
You'd have to purify the river water first.  I'm not sure how practical
that is with the Mississippi.  You'd better check with health agencies
along the way to see if there are toxic chemicals in the river.  If
it is just microorganisms, those can be filtered or killed, but you
may need activated charcoal or other means to purify from chemicals.
Better be same than sorry.  Obviously, drinking the river without
processing it is likely to make you sick from bacteria and parasites.
-- 
----------------------------------------------------------------------------
Gordon Banks  N3JXP      | "Skepticism is the chastity of the intellect, and
geb@cadre.dsl.pitt.edu   |  it is shameful to surrender it too soon." 