Shelter Bay, Upper Arrow Lake, British Columbia

Shelter Bay along the Upper Arrow Lake in British Columbia. Those of you who have been following Project Canada for a while, know that the effects of dams, particularly in the Columbia River system, are becoming an important subject for the project. This lake is heavily affected by those dams.

Both the Upper and Lower Arrow Lakes, connected by a narrow passage, are part of the Columbia River system. Before dams were constructed, these lakes were nutrient-poor. A system being poor in nutrients could sound like a place where life has a hard time to survive, but in fact these systems often support a highly diverse group of creatures ant this was true too for these lakes. In those days before the flow of the river system was interupted and controlled by human-made dams, several species of salmon came to the narrow passage between the lakes to spawn, including the Chinook and Steelhead salmon. Salmon, wherever they swim upstream to spawn in great numbers, can be a keystone species for the natural system they arrive in. Countless animals like other fish, birds like bald eagles and ospreys and large mammals like bears, wolves and coyotes depend on what is a temporary boundless amount of food that the spawning and afterwards dying salmon provide. Such a food source is invaluable before winter sets in. Even after that, the eggs and the hatched fish in spring feed many more mouths. Amazingly, even plants profit directly from the salmon run. All the dying fish decompose and the resulting nutrients are absorbed by plants. In some areas, up to 75% of Nitrogen atoms in plants are directly derived from the fish that die there.

The building of the dams witout fish ladders, notably the Grand Coulee Dam in Washington (U.S.), made it impossible for salmon to reach their spawning grounds and thus removed a keystone species from a very large area. And what happens when you remove a keystone inevitably happened here too: the structure collapsed. As you can see, naturally the lake is still there and the mountains are still standing, but the natural system has changed dramatically. All species, be they plant, animal or even bacteria that dependeded on fish, suddenly were deprived of what had been an important foodsource for many thousands of years. Some could adapt and get valuable nutrients from another place or managed to do with less. Others however could not do either and perished. All in all, the building of the dams led very directly to a much impoverished natural system.

The First Nations living in the area also suffered heavily under the loss of the fish. They too had depended on the spawning salmon for many thousands of years. See more information here.

Image number: 2007_ASP4799LCA