Griswold Number 1 Reservoir is a reservoir located in Niobrara County, Wyoming. It appears on the Oat Creek NW USGS 7.5-minute topographic quadrangle. The elevation at this location is approximately 4,210.61 feet (1,283.39 m) above sea level. The nearest populated place is Redbird, approximately 6.9 miles to the WNW.