Of our state's great rivers, the Minnesota is the most grievously abused; because, as any river rat knows, agriculture does horrible things to rivers. It pumps them full of sediments, fertilizers, and, um, animal shit. If it wouldn't lead to mass starvation, rioting and anarchy, we'd all be better off if the practice were permanently banned. Sadly, for most of its 300-mile length, the Minnesota River runs through the heart of the state's farm country. Most of the year, the water is turd-brown; when you have a fish on the line, you can seldom make a visual identification until it breaks the surface. All that said, the Minnesota River has become a little cleaner in recent years. And while it is not yet swimmable, it is eminently fishable. By our reckoning, nothing tops the stretch near Chaska. The Minnesota does well in the piscatorial variety department, holding the usual game fish (such as walleyes and northern pike), tons of common rough fish (carp and drum) and ern pike), tons of common rough fish (carp and drum) and plenty of obscurities (bowfin and gar). A few years ago, a four-foot-long paddlefish turned up in the waters by Burnsville. But the Minnesota is ruled by catfish, both flatheads and channels. If there is a better fighting fish in our waters, we don't know what it is.