The modern reservoir was formed by diverting waters from the West Walker River into a nearby basin that had previously contained a smaller, natural lake. That lake had historical significance since it lay on the route taken by American explorer Jedediah Smith in late spring of 1827 when leaving California at the end of his first journey, the first crossing ever of the Sierra Nevada by a non-native. Smith came southeast through Monitor Pass, then east past Topaz Lake into Nevada.