Water Well Journal
Issue link: https://read.dmtmag.com/i/681918
A small but positive piece of news broke in May regarding California's 4-year-old drought. Less than 90% of the state is in drought for the first time in three years, reported the U.S. Drought Monitor, a federal website that tracks dry conditions. The drop may not sound like much, but any amount of drought relief is welcomed by the state's 38 million residents complying with water restrictions. El Niño is largely the reason for the drop as it typically brings wetter conditions to the West Coast. Aside from this encouraging news, groundwater levels in many wells in California's Central Valley were at or below historical low levels in 2015, according to the U.S. Geological Survey. In addition, from 2007 through 2015, land subsidence that correlates to areas with large groundwater-level declines increased significantly in two large agricultural areas near the towns of El Nido and Pixley. The Turlock Subbasin underlies the San Joaquin River in the San Joaquin Valley of central California, one of the largest aquifers in the western United States. The San Joaquin Valley is one of the most productive agricultural regions in the na- tion. Over time, overpumping has caused groundwater-level declines and associated aquifer-system compaction and land subsidence—resulting in permanent aquifer-system storage loss in the San Joaquin Valley, according to the USGS. In this final part of Water Well Journal's three-part series examining major aquifers in the United States, we look at the Turlock Subbasin and San Joaquin Valley. ● ● ● The Turlock is a subbasin (542 total square miles) of the San Joaquin Valley groundwater basin which occupies about 13,700 total square miles, making it the largest groundwater basin in California. Located between the Tuolumne and Merced Rivers, the Turlock is bounded on the west by the San Joaquin River and on the east by crystalline basement rock of the Sierra Nevada foothills. Runoff from snowmelt and rainfall in the Tuolumne River basin plays a significant role in irrigation and domestic water supply for Turlock and Modesto Irrigation Districts, and water supplied to the city of Turlock is solely groundwater from 150-600 feet below the ground. The primary hydrogeologic units in the Turlock include both consolidated and unconsolidated sedimentary deposits. The consolidated deposits include the Ione Formation of Miocene age, the Valley Springs Formation of Eocene age, and the Mehrten Formation, which was deposited during the Miocene to Pliocene Epochs. Unconsolidated deposits include continental deposits, older alluvium, younger alluvium, and flood-basin deposits. Lacustrine and marsh deposits, which constitute the Corcoran or E-clay aquitard, underlie the west- ern half of the subbasin. The San Joaquin Valley represents the southern two-thirds portion of the Central Valley, which is home to the world's largest swath of ultra-fertile Class 1 soil. The 6.3 million acres of farmland produce more than 350 crops—from fruits and vegetables to nuts and cotton—representing 25% of the food for the United States. Drilling Challenges Steve Arthur's Fresno-based drilling company has stayed busy the last three to four years, driven by the drought condi- tions and a host of other factors promoting short-term con- sumption over long-term survival. But business slowed in May due to farmers determining their upcoming crop plans. It didn't help prices for such crops like milk, almonds, pistachios, and raisins were down. Ironically, the main drilling challenge currently resides above ground for Arthur & Orum Well Drilling Inc., which drills from Bakersfield to Merced. The drought has led to an influx of drillers coming into the state, and Steve says "drought chasers" have slashed prices dramatically to stay afloat. Jobs which once paid $50 to $60 a foot are now $30 a foot. Steve drops his prices to compete with the competition, with his overall estimates running a couple of thousand dol- lars higher than his competition. The market, according to Steve, has been devastated by in- experienced drillers using nontraditional water well drilling equipment and non-water well approved casing. Some are drilling under another state well drilling contractor license number. The goal of these drillers is to drill a well as quick as TURLOCK AND SAN JOAQUIN continues on page 30 (Left) Arthur & Orum Well Drilling Inc. drills a 600-foot well with 17.4-inch plastic well casing in January 2016 for Nunes Dairy in Tulare County, California, using a GEFCO JED-A reverse circulation rig. The well was designed to pump 2500 gallons per minute and the drilling formations were sand and clay. Tulare is located in the heart of the Central Valley. Part three of three: The Turlock Subbasin and San Joaquin Valley By Mike Price Aquifers in the United States WWJ June 2016 29 Twitter @WaterWellJournl