Nature Notes – From the Backyard to the Biosphere. Endangered Rivers: Our Wild Legacy in Jeopardy

Nature Notes – From the Backyard to the Biosphere. Endangered Rivers: Our Wild Legacy in Jeopardy

When most of us hear the word endangered, the free-flowing waters of North America’s rivers do not come to mind. Instead, we tend to think of a species of plant or animal in danger of extinction. But increasingly, conservation biology is centering on the health and integrity of whole ecosystems rather than focussing on only individual species. And this is where the concept of an endangered river comes into play.

American Rivers, a U.S.- based river-protection organization, defines an endangered river in much the same way that COSEWIC (the Committee on the Status of Endangered Wildlife in Canada) defines an endangered species. Endangered rivers are those “…facing a major threat to their health and (that have) a crucial turning point approaching in the coming year”. Both American Rivers and a Canadian organization – the Outdoor Recreation Council of British Columbia – publish an annual list of endangered rivers in their respective areas. These are worthwhile organizations to check out, as they are a rich resource for information on river health and stewardship opportunities.

North America’s rivers are suffering from a variety of ailments. Pollution from industrial, agricultural and domestic effluents and runoff are often exacerbated by the loss of vegetated “buffer” zones near river edges. In addition to direct loss of habitat for near-shore and wetland plants and animals, the loss of these buffers – known as riparian zones – limits the ability of the near-shore terrestrial environment to help absorb and filter pollutants en route to the river. Urban encroachment, and agricultural and industrial activities occurring too close to rivers, are the primary culprits in the loss of buffer zones.

When riparian vegetation is removed, erosion of the riverbanks is a frequent result, and siltation of the riverbed occurs. This is often worsened when mining and logging operations occur near a river, as soil and other debris previously held in place by vegetation begin to slide towards and enter the waterway. Siltation may not appear to be a great a problem for the health of a river; however, the quality of habitat that a river provides is strongly linked to the “shape” of the riverbed and banks. In some BC rivers, siltation has increased the height of the riverbed by four feet. This can dramatically alter flow and riverbed-material conditions in the river, eliminating spawning, feeding and hiding locations for a variety of river wildlife.

One can’t discuss river health without mentioning the effects of dams on these waterways. This is particularly so in Canada, a country with such a large dependence on Hydro-electric power. Two main issues surround the impact of dams on river health: firstly, dams directly impede the movement of river wildlife along the waterway. Even with the addition of fish ladders in some rivers, there is no question that the establishment of dams and the re-routing of countless waterways in North America and elsewhere have profoundly affected both fish and other river-related wildlife. Secondly, the presence and function of a dam lead to dramatic alterations in the volume and rate of flow of water in a given river. This means that what once may have been a stable habitat for a variety of fish and other wildlife is now a distinctly unstable location with water levels rising or falling many metres in a short time period.

The state of North America’s rivers is certainly enough to bring one’s mood down a notch or two. However, there is a great deal of activity directed towards improving the health and fate of these waterways. Much of this activity is locally based. As American Rivers states, “once ignored and abused, rivers today are being rediscovered and embraced by the towns along their banks”. River stewardship groups, such as Toronto’s Don River Regeneration Council, are working to restore the health of local waterways.

One exciting result of this group’s endeavours is the transformation of a former landfill into two productive pond and wetland sites. The organization states that the “…simplest and least expensive way to begin regeneration is with recreating habitat on the land. By planting native trees and shrubs we create a place and food sources for breeding and migratory birds and mammals”. This is in keeping with the suggestions of the American Environmental Protection Agency’s guidelines for river restoration practices.

Another promising method of improving river health is the removal of dams. This may sound surprising, as the dismantling of these mammoth engineering projects is no doubt a costly endeavour. However, in the US, close to 500 dams have been removed from river-ways. While undoubtedly a large undertaking, dam removal is proving to be one of the most direct and effective ways of improving both the health of rivers, and the social and safety considerations related to these waterways.

In both Canada and the US, the potential of local efforts in river restoration, pollution abatement, dam-removal and dam avoidance cannot be underestimated. Each bit of riparian zone restored or left to regenerate, each small dam removed, each pollutant kept from entering a river is one huge step in setting the precedent for stating that our rivers are important to us. Their wildness, their freedom: these qualities are a part of our national and natural heritage, and our involvement in protecting rivers is crucial if we are to keep the term “Extinct rivers” from being added to our common vocabulary.

To learn more about river health and protection, take a look at the following web sites:

Zoe Dalton is a graduate of York University’s environmental science program, and is currently enjoying working towards a Master of Arts in Integrated Studies with Athabasca U. She can be reached for comments or questions at

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