The watershed of Monona Bay has expanded over what it was, before settlement.  

Now storm sewers (above, orange) drain much of the University area, including student housing areas and downtown.  After rainstorms, substantial amounts of litter wash to the bay.

The bay is--in effect--a dump for the University.  The UW should build many rain gardens, so that the rainwater sinks in and is filtered, instead of flushing straight to the bay.