Crews working to replace a three-mile stretch of Incline Village General Improvement District's effluent pipeline hit the existing sewer line, causing a sewer spill afternoon.
The spill occurred at 2 p.m. Wednesday one mile south of Incline Village near Sand Harbor.
Crews from Kings Beach-based Burdick Excavating stopped work immediately, but a "minor" amount of treated sewage filled the sewer line trench and overflowed into Lake Tahoe, IVGID officials said.
"We mobilized right away and it took about 30 to 40 minutes before all the flow was shut down," said Utility Superintendent Harvey Johnson. "We immediately shut down the pumps at both ends of the line but unfortunately we couldn't prevent it from filling the trench and reaching the lake."
Unlike last summer's raw sewage spill in Kings Beach, Wednesday's spill involved treated sewage that had been disinfected and chlorinated, said improvement district resource conservationist Sarah Tone.
"This is a lot different than that spill," she said. "At this time we're still calculating the exact numbers, but we've sampled the lake every day and we'll continue to monitor to see exactly what's going on."
Tone said the district had vacuum cleanup trucks on site within 10 minutes.
"We had procedures in place for an event like this," said Dan St. John, public works director for the district. "We initiated the planned reaction and fortunately suffered little damage."
It took construction crews until 10 p.m. Wednesday to repair the leak, and construction resumed early Thursday morning, said Burdick Excavating owner Linda Burdick.
"IVGID had all the repair couplings on hand and we had our best guys there until it was fixed," she said.
Nevada Department of Environmental Protection enforcement and compliance officer David McNeil said he was relieved to hear treated sewage spilled as opposed to raw sewage. The spill didn't occur near any public water intakes or beaches so there is no immediate public health risk, he said.
Environmental officials are working with general-improvement district to assess the damage and disinfect the trench and sewage flow path.