This editorial is from the November issue of M&A’s Arizona Water Policy Update.
What is Arizona’s next bucket of water? Southern California may provide some clues.
The major population centers in southern California have scant precipitation and are located adjacent to the Pacific Ocean, within relatively small drainage basins overlying equally small aquifers. Southern California has very limited supplies of fresh groundwater and relies almost entirely on imported water supplies — water that must be conveyed hundreds of miles from the Colorado River and northern California via the State Water Project. Because of concerns about delivery costs and reliability of imported water supplies, the area has traditionally focused on reclaimed water (treated effluent) and desalinated ocean water as the “next buckets” of water. However, problems with public perception, environmental impacts, and escalating costs have led to delays in implementing large desalination and water recycling projects — as illustrated most recently by Carlsbad’s 10-year-and-counting trek through the gauntlet of permits and lawsuits. In response to these challenges, recent efforts in southern California are focusing on local groundwater supplies that were previously overlooked because impaired water quality and other technical challenges made them too expensive to develop. For example, the USGS has spent the last decade working with the City of San Diego to develop a network of monitoring wells to characterize the hydrogeology and water quality of the deep coastal aquifer in the San Diego area. The mostly brackish groundwater in this deep aquifer is being targeted as a potential future supply source. Understanding that treatment costs need to be considered for any new water supply, San Diego is betting that local groundwater pumped from greater depths could be a viable component of its portfolio — one that could be both less expensive and more reliable than imported supplies.
Within Arizona, our extensive brackish groundwater supplies may start to look similarly attractive when water planners start looking at the cost of developing new supplies that require advanced treatment and/or conveyance over long distances. Areas around Yuma, Holbrook, Gila Bend, and Willcox have relatively abundant and largely untapped supplies of brackish groundwater. However, unlike in southern California, these aquifers lie far from Arizona’s major population centers, so there will be costs for delivery as well as for pumping and treatment. Water managers and planners must determine if, and how, they can use these supplies in the areas that are thirsty enough to develop them.