RIVER ENVIRONMENT

The moderate current which has been described as characteristic of the Upper Pelly for some distance above the confluence, continues to its mouth, but the Lewes is much swifter, and though at the point of junction divided among wooded islands, is evidently the larger stream, carrying a volume of water considerably greater than that of the Pelly, though probably less than twice as great.
—George Dawson, 1887

Early explorers thought that the Yukon River flowed into the Pelly rather than the other way around. This is an easy mistake to make for at this junction the rivers seem to be of a similar size and the flow appears to be westward, following the course of the Pelly. As can be seen in Dawson’s quotation above, the Yukon River above Fort Selkirk was originally called the Lewes. Geologist George Dawson determined that it was actually the upper portion of the Yukon River.

The glaciers that passed over this area laid down layers of gravels and boulders. The large boulders, and the hollows made by water cutting around them, cause the boiling effect seen in the Yukon River. The current here is quite swift, approximately 7 kph (4.75 mph). That, combined with the loose glacial gravel and rock, makes for a constantly shifting river bed. As the river water levels fluctuate with the seasons, the turbulent waters cut away and redeposit material changing the shape and location of bars, islands and channels. This is particularly evident at the confluence of the two rivers where there are several large gravel bars covered with debris washed down from both rivers. The movement of ice also plays a major role in shaping the course of the river as it gouges out banks and bars. At narrow places, like Victoria Rock (Tthi Ts’et’yan or Tthi Ts’ach’an), the ice often jams up forming dams that back water up the river valley and cause flooding.

The constantly shifting channels and bars proved a major hazard to sternwheelers. The ships often had to cut new channels in the spring by aiming their paddlewheels downstream and backing their way through the sands and gravels.

Before the sternwheelers, the river was a natural route for First Nations people traveling north on the Yukon or east on the Pelly. While they sometimes poled back upstream sticking to eddies and the slower water near the bank, it was often easier just to walk. In winter, people traveled on the ice. The ice around Fort Selkirk is notoriously treacherous, the turbulent and swift water often keeping patches open or very thin.

The river and its valley is also "nature’s highway" not only for fish but for migrating birds as well. The gravel bars near Fort Selkirk are an important resting area for migrating birds, particularly the sandhill cranes that stop here in the spring and autumn. The loose gravels of the Yukon River valley allow seepings of ground water into the river and sloughs. This makes excellent habitat for spawning Chum salmon. The waters near the Ingersoll Islands are favourite spawning grounds for larger chinook salmon. The isolation of the islands also makes them a preferred calving ground for moose in the spring, a place of sanctuary where they have some degree of safety from predators. In the spring, the south facing hillsides of the river valley are a favoured habitat for grizzly and black bears, as well as sheep later in the summer. The hillsides warm early and green up quickly. Tender shoots and roots are an important part of the ursine diet.

As the river changes course, sloughs are formed where the water moves slower. Due to the upwelling ground water, the sloughs are warmer in winter and cooler in summer. This is a good place to see ducks such as the Barrow’s Goldeneye nesting and feeding. The sloughs also support shore birds such as spotted sandpipers and the lesser yellow legs.

The boulder and cobble bottom of the river supports a wide variety of aquatic insects, including may flies, stone flies, caddis flies and the dreaded black fly that spend their nymphal stage clinging to rocks in the fast current. The insects are particularly vulnerable when hatching or ovipositing (depositing their eggs). At this time they provide protein rich food for the fish and bird species of the riparian zone.

Victoria Rock marks the point where the river enters the Yukon River gorge. While this is not a dramatic rush of white water, the character of the river valley changes markedly from the open flats dotted with islands seen above Fort Selkirk, to the deeper, lusher valley seen downstream to the mouth of the White River.

The richness of life in the river valley also attracted people. First Nation people fished and traveled seasonally along the rivers. Once contact was made with outside traders, the river became even more important as a transportation route. Trading posts and settlements were built along the rivers which offered transportation, plenty of fish and game and, often, richer soils for growing crops.

While the third Fort Selkirk was built on a stable bench that has not seen flooding in many generations, the river has claimed back other settlements. A large pre-contact fish camp near Victoria Rock has all but washed away. The original Fort Selkirk was abandoned due to regular flooding. Often cabins built well back from the river bank are washed away within a few decades because of progressive bank erosion.

Figures of Interest:

• Typical open water season: May 10 - October 25
• Typical ice cover season: October 25 - May 10
• Peak water flow around June 5
• Maximum recorded water flow: 7,700 cubic metres per second (June 25, 1962)
• Minimum recorded water flow: 227 cubic metres per second (March 29, 1959)

Further Reading:

Dawson, George. Report on an Exploration in the Yukon District, Northwest Territories and Adjacent Northern Portion of British Columbia. Whitehorse: Yukon Historical & Museum Association, 1987 (reprint of 1888 edition)

Yukon 1992 Historical Streamflow Summary. Water Survey of Canada, Department of the Environment, 1992.