Photo of an irrigation ditch

How to Calculate Irrigation Efficiency

Are you using too much water to irrigate a crop? Not enough? Here's a simple way to calculate water efficiency using this USDA publication and your irrigation district or pump records. To calculate irrigation efficiency (IE), divide the crop irrigation requirement (obtained from the publication below) by the total water usage recorded by the grower.

Example: If a grower's alfalfa water use is 10 acre-feet per year (10 feet x 12 inch/feet = 120 inches) and the irrigation requirement is 74.3 inches, then the IE is 100 x (74.3/120) = 61.9 percent.

- Extension Irrigation Specialist Diaa Elshikha, Ph.D.

General Information

The program is helping scores of growers across Arizona replace inefficient flood irrigation systems with sprinkler or drip systems that use at least 20 percent less water. It pays growers $1,500 per acre up to $1 million per farm to switch irrigation.

  • Is there an approved vendor for the program? The Water Irrigation Efficiency Program does not have an approved vendor list. Vendor selection is solely at the discretion of the applicant (Grower). Vendors must carry an insurance policy of greater than or equal to $2-million.  Vendor systems must demonstrate at least 20% water efficiency to be eligible for the program.
  • Is cement canal overhaul and repair covered? As long as it is done in part with a new irrigation system. Canal overhaul and repair is not covered on its own.
  • Is labor for installation and more costly removal of drip tape covered? No, the funds should be used to only cover the initial installation of the new irrigation system. Any labor and maintenance will be covered by the applicant.
  • Will the grant pay for irrigation water from the district? No, this grant will only cover new irrigation systems.
  • Will this grant support the drilling of a new well? As long as the well installation is part of a new irrigation system, it can be funded, but it must be done in part with a larger project. Well installation without a new irrigation system will not be covered.
  • Can I apply for this grant in conjunction with applying for other grants? Yes, you can apply for funds from the Water Irrigation Efficiency Program while working on other grants.
  • What are the benchmarks for 50% completion for my project? There are different benchmarks depending on what type of system you are installing. If you are installing a drip system, once the system is installed over 50% of the acres you are applying for, you have achieved the 50% benchmark. If you are installing a sprinkler system, once you have all of the equipment for your project onsite, you have achieved your 50% benchmark.

Steps to Take After Your Application is Approved

  1. Sign and Return Forms - After receiving email confirmation of your approved application, you will receive the following forms via email to complete. Irrigation Efficiency Agreement, FAR form, vendor information form, and W-9. Include all requested information. The University does not need information from your selected irrigation vendor included in these forms. Return the completed forms to Stephanie Brennan.
  2. Purchase Order Information and First Invoice - After you returned completed forms, the University will process your forms and issue a purchase order. You will receive a PO for each separate approved application. Include the PO number with each invoice. The first invoice should be for 50 percent of your PO amount.
  3. Site Visit - To receive the second half of your approved funding, you must complete a site visit with one of our agricultural technicians. Once the project nears 50 completion, schedule a visit by contacting Stephanie Brennan. If you have questions about what 50 percent project completion looks like, please refer to our FAQs, which also include information about what the agricultural technician will examine. You must be present during the site visit. After the technician confirms 50 percent completion, they will sign off and ask for your signature. During your first site visit, your agricultural technician will discuss water tracking requirements with you. If your proposal does not include any type of flow meter, please let your technician know.
  4. Second Invoice - After you receive signed confirmation of 50 percent completion, submit your second invoice for the remainder of approved funding. The submission process is the same as the first invoice.
  5. Finished Installation Site Visit - After your final payment is issued and your installation is complete, schedule a site visit. The technician will help develop a data collection plan to ensure all required data is collected and reported on over the next three years.