Study reveals hidden volcanic aquifer in Oregon Cascades holds 81 km³ water
Researchers analyzing old geothermal temperature logs have estimated that at least 81 cubic kilometres of water are stored in the volcanic rocks of Oregon’s Cascade Range, roughly three times the volume of Lake Mead.
By applying heat-flow models to historic geothermal drill-hole temperature data, scientists from the University of Oregon have uncovered a substantial underground water reservoir in the Oregon Cascade Range. Led by geosciences professor Leif Karlstrom, the researchers compared expected temperature profiles for dry volcanic rock with actual logs, revealing a regionally extensive, water-filled zone. Their calculations indicate at least 81 cubic kilometres of water, nearly three times the full capacity of Lake Mead, the United States’ largest reservoir.
The water is distributed across countless pores, fractures and gas-bubble cavities within lava flows, ash layers and volcanic breccia, forming a three-dimensional sponge rather than a discrete lake. The finding suggests that deep volcanic aquifers may play a larger role in buffering streamflow during droughts and could affect how scientists model volcanic eruption dynamics. The method—using existing geothermal temperature records—offers a low-cost way to assess hidden groundwater in other volcanic regions worldwide. Future work will aim to integrate these estimates with surface hydrology and evaluate climate-change impacts on recharge and storage.
Why it matters
Understanding the hidden groundwater in volcanic mountains can improve water management and volcanic risk assessments.
In this story
