Lake Tahoe has its own water monster. Washoe and Paiute accounts spoke of a creature in the deep long before the resorts arrived, and generations of boaters have since reported something large moving through a lake that drops past 1,600 feet. Nothing has ever been landed, but "Tessie" remains a fixture of Tahoe folklore.
Lake Tahoe (El Dorado / Placer counties, on the California-Nevada line)
See it on the map