It is located approximately 3 miles west of Inchelium on County Highway 2, also known as Bridge Creek Road, at the mouth of a long coulee in rural Seylor Valley. Two prominent summits, Stranger Mountain, 3,021 feet, and Monument Butte, 2,057 feet, overlook Impach less than 2 miles to the south. It is located east of Twin Lakes and north of Meteor, Kewa, and Covada.
The community's place name means "white lake" in the Salishan dialect of the San Poil tribe, probably a reference to Camille Lake located about 1.25 miles north.
Historically, Impach has been the site of traditional Native American dance ceremonies by members of the confederated tribes. Gold was discovered in Ferry County in 1896 and several gold mines operated in the Impach area as late as the 1950s, including the nearby Gold Twenty Mine which produced lode gold, lead, and silver. During the early 1930s, a predecessor of the Works Progress Administration established a small logging operation in Impach, which brought some unemployed families to the area at the height of the Great Depression. The scenic valley is primarily grazing land today.