Tifton Georgia Florida Gulf of Mexico Atlanta Athens Irrigation Association Anaheim Revisiting Farm Ponds for Irrigation Water Supply in the Southeast US presented by: Jim Hook, Shane Conger, and Kerry Harrison National Environmentally Sound Production Agriculture Laboratory The University of Georgia, Tifton Campus

Assessment of man-made ponds  As State and Federal Governments begin to look stream flow for withdrawal and discharge permitting  As they examine threatened habitats and species  As ground water level decline Agricultural Irrigation  Ponds as <As alternative to direct stream withdrawals during dry periods that trigger irrigation <As alternative to GW withdrawals from aquifers that sustain base flow <As alternative to GW withdrawals that lower heads in areas with long term decline (confined aquifers)

Ponds supply water for irrigation on Coastal Plain Farms  Early irrigation in Georgia <Tobacco, vegetables, and various supplemental irrigation <Mostly applied by portable and temporary irrigation <Water supplies from the streams flowing through and along their property, but because many of these streams dried during growing season they turned to ponds <Ponds among earliest irrigation water sources.

Man-made Ponds on Georgia Farms  For more than 75 years, farm ponds promoted by USDA Natural Resources Conservation Service (formerly SCS) <Integral part of farm conservation plans <Livestock water security 6 Recreation, fish production, fire protection <Approval & engineering design by SCS/NRCS; 6 construction supervision and approval; <Often cost shared (ASCS/FSA)

Irrigated Area CES Irrigation Surveys 1970 to 2004

Location of agricultural withdrawal permits. The majority of agricultural irrigation areas.

Assessment of Farm Ponds Quantity and their hydrologic significance The Study Area: South Georgia HUC08 (Sub-basins)

Irrigation Water Sources CES Irrigation Surveys 1970 to 2004 Despite growth in irrigation, numbers fed by surface water sources remained constant. Much of growth come from groundwater sources. Surface water includes ponds and streams.

The Floridan aquifer underlies most of the SE Coastal Plains in Georgia and Florida and is their most important source of water.

Agriculture is biggest user of Floridan aquifer water. Growing pressure on ag to reduce withdrawals

In recharge areas the aquifer is resilient and rebounds every year from pumping and natural drainage.

USGS NHD Waterbodies

Ga DOT 2003 Waterbodies

Water Bodies in the Coastal Plain Landscape  Man-made ponds and reservoirs 6 Lake/Ponds – 81,000; 6 Range < 1 to 800 ac 6 Median – 1.2 ac; mean ac 6 Total area lake/ponds – 225,000 ac <GA DOT 2003 Waterbodies So. Ga. HUC08’s

Candler Co DOT mapped ponds

Transects to characterize a sample of study area ponds Random vectors 140 transects mi long 1000 ft wide

Assessment of man-made ponds  Transect Results <Data results: Ponds size 0.25 to 220 ac <Average size of all visible ponds was 11 ac; median 5 ac <

Assessment of man-made ponds  Transects <Pond Clusters: distance to upstream and downstream ponds 6 30% had nearby upstream pond –Half within 0.25 mi 6 50% had nearby downstream pond –Half within 0.25 mi

Assessment of man-made ponds  Catchment areas – small to medium <Mean 350 ac; <Median 200 ac 6 Range 160 ac to 16,000 ac <With the average size pond and average size catchment area, it requires 2.0 in runoff to fill if empty 6 Range 0.1 in to 10 in

Assessment of man-made ponds  Proximity and Use for irrigation <83% within 0.25 mi of farm field <64% adjacent to farm field <25% had existing pump or permitted withdrawal present <Within Ga, 12,700 permits for ag water withdrawal from ponds

Study area with existing Surface Water Permits

Reliability of Farm Water Supply  Quantity of stored water <Assume ratio of mapped to unmapped NHD and relative sizes, there are 6 9,500 farm ponds in South Georgia having average area of 11 ac 6 At average depth of only 5 ft these store 530,000 ac-ft <Relative to irrigation in Georgia 6 With a typical to high annual consumption of 1 ac-ft/ac, this would supply 1/3 to ½ of all irrigated acreage in Georgia without in-season resupply

Reliability of Farm Water Supply  Capability of average sized ponds for center pivots <An average sized center pivot in Georgia is 100 ac <To supply 1 acre-ft/year, a pond would have to provide 100 acre-ft. <Without in-season refill this is a 10 acre pond with and average depth of 10 ft <This is more than twice the capacity of average ponds measured thus far <Considerable cleanout and expansion needed for more dependable pivot supplies

Irrigation Density

Pond Density

For existing ponds and irrigation Capability to meet irrigation demand

Reliability of Farm Water Supply  Conclusions <Existing and refined GIS data show that man-made ponds are numerous and widespread. <Many are too small or too remote from farm fields to serve as reliable irrigation supplies. Still there are at least 10 thousand suitable for irrigation supply. <Expansion and cleanout efforts on existing ponds could substantially increase water security for irrigated farmers and lower dependence on groundwater