Massive Rock rolls into settling basin at TD water treatment plant

The massive rock that rolled down the hill above the City of The Dalles Wicks Water Treatment plant on around 6 a.m. on Wednesday, Dec. 17. Photo courtesy City of The Dalles

The Dalles, Ore., Dec. 17, 2025 — A large boulder weighing tons broke loose from a hillside above the Wick’s Water Treatment Facility early Wednesday morning, rolling between two buildings before crashing into a concrete settling basin amid the chaos of a freak windstorm that swept through The Dalles.

No one was injured. But it added to the chaos of an already hectic night that saw a freak windstorm bringing immense gusts, one so big it blew a portion of the roof of a medical building neat The Dalles Bridge.

The City of The Dalles said the rock came from a small slide that occurred about 500 feet in elevation above the treatment plant, which is located on Mill Creek Road. As the boulder traveled downslope, it knocked down several trees before reaching the edge of the sediment basin near the compressor building. The rock was slowed before causing significant damage to the basin, city officials said.

Minor damage was reported to a walkway and railing.

City staff were on site Wednesday to assess the damage and evaluate hillside conditions. A senior engineer with experience in rock slope stability and rockfall analysis from Shannon & Wilson, Inc. visited the site Thursday morning to conduct a formal analysis and is expected to provide recommendations on securing the area of the rockfall.

City officials said the incident did not impact operations at the water treatment facility. As a precaution, buildings located directly below the hillside are being kept unoccupied, though the facility remains fully operational and continues normal water treatment functions.

In the unlikely event of a temporary disruption, the city said it has adequate water supply available through the operation of its wells.

The city said it will continue to monitor conditions at the site and provide updates as additional information becomes available.