Many ponds composed of a variety of soil types are prone to water loss by seepage. This water loss can be controlled by the application of a western sodium bentonite clay called Pond Sealer. Pond Sealer is a high swelling, chemically unaltered, sodium bentonite that contains no additives. It is an economical and environmentally safe way to accomplish pond and lake sealing to reduce seepage losses. Sodium bentonite is a natural clay which has the characteristic of swelling many times its dry size when it becomes wet. When bentonite is applied in a layer of porous soil or mixed with a porous soil, and moistened with water, it forms an impermeable layer. When properly applied, bentonite does not affect the water or wildlife. Pond Sealer is easily applied. In the case of small ponds, bentonite can be applied with simple hand tools and for larger ponds can be applied using ordinary farm equipment. All side slopes should be at a 45 degree or less angle so that the material will stay in place. Pond Sealer makes an excellent liner for new pond construction, for sealing existing ponds with seepages or for spot treating specific problem areas. When sealing a leaking pond to prevent seepage, bentonite can be applied directly to the soil in the pond bottom or it can be sprinkled on the surface of the water and allowed to settle to the bottom.