This month, WWF released the first half of a Canada-wide assessment of our 25 most prominent watersheds. The assessment focused on four indicators of watershed health and seven key threats. Measures of health included hydrology, water quality, fish, and benthic macro-invertebrate communities. The seven key threats assessed were pollution, climate change, alteration of water flows, invasive species, water use, fragmentation, and habitat loss.
How did our watershed do?
The North Saskatchewan River watershed ranged in overall threat level from moderate to very high. You can see the data for our watershed here.
Edmonton and area received a rating of “high.” The biggest threats to our watershed were pollution and fragmentation, which were assessed at “very high”; this was closely followed by habitat loss. Climate change posed a moderate risk, while overuse of water and invasive species were listed as low risk.
The main source of pollution to our watershed is agricultural runoff. Fragmentation was largely driven by roads and rail infrastructure as well as dams.
What’s threatened in our watershed?
More than 1.2 million people live within our watershed, the majority of which are located in the greater Edmonton area. We share this important habitat with moose, elk, woodland caribou, and the endangered burrowing owl. Our river contains 27 native fish species, including massive Lake Sturgeon, a species dating back to prehistoric times that is increasingly being threatened by urban development and expansion.
How was health assessed?
This section is meant to summarize the health indicators used in the WWF assessment. You can find WWF’s detailed methodology here.
Hydrology accounts for changes in a river’s flow, or the amount of alteration from its natural flow regime. WWF’s assessment measured trends in monthly and annual flows over time.
If large dams (ie. greater than 10m in height) were present, hydrology was assessed between pre- and post-dam conditions. If no large dams were present, the test was completed comparing monthly flow with a benchmark or related historical time period.
Water quality is often monitored for its consequences to aquatic life and relevance for humans, primarily for drinking water and recreation. The assessment focused on chemical components rather than biological (eg. E. coli or other bacteria, viruses and protozoa). This section focused on aquatic life, though future iterations may focus on other indicators more related to or specifically related to human health and wellbeing.
Fish are an important part of aquatic health. Not only are they integral in aquatic food webs, but also are of high commercial and recreational value to humans.
Fish – and all life – can be assessed at different levels. For example, species richness can be assessed coarsely, where it provides a snapshot of overall health; species abundance can be studied to show population-level health; and size and weight can be measured for individual analysis. Most publicly availably data is based on species presence or absence or focused on individual species of commercial or recreational value.
WWF used the Hilsenhoff Biotic Index (HBI) to determine the health of benthic macro invertebrate communities. The HBI accounts for sensitivity of benthic invertebrates to disturbance and indicates degree of disturbance of the sampling location (based on their relative abundance in the sample).
WWF aims to have the assessment complete by our country’s 150th birthday in 2017. To learn more about the assessment and see how your watershed is doing, visit the site here.