CASA GRANDE — Local water stakeholders got an update on plans for a separate and more detailed groundwater model for parts of Pinal County Wednesday morning from the Pinal Partnership organization.
The Eloy and Maricopa-Stanfield Basin model is being created by a collaboration between Pinal Partnership, the U.S. Bureau of Reclamation, Central Arizona Project, Arizona Department of Water Resources, Pinal County, Pinal County Water Augmentation Authority and several cities, local water companies and irrigation and drainage districts.
Work on collecting and analyzing data for the groundwater model started in November 2018. It will take approximately a year to finish the model, said Valerie Swick from the Bureau of Reclamation.
The model doesn’t cover the entire county or even the entire Pinal Active Management Area, which is a state entity that covers much of the county. The model only covers the Eloy and Maricopa-Stanfield sub-basins in the county, she said. Those basins cover most but not all of the major cities in the county.
Once the model is finished, the group will be able to use it to test multiple water supply and demand scenarios and create plans to meet the needs of those scenarios. The cost of the $1.3 million study will be split between the Bureau of Reclamation, Pinal Partnership and the other study partners. Most of the local costs will be covered by in-kind work provided by CAP, ADWR and others.
The Eloy and Maricopa-Stanfield model is different from the groundwater model for the Pinal Active Management Area that was released by the Arizona Department of Water Resources last year, said Austin Carey from the Central Arizona Project. The Eloy and Maricopa-Stanfield Basin model is designed to look at only the next 43 years of water use from 2018 to 2060. The Arizona Department of Water Resources groundwater model looks at water uses and supply for the next 100 years.
The Eloy and Maricopa-Stanfield Basin model is being created for planning purposes rather than regulatory purposes like ADWR’s Pinal AMA groundwater model, Carey said. The Eloy and Maricopa-Stanfield model will also allow the group to test for multiple possible outcomes and estimate the cost for possible solutions to those outcomes, instead of just providing one outcome like ADWR’s model. The Eloy and Maricopa-Stanfield model is also using historic and current water use data from local irrigation districts and water companies instead of basing the model on what various water users are allocated to use by the state.
The group will be testing five possible scenarios once the groundwater model is finished, he said. Those scenarios include the effects of a hotter, drier climate, more intense urban development, changes in agricultural uses and groundwater pumping on water supplies.
Because the group is still collecting and looking at the data, preliminary results are not available, Carey said. The hope is that the Eloy and Maricopa-Stanfield model will give local stakeholders a better understanding of what the aquifers look like, how they work and allow the area to come up with a sustainable plan for the future.
The group plans to hold the next stakeholder meeting a year from now when the groundwater model is expected to be finished. A subcommittee meeting for the group is scheduled for 1 p.m. Feb. 11 at the Casa Grande Community Recreation Center.