https://www.sciencealert.com/rivers-in-the-us-are-changing-colour-decades-of-satellite-imagery-reveal/amp
I'm really surprised this idea hasn't caught on years ago: correlating remotely sensed data of water body color to indicators water quality. Growing up in farm country, rivers were the color of coffee with cream, and about as clear. Chicago water was green, northwoods water was root beer, and if you were near a paper mill the streams were the color of whatever dyed craft paper they were making that day. We knew we couldn't see all pollutants, but if you have a lot of silt you should be able to suppose a lot of fertilizers and pesticides.
I'm really surprised this idea hasn't caught on years ago: correlating remotely sensed data of water body color to indicators water quality. Growing up in farm country, rivers were the color of coffee with cream, and about as clear. Chicago water was green, northwoods water was root beer, and if you were near a paper mill the streams were the color of whatever dyed craft paper they were making that day. We knew we couldn't see all pollutants, but if you have a lot of silt you should be able to suppose a lot of fertilizers and pesticides.