The site of any aquaculture operation is very important. A crawfish pond site needs to meet several criteria to help to assure the success of the venture. First, the soil needs to have an adequate clay content to it so that the pond will hold water. Typically, the soil should be 20% to 30% clay. Generally, if you can ribbon out a hand full of damp soil to a length of 3 or more inches between your index finger and thumb, you can feel fairly comfortable that your soil contains enough clay.
Second, the land needs to be fairly flat. Crawfish ponds typically only hold 18 inches of water and there should only be about a 6 inch change in elevation between levees (or dikes). If the land has too much of a slope to it, too much land will need to taken up in the numerous contour levees. This will not allow enough pond area to raise the crawfish in.
Third, crawfish require moisture in the soil in order to survive the summers underground, in their burrows. Land with a high ground water level, as is prevalent in eastern North Carolina, or low land that receives considerable runoff and stays damp is ideal. Often times some of the poorer farm land make some of the better crawfish land.
Finally, the crawfish pond should be located near a convenient water source. This source can be a surface source or a ground source. The source needs to be capable of supplying 60 gpm per acre to the pond (the amount of water necessary to replace 8 acre-inches of water in about 4 days). Because of the volume of water required, the least expensive source of water should be considered first.
There are advantages and disadvantages to both surface water sources and ground water sources. Surface sources are generally less expensive to pump. Usually, the Total Dynamic Head is less than 20 feet, keeping the energy requirement at a minimum. However, surface waters are usually more prone to contamination, both biological and chemical. Biological contamination, usually in the form of unwanted predator fish, is the most harmful to a crawfish pond. When utilizing a surface source of water, a filtration screen made of 1/4 to 1/2 inch expanded metal grating or hardware cloth should be used at the pump discharge point. This size screen should remove most of the larger fish. Fish that are able to pass through the screen and survive should be too small to pose a threat to the crawfish population. It is advisable to have a side barrier on the top level of the filtration screen, as seen in Fig. 1, to prevent the larger, filtered out fish from flopping off the screen and into the pond. Chemical contamination can pose a risk any time the water being considered for use in a crawfish pond is from runoff. Crawfish are very closely related to insects and most cases, insecticides have the same affect on crawfish as they do on the target insects.
Ground water is usually of very high quality and consistent quantity but can be very expensive. Wells large enough and deep enough to obtain adequate volumes of water can be very expensive to dig, often times in the 10's of $1000's. Deep wells usually have a Total Dynamic Head of over 100 feet which can cause them to expensive to operate. Also, groundwater has no dissolved oxygen in it. Therefore, the groundwater needs to be pumped an additional 4-6 feet into the air so that it can be dropped through an aeration screen. A properly designed and built aeration screen should be capable of increasing the oxygen content of the well water to saturation.