Well, those bits are all leaves. It rained today actually, so all the leaves came down with the rain. That's all leaves floating on the water. But uhh, it's not brown so much as it is green? I live near the Great Lakes, so there's clay everywhere. It's not dirty to me. I've been up to Muskoka and it looks the same. Hell, I've swam in the Thames river and it looks like this kind of brown: http://upload.wikimedia.org/wikipedia/commons/c/cf/Thames_london_ontario_north_branch_2.jpg Where are you from? Don't you have creeks?
Northern Ontario....where the water is clean and clear....even most of the creeks...unless we get a huge rainfall We have clean water.....but we insist on putting brown shit in the air