Arizona House bill by Rep. Dunn passes, amending irrigation grandfathered rights provisions

Passed bill authored by State Rep. Timothy “Tim” Dunn aims to amend statutes governing irrigation grandfathered rights, allowing owners to transfer associated water duties and requiring notification to the director for oversight, according to the Arizona State Senate.

It passed both chambers as of May 5, clearing the House by a vote of 32-25 and the Senate by a vote of 16-11.

The bill, introduced as SB1518 on Feb. 3, during the first regular session of the 57th Legislature, was formally listed with the short title: ‘subsequent AMAs; groundwater portability’.

The following is our breakdown, based on the actual bill text, and may include interpretation to clarify its provisions.

In essence, this bill amends the Arizona Revised Statutes to add provisions related to irrigation grandfathered rights within subsequent active management areas. It allows owners of these rights to use, sell, transfer or lease both the irrigation rights and the associated water duty tied to specific acres, even if they choose not to irrigate those acres themselves. These associated water duties can be reallocated within the same management area and further transferred by new recipients. The bill mandates that owners notify the director of any such transactions and provide details on the intended use of the water. The director is tasked with establishing rules to implement these changes, including developing flexibility accounts or similar accounting methods.

In the House, 32 Republicans voted in favor while 25 Democrats opposed it.

Meanwhile, in the Senate, 16 Republicans voted in favor while 11 Democrats voted against it.

Dunn introduced the bill in the Arizona Senate on Feb. 3 during the first regular session of the 57th Legislature.

Dunn graduated from the University of Arizona in 1989 with a BS.

Timothy Dunn is currently serving in the Arizona State Senate, representing the state’s 25th Senate District. He replaced previous state senator Sine Kerr in 2025.

The bill was vetoed by Gov. Katie Hobbs on May 12.

In Arizona, the legislative process begins when a bill is introduced in either the House of Representatives or the Senate. It is then assigned to one or more committees for discussion and possible amendment. If approved by committee, the bill proceeds to floor debate and voting in both chambers. If both chambers pass the bill, it is sent to the governor, who may sign it into law, veto it, or allow it to become law without a signature. The Arizona Legislature convenes annually in regular session starting the second Monday in January. Lawmakers introduce hundreds of bills each session, though only a portion make it into law. You can learn more about the legislative process on the Arizona State Legislature website.