Do Tailwater Recovery Ponds Help Growers?
by Shawn T. Steed
Agent, Environmental Horticulture Production
UF/IFAS Extension, Hillsborough County
SWFWMD and farmers may have slightly different ideas on the purpose of tailwater recovery ponds. In fact, even I was under a big misconception regarding the purpose of these ponds. Many growers are operating on a false assumption that ponds are a way to capture and store excess water for use whenever needed or in amounts above their water use permit (WUP). SWFWMD sees them as a way to reduce groundwater pumping from the aquifer.
The development of surface water and tailwater recovery reservoirs are effective BMPs to achieve both water quality improvements and groundwater conservation. These reservoirs are typically excavated below ground level at the low end of a farm to collect excess irrigation water and storm water run-off. The use of these reservoirs for irrigation is effective in reducing or “offsetting” the amount of groundwater that is withdrawn from the Upper Floridan aquifer for irrigation and frost/freeze protection. They also improve water quality of the downstream watershed by reducing irrigation runoff of mineralized groundwater applied to crops.
To incentivize implementation of farm ponds as a source of irrigation water, the FARMS Program and the producer share the total project costs of the components and materials used in the construction of pump stations that withdraw water from the reservoir and feed it into the irrigation system. This includes, but may not be limited to: surface water pumps; power units for the pump; materials for the foundation and protective structure; filtration systems, fuel tanks, and flow meters; culverts and control structures that enhance tailwater recovery; intake/mainline piping and any other necessary appurtenances to connect the surface water pump station to the existing irrigation system. Although excavation of the reservoir itself is not considered a FARMS eligible cost, it can be included in the total project cost and go towards the grower’s required contribution.
Before the new farm pond is operational the grower will need to modify hisher Water Use Permit to include the new surface withdrawal. The amount of water that is withdrawn from the pond is identified on the Water Use Permit as a surface withdrawal and those same quantities will be shown as stand-by on the new permit.
First let’s use an example of a nursery that is permitted for ten acres, puts in a one acre pond. For starters, the nursery now has nine acres of production, so the WUP is decreased by one acre since there are only nine acres of production land. So the total quantity allocated to the farm is lowered. Some of the water that was allocated on the WUP will be taken off the ground water and moved to the surface water of the pond and that same quantity will be a standby quantity on the ground well should the pond go dry. Let’s just say that is 10% for example sake. So your total allocation must be met with surface water first and then ground water secondly. If your surface water supplies more than the 10%, you can pump from the surface water and reduce the groundwater pumping, however, you still cannot exceed your total WUP (surface + ground cannot be greater than 100%) allocated to the 9 acres. This is where growers find difficulty. If you supplied half of your WUP with your surface water you cannot pump the 90% allocated on your permit from the groundwater. You would be exceeding your total WUP (50% surface and 90% goundwater= 140% of total WUP).
Always read and ask questions about your WUP before you sign it to eliminate conflicts down the road. Ponds may work well when there is too much pressure on ground water resources in an area or if there are issues with ground water quality but may take out potentially productive land. District staff are available to assist any grower with questions/concerns about the use of alternative water supply projects
Growers are encouraged to contact
Hydrogeologist, FARMS Program
(941) 377 – 3722, ext. 6546.