Thursday October 06, 2022

Irrigation Allowance Index FAQs

Frequently Asked Questions 

1. Is there a cap on how much water can be applied with the Irrigation Allowance Index?

Answer: Yes, there is an upper limit depending on crop type.  For example, Annual Crops such as citrus and avocado crops have a clear annual cap. In other cases, Main Season Strawberries or Raspberries have a clear cap. Other single crops have clear caps.  In other cases, the cap may not be clear because of the way multiple crops may be combined, and it may initially appear that some crops could be allocated 5, 6, or more acre feet per year.  This is not correct, and in those cases, the cap is set at the Nursery - Greenhouse irrigation allowance values for each zone and year type. 

2. I’m a well operator, but I also purchase water from a mutual water company or other water provider.  With multiple water providers for my crop, who is in charge of filing the Irrigation Allowance Index?

Answer: For parcels with wells, it’s ultimately the responsibility of the land owner to make sure this IAI reporting is done, for this reason the land owner’s well operator should complete this IAI Application.

For other scenarios, it was less clear until recently. In May, the Board approved Resolution No. 2015-02. It establishes Irrigation Allowance Index (IAI) reporting requirements for agricultural well operators including mutual water companies and special districts that primarily supply groundwater to others for agricultural use but are not an end user of groundwater for irrigation. These are considered "Agricultural Providers." If you are not an Agricultural Provider, but an agricultural well operator that receives water from an Agricultural Provider, you are required to include the water from the Agricultural Provider in your IAI Application. If you are not an Agricultural Provider or an agricultural well operator, but a customer of an Agricultural Provider, the Agricultural Provider will need to include information about the crops you grow when it completes the Annual IAI Application. Please contact the Agricultural Provider to determine what information they need from you.

3. Do I really need to send in a map that shows the location of the well(s) and irrigated acres by crop when I submit my Irrigation Allowance Index Application?

Answer: Yes. The irrigated acreage value is a critical component to the Irrigation Allowance Index (IAI) calculation; therefore, it must be quantified and then used in the calculation.

4. I don’t know how to measure my irrigated acreage. What do I do?

Answer: You can use the GIS Mapping Tool to zoom in to your area, create an aerial photo, and measure out the irrigated acreage. The website works similar to Google Maps or Google Earth. We have provided Step-by-Step Instructions under Irrigation Allowance Index Tools.


There is a similar web-based tool used in the year-end IAI filing in the FCGMA Online software application.

5. I don’t know what my Assessor’s Parcel Number (APN) is and I don’t know where to get an Assessor’s Parcel Map. I also don’t know my parcel acreage. What do I do?

Answer: This information is not handled by the FCGMA, but you can locate this information by going to the County of Ventura Assessor’s website If you are still having trouble, please contact us.

6. I have a Pesticide Permit Map from the County of Ventura Agricultural Commissioner. Can I submit this map with my Irrigation Allowance Index Application instead of the Assessor’s Parcel Map?

Answer: Yes. Please make sure the irrigated acreage and well location is clearly indicated on the map. You still must provide your Assessor’s Parcel Number(s) on your application.

7. Do I pick the Year Type?

Answer: No, the FCGMA sets the Year Type after the precipitation data is computed for the period.

8. How am I supposed to estimate the percent crop cover?  Do you have examples?

Answer: Yes, we have examples.

9. The first section on the Irrigation Allowance Index Application asks me to include “ALL” water applied. Why?

Answer: This is because the total water applied is used in the calculation for the Irrigation Allowance Index (IAI). Sometimes all sources of water are not included on the IAI paperwork which causes the result to be incorrect, resulting in our office contacting the well operator to ask them to resubmit the paperwork listing ALL water applied.

10. Your Ordinance Code states that if my IAI value is greater than 1.0, that a surcharge may be assessed.  Can the FCGMA assess a surcharge for all water I used, or only groundwater I extracted?

Answer: The Agency can only assess surcharges on groundwater extracted within the Agency boundaries. (See the Ordiance Code language below for detailed information.)

