Bemidji has never made a practice of this for as long as I know and has had a waste water treatment facility since 1948.  Other municipalities have done this though as recently as 1976 (Blackduck, Cass Lake, etc....).  The Turtle River though is a small, dirty, shallow, narrow and relatively disgusting little stream however.  (From the golf course to Kitchi anyway) and there are many more options if one wanted a 'nice' paddle.   Regarding the Miss., once you leave Cass Lake and get over the dam you will probably not see anybody till you get to Winnie.  

I know the 'sand hill' very well Wally.  And you are right, that part of the river is high traffic.  I was speaking mainly east of Cass.  But, if you start in the morning from Bemidji it's not so bad.  Sounds like were practically neighbors.