Muddy water in a pond may be caused by the physical disturbance of silt on the pond bottom or by water chemistry that allows microscopic clay particles to remain suspended for long periods (see References 1). Undesirable algae and plants may become a problem when too many nutrients enter the pond through overfertilization or runoff (see References 2).
Natural Insect and Crayfish Control
High numbers of crayfish or burrowing insects disturbing the mud at the bottom of the pond are a common cause of murky water. Control crayfish by stocking the pond with bass, a natural predator. Insect infestations, which you can identify by scooping mud from the bottom and examining it for buried insects or larva, can be controlled by 2-inch bluegill. Limit bluegill to 400 fish per acre of water. (See References 1)
Planting Along Pond Edges
Runoff and wave erosion also cause muddy water. Giving livestock access to the pond can result in defoliated and damaged banks, a situation that allows rainfall to wash the bare dirt into the water. Waves washing against the bare banks pull more dirt into the pond. To reduce erosion, sow ground cover plant seeds to create a buffer along the banks. Add cattails and water lilies in the shallows in areas prone to wave damage. (See References 1)
Spreading Hay or Straw
If clay particles are suspended in the water because of poor water chemistry, spread barley straw or hay around the shore. When hay or straw decomposes, it releases a small amount of acid into the water that causes the clay particles to precipitate out and fall to the bottom in many cases. Never use uncured hay or lawn clippings; they're likely to disrupt the pond chemistry and kill the fish. Use no more than two bales for each acre of water. (See References 1)
Grass carp provide a chemical-free means of aquatic vegetation control for ponds without a large discharge area. Stocking 8- to 12-inch grass carp at a rate of 30 fish per acre of pond vegetation will eliminate the vegetation within a few years in most cases. To generally reduce vegetation levels but not eliminate them, stock 15 fish per acre of vegetation. Use sterile grass carp to eliminate the possibility of unintentional grass carp population spread. (See References 2)
Based in central Missouri, Rachel Steffan has been writing since 2005. She has contributed to several online publications, specializing in sustainable agriculture, food, health and nutrition. Steffan holds a Bachelor of Science in agriculture from Truman State University.