Mount Hood Meltwater Pond Grows, Raising Debris Risks

A large meltwater pond near Coalman Glacier is under observation for potential impacts on Highway 35 infrastructure.

Updated on Oct. 30, 2026 in Current Conditions

A high-altitude glacial pond sitting within a rocky, gray volcanic basin on Mount Hood. — The USGS is monitoring an expanded 13-million-gallon meltwater pond at Mount Hood's Coalman Glacier that could trigger debris flows near Highway 35. AI Illustration. Upload story photo >

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On October 6, 2026, a helicopter crew identified an expanded meltwater pond at the base of Mount Hood's Coalman Glacier containing 13 million gallons of water. The USGS issued a formal notice on October 23, 2026, regarding the potential for a debris flow to impact the nearby Highway 35 bridge.

Why it matters

The formation of this pond is linked to extreme weather, specifically record low snow levels during the 2025-2026 winter and an intense summer heat wave. Experts are monitoring the site as the terrain funnels water toward the White River, threatening local infrastructure.

The pond contains roughly 50,000 cubic meters of water with a provisional pH of 4. Mount Hood remains at a normal alert level, though the current accumulation is significantly larger than in prior seasons.

The players

USGS Cascades Volcano Observatory

This federal agency is responsible for monitoring volcanic and geological hazards throughout the Pacific Northwest.

Mount Hood

Located in Oregon, this stratovolcano is the state's highest peak and hosts the Coalman Glacier.

The details

The basin holding the water is hemmed in by Crater Rock, the summit cliffs, and an earthen berm that currently appears stable. If released, the volume could cause a debris flow similar to the 1980 incident on Polallie Creek that resulted in $13 million in damage.

December 25, 1980: A debris flow on Polallie Creek caused significant flood damage.
July 19, 2026: The Palmer Express lift shut down early for the season.
October 6, 2026: A helicopter crew spotted the expanded meltwater pond.
October 23, 2026: The USGS Cascades Volcano Observatory issued a formal notice.

Seasonal Patterns

The current pond formation mirrors historical flood events like the 1980 Polallie Creek debris flow, which serves as a benchmark for potential damage. With Oregon seeing a decline from 36 glaciers in the 1980s to 25 today, the region is experiencing a long-term shift in mountain hydrology.

Residents and travelers should remain alert for official safety advisories issued by the USGS regarding Highway 35 conditions. Monitor local authorities for potential road closures or emergency instructions as the USGS continues its measurement of the pond basin.

The takeaway

The growth of this meltwater pond highlights the increasing volatility of mountain terrain after record-low snowfall. Ongoing USGS monitoring remains critical to understanding how thin snow cover and heat waves impact high-altitude stability.