Existing practice: No uniformity test performed in last 5 years.
This proposed practice does not directly save or waste water in itself. However, the modifications to the system to improve uniformity will result in the change in water use.

Water Conserving Practice: Perform Uniformity Test

A uniformity test is a procedure to measure the output and distribution of sprinklers, emitters, etc. to determine whether the amount of water assumed to be reaching the crop is actually reaching the crop. Poor uniformity (less than 80% Christiansen's coefficient of uniformity) implies that a sufficiently large section of the field is not receiving the average water application. As a result, the water that is being applied may be higher in some areas than is expected (encourages deep percolation and runoff) or lower (not meeting water needs). Poor uniformity also reduces the efficiency of water use.

Potential No. of Irrigation System Affected¹	11,700
Estimated Water Savings (%)	0 (?⁴)
Average Year Water Savings (million gal.)²	0
Dry Year Water Savings (million gal.)³	0
Est. Cost of Full Implementation on Avg. System ($, 1998)	$250
Statewide Costs for Full Implementation ($, 1998)	$2,925,000
Cost / Unit of Water Saved in Average Year ($, 1998 /million gal.)	0

Estimated water savings are between -10 and +10 percent if improvements are made. Additional water may be required if uniformity is affected by clogged emitters in a drip system. Water savings may be associated with worn sprinklers with larger orifices than in the original new sprinkler. On the average, water savings are about 0%, but water will be used more efficiently. For many situations where farmers use the crop condition to schedule irrigations, water savings will be higher if the farmer has been irrigating based on the stressed areas.

About 11,700 systems are estimated to be at least 5 years old and have not had a uniformity test in the last 5 years. The average cost for a uniformity test on a 100 acre system is about $250. Obviously, the changes in the system to improve uniformity would have associated costs depending on the system needs.

Although this recommendation does not achieve water savings, the benefits of more efficient water application can be directly tied to improved and/or more consistent crop yields. In addition, the potential for improved water and chemical management can benefit water quality, reduce potential runoff, and reduce potential leaching of nutrients and chemicals.

Source: Evans, R.O., K.A. Harrison, J.E. Hook, C.V. Privette, W.I. Segars, W.B. Smith, D.L. Thomas, and A.W. Tyson. 1998. Irrigation conservation practices appropriate for the Southeastern United States. D.L. Thomas (ed.) Geologic Survey Project Report No. 32. Georgia Geologic Survey, Georgia Department Of Natural Resources, Environmental Protection Division, Atlanta, GA 30334. 43p.