Texas has over 900,000 ponds with over two-thirds of these privately owned ponds, stock tanks and lakes. These ponds provide a source of water for humans, livestock, wildlife, crops and fish. For these reasons most pond owners should be concerned about the amount of water maintained in their pond. Evaporation is surface water lost to the atmosphere. In a dry year rainfall may not replace the amount of water evaporating from the pond's surface.
Seepage is water lost through the soil.
Well-constructed ponds with good soil may lose one inch of water per month to seepage. Sodium bentonite is EPA approved for use as a pond sealant.