Here ya go:
Physically removing cattails is a viable option when they first invade a pond or begin to spread from an area the pond owner wants them confined to. New cattails can easily be pulled by hand once the new green growth is about 6 inches above the water surface. Be sure to reach to the pond bottom and remove the entire plant, including as much of the attached root system as possible. Success of this technique depends on the pond owner being vigilant and regularly pulling out new growth.
An alternative, and somewhat easier, mechanical method is to continuously cut off the new green shoots as they emerge from the water. This can be accomplished with a sharp pair of shears or with a gasoline engine-powered trimmer (weed eater). Safety note: Never use electrical powered equipment around the pond, as such use could result in electrocution. This method�s goal is to prevent the leaves from reaching maturity, upon which time they produce and transport large amounts of food to the root system. A root system that is deprived of its food supply will eventually wither up and die. Again, persistence is key for this method to work.