Tailwater is irrigation runoff that will either be lost to evaporation or drained into the soil. Tailwater recovery systems vary according to the different type of tailwater that is being saved. For example, tailwater systems are used to recover released dam water and flood water as well. Naturally, tailwater recovery systems are important to sod farmers and other large agricultural enterprises.
A tailwater recovery system reuses water so that it can be returned to its original task. Relating to agriculture, it is a system that recovers irrigation water by using a drainage swale at the low point of an irrigated area and allows that water to be captured and reused for additional irrigation.
According to the University of California at Davis Division of Agriculture and Natural Resources, it is best for the flow of water to be fast in a tailwater recovery system. The reason for this is that there is a greater chance that the absorption rate of water into the soil will be more uniform when the water is running quickly over the soil. Therefore, the water can be recovered and released again and again over the area to be irrigated with the final result being that the entire area gets a fairly uniform amount of water that is absorbed into the soil.
There are a number of ways the runoff water that is collected by the tailwater recovery system can be disposed of:
- The water is allowed to pond at the end of the irrigated field
- The water is allowed to flow into other fields that have not been irrigated
- The water is allowed to run off the field, collected, and discharged to a natural body of water
- The water is collected and pumped into a pond where it is not used again
Although establishing and maintaining a tailwater recovery system incurs costs of its own, the benefits to the environment and to the overall operation costs and efficiencies are immense. A tailwater recovery system minimizes the environmental impact of the runoff water, improves irrigation efficiency, reduces water costs, simplifies irrigation water management, and removes standing water that can cause damage to crops and resulting crop loss.
As a rule of thumb, the amount of tailwater that should be used in an irrigation system is 15% to 25% of the total volume of water used in the system.
Tailwater recovery systems vary depending on the size and scope of the project and the type of crop and field being irrigated. Costs also vary depending on the type of system used and the size of the project. Therefore, each application of a tailwater recovery system must be evaluated individually to arrive at which system is appropriate for the task at hand.
In 2010, Bethel Farms partnered with the South Florida Water Management District and the Natural Resources Conservation Service to construct a tailwater recovery and storage facility at Bethel Farms headquarters. Designed to subsidize 300+ acres of turf with irrigation water, the containment area of 5 acres has a maximum depth of 15′ and cost over $250,000 to build.
A similar system is now being installed at the County Line Farm on SE Notts Dairy Rd. in Arcadia, Florida. This project is part of the continuing effort to reduce groundwater consumption and improve water quality.