A researcher is retracing the Mississippi River trip from the Twin Cities tothe Quad Cities he first took 20 years ago. Dan Wilkinson is among theresearchers making a trip on a houseboat along that stretch of the river. Thirty-six stops are scheduled during the month-long trip. During a stop inClinton today, Wilkinson says he’s troubled by the silting in of back-waterareas, but he’s encouraged by the interest in riverfront revitalization. Onthe return trip north, the National Aubudon Society team will be joined by acrew from the Discovery Channel. A stop at the Effigy Mounds area inNortheast Iowa will be the focus on the Discovery Channel feature.