Asa Hawley built a small skiff in the summer 1856. Snowshoe Thompson and James Green rowed along the shoreline of Lake Tahoe while Asa paced off a half mile and calculated their speed.
These first white men to circumnavigate Tahoe determined the circumference to be 150 miles (not 72).
They found the outlet stream, but did not realize it was the head of the Truckee River.