Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Cold tolerant FA species?

Topic: "" Nutrients and siltation from over 60 acres of run off from row crop Ag fields flowing into our pond.""

You are in a tough place managing a pond with constant incoming agri-nutrients. This creates a BIG plant problem for a pond. Been there done that. As you know nutrients grow good row crops and when those nutrients are in your pond they do the same thing to grow bigtime crops of pond algae & plants. As long as the watershed feeds the pond and remain in the pond, the pond will want to grow a plethora of green stuff. By continually suppressing the FA you are allowing an accumulation of a bigger and bigger total nutrient sink accumulation to develop in the pond. This will cause the pond to want to respectively grow more and more green as time passes. What grows is basically determined by the historically accumulated and fresh input load of nutrients.

If the pond water is usually clear (4-5ft+) the balance of N:P is favoring FA and not phytoplankton. Some forms or types of FA are known Phosphorus Hogs. High amounts of phytoplankton will usually shade the water enough and starve the FA to a point that FA would be suppressed. If the water has low visibility due to silt turbidity, then the nutrient load is very high to create overloads of FA from just the shallow illuminated area / zone of turbid water while noticeably less or none grow in deeper low light areas.

Since we do not know the specific type of FA that is causing the problem, we do not know if the current type is the same specie/s ? type that was prevalent in earlier years. Constantly suppressing the FA with the same annual procedure likely allows the FA to adapt and/or resort to or develop a new introduced specie to the same old treatment methods or it could form a more tolerant strain or type of FA.

I had a very similar pond originally built that received similar agri-runoff. I then rebuilt the 35 yr old pond and rerouted the inlet water. This noticeably reduced a lot of my pond problems. In your situation, I would explore various methods of nutrient abetment for ways to consume and bind excess nutrients that would could be bound then ideally be removed. IMO some form of plant excess growth will always occur and need to be dealt with as long as the high inflow of agricultural nutrients annually enters the pond.

Once nutrients are introduced into a non-flow through pond some sort of harvest or binding is about the only way nutrients can be actually removed. Compare the amount of agri-harvest used on the 60acre watershed and then transfer a similar amount of needed crop harvest work for the respective acreage of your pond.

IMO constant, regular, and continual chemical binding of a constant high input of nutrients is or will eventually be detrimental to the pond ecosystem as a whole.

Floating plant islands are a good non-algaecide possibility, however with the high annual nutrient input to the pond a lot of island surface area would be needed to see a good impact. Homework needed for island surface area vs nutrient load/s. Nature demands that something will utilize the available nutrients. I would check with the floating island's Bruce Kania to see if they harvest any plant materials from their floating islands other than harvesting just fish as their form of nutrient removal / abatement. Bob Lusk has been associated with Bruce Kania for a few of the PB mag articles. There are several good videos on Youtube for building low cost large floating islands.