CASA GRANDE — After a wait of several years, the new groundwater model for Pinal County has been posted to the Arizona Department of Water Resources website.
The model shows that the county has insufficient water resources to meet its existing demands and the assured water supply certificates that have been issued for the county for the next 100 years, ADWR Director Thomas Buschatzke told the Arizona House of Representatives Ad-Hoc Committee on Groundwater Supply in Pinal County Friday.
The committee held its second meeting at Casa Grande City Hall Friday in order to allow residents, industry, farmers and water companies to attend.
“We did make some improvements in the (calculation of the) model but we still have unmet demand,” Buschatzke said.
That unmet demand equals more than 8 million acre-feet of water, he said.
The total demand on Pinal County’s groundwater resources for the next 100 years, including future demands reserved through assured water supply analysis, certificates and designations, is more than 80 million acre-feet, Buschatzke said.
The biggest user of groundwater in the Pinal Active Management Area is agriculture, which makes up 60% of the total demand, followed by industry at 3% and municipal sources at 2%, he said.
An acre-foot of water equals about 325,851 gallons, according to the U.S. Geological Survey. The average person uses 80 to 100 gallons of water per day.
Buschatzke pointed out that the model assumes that all water users are withdrawing their maximum allotment of water from the first day they are approved and every day after. In reality, this may not be the case, as the needs for water users, such as agriculture, can vary greatly from day to day and year to year.
The model also doesn’t take into account the amount of treated wastewater that might be recycled or groundwater replenishment programs, because there wasn’t enough data available, he said. Even if the department had the data, the amount of water reused or replenished probably wouldn’t make that much of a difference.
Buschatzke said the department plans to hold a meeting to formally present the model to applicants and other stakeholders in Pinal County during the last week of October. The details of when and where the meeting will take place have not been set yet, he said. However, the department wants the solution to Pinal County’s water issues to come from local stakeholders. The department will then give those solutions to the governor and the Arizona Legislature.