This is a good example of why water/soil tests are a good idea. If you had a before and now water test results you could compare and see what has changed.
How many/much willow coverage is involved? Willows at the waters edge can use up some (but not large amounts) of fertility from the water. Their death would leave more fertility in the water to grow plankton. I don't think that would cause large changes however.
I wasn't even aware that you could have pond water samples tested. Are the results similar to soil tests that list such things as pH, P, K and Ca in mg/l. Do any test labs advertise these services on Pond Boss?
The willows that were sprayed are all smaller bushes which have just sprung up within the past five years. Most are less than six feet tall with the largest being about twelve feet. I was originally going to allow the willows to grow to provide cover for the FHM and crayfish but they have started to take over the shoreline in places.
