Complications of ‘New’ Deep Groundwater
Californians living through a fifth year of historic drought received what seemed like a bit of good news last month: Researchers at Stanford found significantly larger-than-expected groundwater supplies 1,000 to 3,500ft (300 to 1,000m) below the state’s surface, in a first ever assessment of water supplies in California’s deep underground aquifers.
Updated estimates of our precious groundwater supplies are much-needed progress, as some estimates date back to 1989, but it’s critically important to approach these findings with a 21st-century mindset.
Finding massive water reserves deep below California will not return us to the days when we could heedlessly water lawns throughout a scorching summer. The fact of the matter is, it may never make sense to tap these “reserves.”
Rather than dig expensive wells to draw water to the surface, we need to focus on the highly effective and extremely cost-efficient solutions already within reach to make the best use of the water we have.
Between the misleading headlines about the newly found water supplies (for instance, “Drought-Hit California Has a Bonanza of Water – Underground,” reports Time) and recent actions by the state, the average Californian could get the sense that everything is OK in our water-stressed state. This spring, the State Water Resources Control Board and Governor Jerry Brown sent mixed messages about the state of our water crisis by eliminating mandatory water-conservation targets for local water districts, while at the same time making some of the emergency water conservation measures enacted last year permanent.
Since the mandatory water-conservation requirements were eliminated, many water utilities across the state have taken steps that ignore the long-term water shortages we face: Nine of the top 10 utilities in the state have set their water-conservation goals to zero!
To be sure, it is good news that there may be significantly more water underneath California. Using data from the oil and gas industry to measure shallow and deep groundwater sources in eight Central Valley counties, the study found that usable groundwater in the Central Valley may be nearly three times the current estimates. And adding in the moderately salty groundwater deepest in the earth quadruples our current estimates.
But we need to ask ourselves: Will this ever be a truly sustainable water supply? First and foremost, the cost of pumping the water would be prohibitively expensive and energy-intensive. In 2014, with the drought searing the state, National Geographic profiled a Central Valley well-drilling operation that dug ever deeper to reach its customers’ groundwater supplies. A 1,000ft-deep well cost $300,000 to $350,000 to drill, test and fit with pumps. Drilling 2,000ft (600m) farther down would cost an additional $450,000, bringing the total cost for a well that could reach most of the lowest groundwater reserves to $750,000 or more per well. And that doesn’t even include the energy costs.
If that expense doesn’t make you think twice, consider the additional cost to treat this salty groundwater. According to Circle of Blue, “even the moderately salty water can be turned fresh” once it’s pumped to the surface, at a cost of “one-half to two-thirds the energy as removing the salt from seawater.” As Juliet Christian-Smith of the Union of Concerned Scientists notes in the LA Times, even with lesser desalination costs, farmers would still pay exponentially more for that water than the $31 to $174 per acre-foot of water they paid this year.
Beyond the cost considerations, it’s important to manage the state’s groundwater and surface water as one system. Rushing in to withdraw these new resources would lead to even more drastic land subsidence than we’re already seeing, such as in some parts of the San Joaquin Valley that are dropping as much as 2in (5cm) per month and could potentially impact stream flow.
Water conservation and efficiency are our best tools to save water immediately, starting with fixing leaks. At the Silicon Valley Leadership Group’s 2016 Summit last month, Tim Anderson, from the Sonoma County Water Agency, explained how leak detection can save huge amounts of water. One of the agency’s small municipal customers uncovered a leak that released approximately 100,000 gallons (380,000 liters) of water per day – nearly one-third of the customer’s total supply production! Senate bill 555, signed by the governor last fall, requires all urban water suppliers to conduct surveys of their water losses and publicly report that data, with the goal of finding and eliminating water leaks like that in Sonoma County.
Water recycling is another method that makes better use of our scarce water resources, and one that the state should require water agencies to pursue. Senate bill 163, which stalled in the state Senate a few weeks ago, would have declared discharging treated wastewater to coastal waters a “waste and unreasonable use” of water resources, and thus required water agencies to recycle their wastewater. While water recycling has energy costs, a 2013 reportfrom the Pacific Institute found the costs were significantly lower than either desalinating seawater or transporting water from Northern to Southern California.
Similarly, we should capture stormwater both for use and to recharge groundwater basins. The city of Los Angeles is looking to transform its 2,000 acres (800 hectares) of alleyways to capture stormwater, for example.
In many ways, California’s leaders understand the scale of the water crisis we face and are acting to address it – but now we need them to convey the urgency of the crisis consistently to the public. That includes pursuing readily available, cost-effective water resources before turning to deep underground reserves.