The CHP’s Clear Lake Area office said the wreck occurred at 12:10 p.m. Sunday on Highway 20 east of Harvey Boulevard.
Michael Weschke, 38, of Fortuna was driving a 2013 Kenworth semi truck hauling a 2008 tank trailer westbound in the course of his employment with Steve Will's Trucking & Logging, the CHP said. The trailer was loaded with approximately 6,000 gallons of milk.
As Weschke was nearing Harvey Boulevard, the tractor/trailer overturned on the roadway. The CHP said the trailer separated from the truck, left the roadway and entered Clear Lake.
The CHP said the trailer's tank ruptured and released an undetermined amount of milk into the lake.
Swift actions on behalf of Northshore Fire Protection District personnel prevented the release of any other hazardous materials into the lake, the CHP said.
The CHP said Weschke, who was wearing his seat belt, suffered major injuries and was transported by air ambulance to Santa Rosa Memorial Hospital.
Driving under the influence is not believed to be a factor in this collision, the CHP said.
The roadway was reported to be closed temporarily while cleanup and removal took place.
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