Only land associated with a Certificate of Irrigation Grandfathered Right (IGFR) can be legally irrigated with groundwater within an AMA. A.R.S. § 45-465. These certificates were issued by the Arizona Department of Water Resources (Department) based on crops and acreage planted from the years 1975 to 1980. Land not irrigated during this time period may not be irrigated unless one of the exceptions stated in the Groundwater Code (Code) applies. A.R.S. § 45-452. For each IGFR, the Department establishes a maximum annual groundwater allotment based on certain statutory criteria.

Non-Indian agriculture is responsible for approximately 80 percent of the total annual water use in the Pinal AMA. In 2001 non-Indian agriculture used 792,300 acre-feet of water, of which 341,400 acre-feet were pumped groundwater, 115,300 acre-feet were in-lieu groundwater, 272,700 acre-feet were Central Arizona Project (CAP) water, 58,400 acre-feet were from other surface water sources (principally the Gila River), and 4,500 acre-feet were effluent.

Third Management Plan Conservation Requirements

For the Third Management Plan (TMP) the Department deferred adoption of a Base Program under A.R.S. § 45-566(A)(1) as part of the Agricultural Conservation Program. The delay was based on concerns that had been raised by the agricultural community regarding the proposed adoption of an agricultural conservation program that included water duties based upon an 85 percent irrigation efficiency.

This issue was resolved in 2002 when the Legislature enacted legislation requiring the Department to calculate the water duties for most farms using an assigned irrigation efficiency of 80 percent. A lower assigned irrigation efficiency may be used for farms determined to have limiting soils or excessive slopes and for farms where orchard crops were historically grown and continue to be grown. The legislation also requires the Department to modify the TMP to include a Best Management Practices (BMP) Program as an alternative to the Base Program. A.R.S. § 45-566.02(F).

In May 2003, the Director adopted modifications to Chapter 4 of the TMP to comply with the legislation enacted in 2002. Chapter 4 has been replaced in its entirety with a new Chapter 4. The new chapter includes the addition of a Base Program with water duties calculated in the manner required by the legislation and the addition of a BMP Program. The new chapter retains the Historic Cropping Program under A.R.S. § 45-566.02 as an alternative program and the conservation requirements for irrigation distribution systems.