Our pond will do this in the winter right after a thaw or melt. We have a gravel road out front and when the wind blows from the road to the pond fine dirt will stick in the ice and snow. When this melts the pond will turn brown on us. This fine dirt will settle out in time but is really fine.
The water gets clearer as the water temp drops. We can see over 4 feet when all summer 18-24"s max is all we can see. After a good thaw it gos back to 20"s or so but quite sure its the dirt from the road.