Katy is not famous for anything. It was a sleepy rice farming community in the past if you want to consider that significant. Rice is still grown in the area, but not as much as it once was. It's a desireable place as a quiet, diverse "suburb" of Houston, though it is a fully functioning city in of itself with it's own government and city services.
As for lakes, there are not any public lakes; there are ponds everywhere, most on private property. Mary Jo Peckem (sp?) has a large pond where you can "fish", but you can't really do anything there in regards to water sports. There is a subdivision where you can actually water ski, and park you boats, but it is a novelty subdivision and you must live there to use it. They dye the water blue.
There are no waterways, or bodies of water that I know of where you can canoe; maybe some of the retention ponds (aka "lakes") in some of the subdivisons? Not sure.
That said, I live in Katy proper, and I really like it; only a couple of blocks from my house are horses, and on the other side, cattle, huge oak trees, pine woods. It is very quiet, laid back, and great neighbors.