Friday, 16 August, 1793. The weather continued to be the same as yesterday, and at two in the afternoon we came to the carrying-place which leads to the first small lake; but it was so filled with drift wood, that a considerable portion of time was employed in making our way through it. We now reached the high land which separates the source of the Tacoutche Tesse, or Columbia River, and Unjigah, or Peace River: the latter of which, after receiving many tributary streams, passes through the great Slave Lake, and disembogues itself in the Frozen Ocean, in latitude 69-1/2 North, longitude 135. West from Greenwich; while the former, confined by the immense mountains that run nearly parallel with the Pacific Ocean, and keep it in a Southern course, empties itself in 46. 20. North latitude and longitude 124. West from Greenwich.

Mackenzie believed it to be the Columbia, or a major tributary thereof, and Lewis, and Clark, in 1805 the next non-Indigenous party to cross the northern part of the continent of North America, shared the assumption. Mackenzie’s coordinates are accurate for the mount of the Mackenzie River, to which the Unjigah or Peace is a tributary. His coordinates for the mouth of the Columbia River are also accurate, but he was mistaken in thinking that Tacoutche Tess was the Columbia; it is the Fraser River, neither the Columbia nor a tributary, but this was not discovered until 1807 by Simon Fraser.

We embarked on this lake [Pacific Lake], which is in the same course, and about the same size as that which we had just left [Portage Lake], and from whence we passed into a small river [James Creek or Bad River], that was so full of fallen wood, as to employ some time, and require some exertion, to force a passage. At the entrance, it afforded no more water than was just sufficient to bear the canoe.

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.)