Current & Planned Water Use
Current Groundwater Use
For residential use, the 2010 Census found 10,669 residents in the Big Chino/Williamson Valleys. At average per capita water use rates, we estimate about 1,800 afy of groundwater is used.
Thus the total current groundwater use is in the range of 4,800 afy to 7,500 afy, reflecting the uncertainty in agricultural usage.
Updated December 19, 2018Planned Uses for Big Chino Water
The 8,067 afy of exemption water will be divided 54/46 between Prescott and Prescott Valley. Prescott has committed 900 afy to the phased expansion of the Deep Well Ranch. Prescott Valley has committed 2,000 afy of their 3,711 afy share of Big Chino exemption water to development on a section of State Trust Lands near the city. Prescott Valley has not committed any exemption water, or the effluent collected from using that water, either to safe yield or to mitigation; presumably PV’s share will be entirely used to support growth and development.
Prescott Council Resolution 3688 states that their share of the HIA water will be dedicated to either safe yield in the AMA or to mitigate the effects of pumping on the Verde River and would not be used for development or growth. Prescott Valley has made no official commitments to use their share of HIA water for safe yield.
Updated December 19, 2018Future Population Growth
Updated December 19, 2018Big Chino Valley Pumped Storage Project
ITC Holding, Inc has applied for a preliminary permit to the Federal Energy Regulatory Commission (FERC) to operate a pumped storage energy facility in the Big Chino Valley, about 6 miles south of Seligman. The project will construct a water storage reservoir high on the slopes of Picacho Butte connected by subsurface pipes to another reservoir on the valley floor.
In operation, the project will use inexpensive off-peak electricity to pump water into the high reservoir, often at night. During peak electricity rates periods, typically summer days, water is released from the upper reservoir into the lower reservoir to generate power for sale at peak rates.
Pumped storage is similar to a battery in that it stores and releases electric energy; the process is roughly 80% efficient. The project intends to profit by using the price spread between off-peak and peak power rates and by other contracted services. Possible sources of off-peak power would be regional coal-fired power plants, photovoltaic power, and wind-generated electricity.
For a more complete description of the project, see the CWAG Info Bulletin.
Updated December 19, 2018Summary of Big Chino Demand
Expanded agricultural irrigation is a huge potential groundwater consumer. There are no state laws restricting new irrigated fields in the Big Chino Valley. One new 1,000 acre alfalfa field could consume 5,000 afy of groundwater. For comparison, in the last decade, agricultural pumping in both Kingman and Wilcox has increased 25,000 afy from out-of-state agribusiness seeking more reliable water supplies than in California. We estimate that expanded irrigation could consume up to 1.6 rivers of water each year!
Legally authorized water exports (includes the Big Chino Water Ranch and Historically Irrigated Acreage water) could consume another 1.6 rivers every year. At this time the total legally exportable water from the Big Chino is 18,813 afy, including the Big Chino Water Ranch and HIA water.
Future groundwater demand from population growth and development in the valley at 1.5% annual population growth could consume up to 20,000 afy, or another 1.6 rivers per year.
The Big Chino Valley Pumped Storage facility will use14,000 afy of groundwater for only two years. The developer intends to mitigate the effects on base flow. If they are successful, there would be very little impact on the river.
Totaling these estimates, legally permitted groundwater demand in the Big Chino could equal FIVE TIMES the current river base flow (now about 13,000 afy).
Updated December 19, 2018