About 25 years ago my folks dug a spring-fed pond approximately 1 acre in size varying in depth from 5-12 feet. About 8 years ago my dad got a pair of swans from the local Conservation authority. Before that, the water was clear, you could see to the bottom almost everywhere (unless the silty, muddy bottom was disturbed).

Immediately the swans stirred up the water due to their feeding technique; this was not a surprise. However, last June for the first time the entire pond turned a bright green, which I assume is an algae bloom (the pond looks the same this year).

We don't fertilize anywhere near the pond and have made extra efforts to only plant evergreens near the pond to prevent leaf buildup in the water. My theory is that our pond simply isn't big enough to deal with the 8 years of accumulated swan crap and the algae bloom resulted from the nitrogen rich water.

Any comments/experiences would be appreciated. I'm trying to build a case to get rid of the nasty beasts and let the native waterfowl come and go as they please.