Evidence of older lake bed deposits suggest that Spring Valley was once inundated by a lake during the middle Pliocene and early Pleistocene when the climate may have been much wetter than today. Spring Valley State Park is located 18 miles northeast of Pioche on State Route 322. The elevation of the reservoir is 5,836'. The climate of the area is arid, with hot summers and cold winters. Summer temperatures range from 85 F at midday to 45 F at night.
Rainfall is variable and thunderstorms are common.
Although open year-round, visitors should be aware of colder winter temperatures and snow. Eagle Valley Reservoir is the primary attraction at Spring Valley State Park. Rainbow trout is the primary species. A boat launch is located on the south shore of the reservoir adjacent to the Day Use Picnic Area. A ramp, dock and temporary docking slips are available.