Wednesday, 12. The weather was the same as yesterday, and we proceeded between three and four in the morning. We took up the net which we had set the preceding evening, when it contained a trout, one white fish, one carp, and three jub. The lake is about two miles in length, East by South, and from three to five hundred yards wide. This I consider as the highest and Southern-most source of the Unjigah, or Peace River, latitude, 54. 24. North, longitude 121. West of Greenwich, which, after a winding course through a vast extent of country, receiving many large rivers in its progress, and passing through the Slave Lake, empties itself into the Frozen Ocean, in 70. North latitude, and about 135 West longitude.

So wrote Alexander Mackenzie [1764–1820] in June 1793 , crossing the continental divide on his way to the Pacific Ocean. His latitude was precise; longitude is more difficult, especially if you’ve lost your watch.

The lake was named in 1910 by British Columbia land surveyor T. H. Taylor, who was employed that year by the BC Government to explore and survey the Parsnip River and the McGregor River. “This lake is at the Pacific-Arctic Divide; the water is clear as crystal.” (Extract from Reports of British Columbia Land Surveyors, Cariboo District, 1891-1927.)