I read the information re: spreading hay and followed the suggestion to check the water first.

After taking a sample at 5 feet (about a foot from the bottom), I expected to find brown, cloudy water but found it was almost clear with a slightly brown tint; about the same as leaving a teabag in hot water for 30 seconds. It's wierd because when you look at it from the surface it looks dark and murky with visibility to about 3 feet.

Probably best to leave well enough alone, for now.