Pyramid Lake is a lake that is replenished each day by how much water it receives from the Truckee River flowing out of Lake Tahoe. The Truckee River fills Pyramid Lake at its southern end. Being sort of land locked Pyramid Lake has no river flowing out. Water can only evaporate or seep thorough its bottom through under ground springs and crevices. The lake draws it name from a series of rocks on one shoreline that look like pyramids and are sacred lands of the the Pyramid Indians who have inhabited the lake and lived off the trout and chub that were indigenous here. Named by John C. Fremont, The lake is part of ancient Lake Lahontan that was formed as the reseeding glaciers in the Pleistocene epoch caused a huge lake that once spread from Salt Lake City to the almost the Pacific Ocean. The world record cutthroat is from Pyramid Lake and was caught in 1925 and weighed 41 lbs. and was 39 inches long.