the map:
http://vulcan.wr.usgs.gov/Volcanoes/Rainier/Publications/FS065-97/FS065-97_map.pdfDave F>