Since the early days of water use in Arizona, our state has regulated surface water and groundwater differently. Surface water is governed by the doctrine of prior appropriation, which means that the first person to divert the water and put it to beneficial use has the senior right to that water. All subsequent water users have a junior right to the water and can only use it so long as there is enough to fulfill all the senior rights first. In order to create the basis of a claim to water, the user must file a statement of claim with the Department of Water Resources.


Groundwater, on the other hand, is governed by the doctrine of reasonable use. If a landowner is willing to invest in the infrastructure it takes to access the water, that user has a right to put the water to beneficial use. Aside from applying for permission to drill the well, a groundwater user doesn’t have an obligation to file any sort of claim with the Department. (Of course, this is completely different if the well in question is located within an Active Management Area or other management structure created by the 1980 Groundwater Management Act, but that’s another consideration entirely.)


As with so much else in Arizona water law, however, the ongoing stream adjudications have blurred the distinction between ground and surface water in a significant way, through the concept of subflow. Subflow is water that flows underground through gravel and sand, but it exists so close to a surface stream that it is actually a part of that surface stream, rather than part of a separate groundwater source. In 1992, the Court decided that subflow can be regulated as surface water, rather than groundwater, meaning that it is subject to the doctrine of prior appropriation. After that decision, wells located near a stream or river that had been presumed for decades to be pumping surface water may now be presumed to be pumping surface water, if the Court determines that they are in the “subflow zone.”


So, what does all that mean? It means that water users who did everything they reasonably could have done to secure their right to use groundwater are now at risk of becoming an extremely junior surface water right holder. It also means that there will be thousands of wells with the same priority date, making it unfeasible for the water Special Master to determine a fair way to enforce the well priority system in the first place. And all because they did not, and could not, have known that their well was actually a surface water diversion. 


That doesn’t make a whole lot of sense to us.


If the Court is going to consider subflow as surface water, then we need to find a way to make sure the right to use that water is protected. After all, if well owners had known that they were drilling close enough to the river to be pumping surface water, they would have had a reason to protect their water by filing a claim of right at the Department. But even now, there’s no way to know whether a well is in a subflow zone until the Court draws those lines. This level of uncertainty will only contribute to the ongoing confusion that is the stream adjudications.


That’s why one of our 2020 policy priorities are creating an orderly system of priority for wells that are adjudicated to exist within a subflow zone. While the legislation we proposed this session ended up stalled in the House of Representatives, we are still counting the effort as successful because of the broad group of stakeholders that have come to the table in an effort to help. Thanks to the fact that our members were bold enough to recommend legislation, we have placed agriculture squarely in the driver’s seat for ongoing conversations about the best way to deal with subflow wells. And while we don’t agree on everything, one thing that each of the stakeholder groups wants is certainty for the communities, business, and families that rely on their wells.


Editor’s Note To learn more about how this issue is progressing, be sure and sign up for “While You Were Working,” the weekly Arizona Farm Bureau legislative update. Go to , click on “Public Policy,” and sign up under the Action Center. 


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