Walker Lake is a remnant of the ancient Lake Lahontan from the Pleistocene era. Lake Lahontan covered most of current-day northern Nevada and extended into parts of current-day California and Oregon. Pyramid Lake, Nevada and Honey Lake, California are other remnants of the ancient Lake Lahontan.
For decades, diversions from the river have sustained a strong agricultural economy but produced an unintended consequence for the lake: dramatically reduced freshwater inflows to Walker Lake. As a result of declining water levels, Total Dissolved Solids (TDS) in Walker Lake has increased dramatically to the point that the lake can no longer support its native fish and wildlife populations.