Duhamel Creek – a favourite local watershed. Photo by Kim Green

The term ‘sustainable watershed management’ seems to mean different things to different people with different points of view. As a watershed geoscientist who has studied watersheds of the Columbia and Rocky Mountains for the past 20 years I have gained some insight regarding how watersheds work and for me, the term ‘sustainable watershed management’ implies the preservation of the key underlying physical processes in a watershed that govern water and sediment transport. It is these physical processes that underpin ecosystem integrity in a watershed. These are the processes that shape the streams, feed the riparian areas and provide aquatic habitat for both terrestrial and aquatic species. Of these physical processes a watershed’s flow regime, which refers to the wide range flood flows and low flows that occur over time, is the most critical attribute to manage.

One thing that has become very clear in my study of roughly 150 watersheds in the Columbia Basin is that, like people, watersheds are unique and resource development activities that are sustainable in one watershed are not necessarily sustainable in another. This is because the physical factors controlling the flow regime which, in turn, controls channel condition and sediment and nutrient transport through a watershed differ from watershed to watershed. These factors include the underlying geology, the character of glacial sediments, the aspect (the direction the slopes face), elevation and steepness of the watershed. In addition, the land cover including the forests, shrubs, grasslands and alpine areas and how land cover has changed over time also plays a role in determining the underlying physical processes and the potential for watershed response.

In BC we are in the initial stages of grappling with the term ‘sustainable watershed management’ on a Province-wide scale as we face our newly enacted Water Sustainability Act. As our Provincial legislative and policy experts at West Coast Environmental Law and UVic’s POLIS group have pointed out, this new Act has the potential to provide robust, long-term protection to our groundwater resources, fisheries streams and consumptive-use surface water supplies but it also has the potential to create years of confusion and uncertainty if the Province does not provide adequate resources to support it. Specifically, while the Act includes powers to make orders to protect “critical environmental flows” in times of scarcity (s. 86-87), our ability to define ‘critical environmental flows’ in a stream is limited by whether there is sufficient, good quality, long-term flow data for a watershed as well as whether there exists the basic knowledge of how flows and aquatic values are linked. In order for this new Act to have any success the Province must put their money where their mouth is (so to speak) and fund an effective research program geared at understanding the science behind the legislation.

I have no doubt that our path towards sustainable watershed management will be full of twists and turns. It could also be financially painful to the Province as Annual Allowable Cut (AAC) levels decrease in response to an improved understanding of ‘sustainable’ levels of resource development in watersheds. The good news is that we are already starting to make some progress down this path. In 2016, BC’s Chief Forester decreased the AAC in Kamloops Timber Supply area watersheds in response to recognition of the negative effects on aquatic values of elevated harvest levels associated with mountain pine beetle salvage activities.


Guest blogger, Kim Green

Although it is early times in our collective journey towards an improved understanding of what ‘sustainable watershed management’ means I am hopeful. In my 20 years as a watershed geoscientist I have observed that there are so many people in this area including government, industry, recreationalists and water users that share a fundamental desire to learn about and protect Columbia Basin watersheds. As my parting comment I would like to share two quotes, one by Also Leopold (1887 – 1948), and one by his son, Luna Leopold (1915 – 2006).

“Learn to read the land (river), and when you do, I have no fear of what you will do to it, or with it. And I know many pleasant things it will do to you.” (Aldo Leopold, 1947, “Wherefore Wildlife Ecology?).

Aldo Leopold’s son Luna, was a visionary American geologist who spent many years dedicated to the study of watershed processes.

“There is a need to place such common resources as water, land, and air on a higher plane of value and to assign them a kind of respect that Aldo Leopold called the land ethic – a recognition of the interdependence of all creatures and resources.” (Luna Leopold, 1997, Water, Rivers and Creeks).

Article submitted by:
Kim Green P.Geo., PhD
Apex Geoscience Consultants Ltd.

Notes on quotations:

These two quotations appear together at the head of
Ellen S. Verry, C. Andrew Dolloff. 1999. “The challenge of managing for healthy riparian areas.” in ed. Ellen S. Verry, James W. Hornbeck, C. Andrew Dolloff. 1999.

Riparian Management in Forests of the Continental Eastern United States. CRC Press.