Historically, ancestors of the Nimiipu (people of the Nez Perce Tribe) were the first inhabitants of this area. While archeologists posit that humans arrived in the Palouse region more than 12,000 years ago (Black, et al., 1997), Nimiipu oral tradition states that they have been here since time immemorial (NPT Strategic Management Plan, 2007). Intensive European settlement of this region followed the discovery of gold and other minerals in the mid 1800’s (Black, et al, 1997). Although the Lapwai Creek watershed falls almost completely within the boundaries of the Nez Perce Reservation, the majority of the land within the watershed is owned by non-Indians.

The Lapwai Creek watershed falls within both Lewis and Nez Perce Counties. The population density of Nez Perce County is strongly influenced by Lewiston, ID, population of over 30,000, which lies outside of the watershed boundary. The population density of Lewis County is approximately 7.8 people per square mile according to US Census data, giving it a rural classification, which better represents the area within the watershed. Major centers of population within the watershed are Lapwai (population 1,134), Culdesac (population 378), and Winchester (population 308); additionally, the communities of Slickpoo, Sweetwater, Spalding and Reubens are located within the watershed, each with a population of 150 or less as of 1990.

The predominant rock type in the Lapwai Creek watershed is the Columbia River basalt group, consisting of a series of extrusive volcanic flows measuring 2,000 to 4,000 feet in thickness. As many as 17 different flows have been counted with each flow ranging from 25 to 150 feet in thickness. Loess deposits blanket the basalt above the escarpment with steep valleys carved through the basalts below. A semi-circular band of granitics representative of the Idaho Batholith extends through the upper portions of the watershed. The granitics are centered around Winchester Lake and extend from the Lapwai Creek headwaters through central Mission Creek and southward along the divide between the headwaters of Sweetwater and Webb Creeks (description from WSU Assessment, 2001).