Topaz Lake is a reservoir located on the California-Nevada border, about 75 miles (121 km) south of Reno.

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.

[2] The levee and reservoir have been owned and operated by the Walker River Irrigation District since its construction.