Loop,
How far downland is your property from the area where the chicken squeezings are laid out? You stated that the pond has experienced this color the last two summers, do you know if the poultry farm just started spreading the goods two summers ago or have they been doing this for some time? How old is the pond and have you had any fish problems over the past two years?
Bill you mentioned nitrogen, which I'm sure you know is one hot component of chicken poo, but in Loop's second picture, the water near the shoreline looks more blue-green like Greg mentioned. The trees reflection may be misleading.
If the poo gardens are some distance from your pond, I think Eric's comment about the natural fertility of the land may be worthy of discussion.
No expert here, just some thoughts.
