El Dorado County Environmental Health Manager Barbara Houghton said Tuesday the 86-foot Sierra Rose is sealed, but inspectors will monitor efforts to pull it out of the Tahoe Keys Marina, just in case.
The yacht apparently started sinking slowly Sunday night and had reached the marina bottom by Monday morning, though the top floor remained above water Tuesday.
It's not clear what caused the boat to sink, but neighbors reported hearing the sound of tearing metal Sunday night. Witness Heather Contreras tells the Tahoe Daily Tribune more than a dozen people were on the vessel at the time but everyone made it off.
The Reno Gazette-Journal reports a big-screen TV, leather couches and floating slices of bread were visible inside the partially submerged yacht.