Put on heavy gloves and a pair of waders and make your way through the cattail infestation. Pull the larger cattails out with your hands. Prevent new growth by pulling from the base of the cattail to remove roots from the soil.
Cut the small cattails with a gas-powered trimmer. Monitor new growth and trim the cattails when they reach a height of 6 inches. Slow the rate of growth by cutting the stalks with a hand trimmer. When winter approaches, trim the stalks just below the surface of the water.
Rake the cattail stalks and remove them from the water. Prevent reseeding by taking the stalks to an area far away from the pond. Make sure the wind doesn't blow the seeds or stalks back into the water.