"Duncan Lake (not Upper Kootenai Lake)" adopted 30 June 1902 in the 4th Report of the Geographic Board of Canada. "Howser Lake or Duncan Lake..." listed in the 1909 BC Gazetteer. Duncan Lake confirmed 3 July 1947 on Columbia River Basin manuscript 12, as a well-established name. Due to flooding behind Duncan Dam (mid-1967) the lake now extends from 50 15 - 116 56 to 50 37 - 117 02. Application altered 18 January 1971 to include increased length.

Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office

Labelled "Upper Kootenay Lake" on Walter Moberly's plan of the Upper Columbia District, c1866, and on Trutch's 1871 map of British Columbia. Labelled "Upper Kootenai Lake" on GSC map of West Kootenai District, 1890. Labelled "Howser Lake" on John Retallack's 1893 Map of the Town of Lardo [sic]. Labelled "Duncan Lake" on Perry's mining map of the West Kootenay, 1893, and on Jorgensen's map of British Columbia, 1895. Labelled "Duncan or Howser Lake" on BC Lands map of West Division of Kootenay District, 1897. Labelled "Howser Lake" on BC Lands map, East & West Kootenay, published in 1898, 1902 & 1911. Reverted back to Duncan Lake on maps published from 1912 onwards.

Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office

"It appears that the lake was originally called Ecclesion by Father DeSmet, as shown on his 1846 map (Victoria Archives) and was then called Upper Kootenay by Turnbull, Moberly and Green on their 1865 map. Other maps up to this date do not appear to differentiate the lake from the larger Flatbow (now Kootenay) Lake. In 1892 the lake was identified as "Howser or Upper Kootenay Lake" on survey plan of Lot 528 [being pre-emption record 147, William Simpson & Shirley Keeling, 25 August 1892]. In 1893 it was called "Howser" on John Retallack's Map of the Town of Lardo, Kootenay Lake [National Archives of Canada call number H2/640/Lardo/1893, record 28495, microfiche NMC 24227]...." (research and advice provided August 2005 by Paul Howser, Reigate, Surrey, UK, with photocopy portions of Simpson's pre-emption and Retallack's map, file H.1.54.) "...the name "Duncan Lake" appears to have been first used by Perry on his [Mining map of the West Kootenay] of 1893. The 1896 Map of the West Division of Kootenay District BC by G B Martin shows the lake as "Duncan or Howser" - it should be noted that from 1898 to 1911 the lake is named on 19 maps as Howser and on 4 maps as Duncan." (additional research provided June 2009 by Paul Howser.)

Source: included with note

The lake takes its name from Duncan River, in turn named after John ("Jack") Duncan, prospector & candidate for the legislative council from Kootenay District, 1866; died c1900.

Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office