25 MARCH 2025 WorldWide Drilling Resource® Scientists Discover Massive Aquifer in Oregon Adapted from Information by the University of Oregon Scientists from the University of Oregon (UO) and their partners claim Oregon’s Cascade Range mountains contain a precious resource - groundwater. The team mapped the amount of water stored beneath volcanic rocks at the crest of the central Oregon Cascades and found an aquifer much larger than anyone anticipated - nearly three times the maximum capacity of Lake Mead and more than half the volume of Lake Tahoe. The findings may change the way scientists and policymakers think about water in the region - an increasingly urgent issue across the Western United States. It could also influence our understanding of volcanic hazards in the area. When magma interacts with a lot of water, it often leads to explosive eruptions blasting ash and gas into the air, rather than eruptions with slower-moving lava flows. “It is a continental-size lake stored in the rocks at the top of the mountains, like a big water tower,” said Leif Karlstrom, a UO earth scientist who led the study alongside collaborators from Oregon State University, Fort Lewis College, Duke University, the University of Wisconsin, the U.S. Forest Service, and the U.S. Geological Survey. Most Oregonians rely on water originating from the Cascades. However, the discovery of this underground aquifer’s size was a surprise. “We initially set out to better understand how the Cascade landscape has evolved over time, and how water moves through it,” said study coauthor Gordon Grant, a geologist with the Forest Service. “But in conducting this basic research, we discovered . . . the incredible volume of water in active storage in the Cascades and also how the movement of water and the hazards posed by volcanoes are linked together.” Previous estimates of water availability in the Cascades took the areas springs at face value, measuring river and stream discharge. Instead, Karlstrom and his colleagues went deeper - much deeper. Using data from geothermal exploration efforts from the 1980s and 1990s, the team was able to gain a better understanding of the flow of water through different volcanic zones. Normally, rocks get hotter as you drill deeper, but water percolating downward disrupts the temperature gradient, making rocks roughly 3200 feet underground the same temperature as rocks at the surface. By analyzing where the temperature started to pick up again in these boreholes, Karlstrom and his colleagues were able to determine how deeply groundwater was infiltrating through cracks in the volcanic rocks, allowing them to map the volume of the aquifer. Since the boreholes weren’t originally drilled with the intent of mapping groundwater, the actual size and volume of the new aquifer could be even larger. “It is a big, active groundwater reservoir up there right now, but its longevity and resilience to change is set by the availability of recharging waters,” Karlstrom said. The aquifer is largely replenished by snow, so future weather conditions may impact the amount of recharge feeding the high Cascade aquifer. WTR
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