Pyramid Lake is the geographic sink of the basin of the Truckee River, 40 mi northeast of Reno, Nevada, United States.
Pyramid Lake is the biggest remnant of ancient Lake Lahontan, the colossal inland sea that once covered most of Nevada. It is approximately 15 miles long and 11 miles wide, covering 112,000 acres entirely enclosed within the Pyramid Lake Paiute Tribe Reservation.
Pyramid Lake is fed by the Truckee River, which is mostly the outflow from Lake Tahoe. The Truckee River enters Pyramid Lake at its southern end. Pyramid Lake is an endorheic lake. It has no outlet, with water leaving only by evaporation, or sub-surface seepage. The lake has about 10% of the area of the Great Salt Lake, but it has about 25% more volume. The salinity is approximately 1/6 that of sea water. Although clear Lake Tahoe forms the headwaters that drain to Pyramid Lake, the Truckee River delivers more turbid waters to Pyramid Lake after traversing the steep Sierra terrain and collecting moderately high silt-loaded surface runoff.
The north and east side of the lake have been restricted to the public and non-Tribal members for nearly a decade.