Section 5.8.5 - Irrigation Allowance Index Surcharge - Facilities relying on the annual efficiency allocation shall also be subject to surcharge for exceeding an IAI of 1.0. Extraction surcharges will be imposed as follows: if the total water applied includes only extractions, surcharges will be imposed on all water used over an IAI of 1.0. If the total water applied includes a blend of extractions and other water, and the total water applied results in an IAI above 1.0, the IAI will be recalculated using only extractions and any surface water delivered through United Water Conservation Districts' Pumping Trough Pipeline, Pleasant Valley Pipeline, or Line C. If the IAI as recalculated exceeds 1.0, the total water applied from those sources will be determined and compared to the extractions. If the extractions are greater than or equal to the water applied above an IAI of 1.0, surcharges will be imposed on the water applied above an IAI of 1.0, surcharges will be imposed on the water applied above an IAI of 1.0. If the extractions are less than the water applied above an IAI of 1.0, surcharges will be imposed on all extractions. 

Section - Notwithstanding an operator's irrigation allowance, extractions from an Agricultural Extraction Facility in excess of the irrigation allowance for "Nursery (Greenhouse)" shall be subject to surcharges.

11. Where did these Irrigation Allowances come from?

Answer: With one exception, the allowances recently adopted by the Board on April 11, 2014 come from Task Reports. The one exception is for the irrigation allowance for the Year-Round Vegetables numbers. This number was developed by FCGMA’s consultant who prepared the earlier task reports.  The FCGMA Board recently reduced the irrigation allowances by 25% (effective August 1, 2014) as part of Emergency Ordinance E.

There are some additional irrigation allowances being developed using standard CIMIS based technical approaches. These include irrigation allowances for artichokes, stone fruit, wine grapes, and mustard. If you have any good crop-specific data on these crops, please feel free to make it available to FCGMA staff.

12. If I grow vegetable crops year round, should I roll up the water allowance for Spring, Summer and Fall Vegetables?

Answer: No. The FCGMA did not intend for those three values to be added together. However, until this question came up, the FCGMA hadn’t put together a maximum value for vegetable growers that farm two or more crops per year. To help clarify this question, the Crop Year Irrigation Allowance table now shows the maximum irrigation allowance for year-round vegetable growers (see the Year-Round Vegetables Crops section).

13. Can I add another crop irrigation allowance to the irrigation allowance for Year-Round Vegetables crop categories under the same acreage?

Answer: No.

14. What water allowances should not be combined for a single year?

Answer: Within a given crop year, if the actual growing periods of crops on the same acreage overlap, then the assumption is they cannot be grown on the same land at the same time. So in that case, the allowances shouldn’t be combined.

15. I’m looking at the Irrigation Allowances and your crop year calendar and I see that my 100 acre Annual crop has an Irrigation Allowance of 3 acre feet per acre, but it is only going to be grown for 6 months this year, and it will be well established after that and fully carry through all 12 months in future years.  Because it's only going to be in the ground half of this year, do I only report half the acres (50) in this crop year?

Answer: No, that is not the right way to do that.  There are a couple problems with that approach: it reports the wrong acres and it won’t match the Assessor’s Parcel Map you provide. These two issues may create questions and require unnecessary follow up for both you and Agency staff. 

The right way to handle this is simply to list the actual acres, but because it’s a partial year, pro-rate the water. This is simple to do on the IAI Application.

16. I intercrop trees throughout the crop year. I have Avocado and Citrus trees intercropped with each other. I don’t know the individual acreage of each crop. How should I report this?

Answer: You will need to choose which tree crop best describes your planted acreage.

17. Some growers keep very detailed records on crop rotations. Is that level of detail necessary for the Irrigation Allowance Index?

Answer: We know some growers keep very detailed records, but we don’t require those be provided with the Irrigation Allowance Index paperwork; however, we are very interested in finding new ways to improve the reporting system that would allow the growers and the FCGMA to better show the efficiency of agricultural water use. If you have a better way, please share it with us.

18. My neighbors needed water and I provided it to them. How am I supposed to report this?

Answer: We are formalizing a process for this type of reporting. In the meantime, please keep careful records and indicate on your Semi-Annual Extraction Statements that some water (include the amount) was delivered elsewhere.

19. I used to get 3 acre feet per acre for my 50 irrigated acres; a total of 150 acre feet per year.  Now that the FCGMA has reduced that allowance by 25%, it only comes out to 2.25 acre feet per acre for my 50 acres; a total of 112.5 acre feet per year.  That’s not enough water for the 50 acres, but would be enough for 45 acres.  Looks like I need to fallow 10% of my acres.  Can I get an irrigation allowance for that fallowed acreage? 

Answer: Yes. Please complete the Fallow or Non-Irrigated Land Allowance Application and submit to the Agency.

20. I grow flowers. What crop category should I use on my Irrigation Allowance Index (IAI) Application?

Answer: Nursery - Non-Greenhouse