William Pearce was born on February 1, 1848 in Elgin County, Ontario, the son of John and Elizabeth (nee Moorhouse) Pearce. He received his education in St. Thomas and at the University of Toronto. He married Margaret A. Meyer in 1881. He was engaged on private and railway surveys until 1873, and was in charge of survey parties in Manitoba and the North-West from 1874 to 1881. In 1882 he was appointed an Inspector of Agencies on the Dominion Lands Board. In 1884 Pearce was appointed Superintendent of Mines and was responsible investigating, reporting and making recommendations on disputed land claims.
Many disputed land claims extended from the Red River to the Rocky Mountains and from the 49th to the 56th parallels and were between settlers, large land interests and Metis communities. Pearce became Chief Inspector of Surveys in 1901. He voluntarily left his federal government post. From 1904 to 1911 Pearce worked for the Canadian Pacific Railway in the administration of irrigated lands and land in British Columbia.
He was responsible for reporting on potential land resources in regions of Manitoba, Saskatchewan, Alberta, and British Columbia. He was particularly occupied with the drainage of the Athabasca and Pearce Rivers. After 1912 Pearce was hired as a Statistician to the Department of Colonization and Development for the Canadian Pacific Railway, based in Calgary.
