Clay Turbidity

Have you been trying to clear up a muddy pond? There are a couple of steps you can take to help remove suspended clay that can sometimes cause ponds to look muddy. The first is to determine if your pond has suspended clay or something else that causes the cloudiness. To determine if you have suspended clay in the pond, take a clear jar of water and fill it up. Place it on a table and leave it alone over night. If, after this time it is still cloudy or muddy, you probably have a suspended clay problem in your pond.

Once you have determined that it is clay in the water that is causing your problems, you should look to find the source. Do you have grass growing around the pond, or is it just dirt; is there an agricultural field which drains into your pond; has there been or is there currently new construction around the pond; or, are there cattle or other livestock that regularly access the pond? These are common causes for clay turbidity in recreational ponds, and they should be addressed prior to any treatment for the pond. By treating the pond to ‘clear’ the mud without first addressing the source of the mud, the pond will quickly return to its current state.

Following the correction of the clay source, there are several options for treating clay turbidity in the pond. Among the compounds that can be added are cotton seed meal, hay, gypsum, or alum, but never at the same time. You definitely will want to contact your county extension agent for appropriate application rates before applying. Each has the potential to cause clay to fall out of suspension leaving the water clear, but there can be some significant negative side effects if too much of any of these compounds are added. Cotton seed meal (50 pounds/acre) and hay can reduce the oxygen level in the pond dramatically resulting in stress or mortalities in fish and therefore should only be applied in the late fall and early spring months. Alum can cause rapid decreases in pH which can lead to fish mortality if a pond’s alkalinity is not sufficient. Gypsum is safer to use, but is not as effective.

If a pond is suffering from clay turbidity, there are options for a pond manager to help clear the pond, but great care should be taken deciding the best course of action. Many times, liming and fertilizing is the best option to establish a plankton bloom that will dominate any turbidity, in other instances one of the above treatments may be prudent. In all cases, the source of the clay turbidity must be addressed prior to any treatment for long term success in reducing clay turbidity.

For additional questions or information, contact P.J. Waters, Auburn University Marine Extension and Research Center, 438-5690.

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