How can we protect, sustain, and restore lakes, rivers, and freshwater fisheries?

Answer 1

By applying some or all of the following options:
-decrease emissions of contaminants like mercury and PCBs
-carefully study and weigh the consequences of building dams, canals, reservoirs, etc.
-educate recreational fishermen about the threats of invasive species
-carefully set caps on commercial and recreational fishing, based on direct scientific evidence
-implement Best Management Practices on farms, plant vegetation around shorelines, encourage urban dwellers to keep storm sewers free of contaminants, etc etc., in order to prevent excessive nutrient loading of the lakes
-implement fee scheme so that people pay for the real cost of their impact on a waterbody, rather than take it for granted that the waterbody is there to be destroyed at will
-legislation to prevent or limit water use for non-essential functions, such as pressure drilling for oil sands
-get locals around a waterbody involved with its protection and preservation through community committees

I can think of so many more, but this list would make me happy :)

Answer 2

We can get rid of all industry in the USA. Which we pretty much have already done, that since nearly everything made today is in the worst polluted part of the world China, and our good old USA is on the way to cleanliness.