How do you measure the health of river? An angler, canoeist or cottager would certainly have some good ideas, perhaps based on the number of fish they’ve caught, or the quality of water that they’ve swum in or even drunk. When you ask someone like me – a scientist, numbers nerd, and avid camper – I see the technical challenges behind this question. To me, the challenge is how to compile a set of these types of indicators and create a rigorous framework for evaluating the health of aquatic ecosystems across the country. That’s the challenge that WWF-Canada’s Freshwater and Conservation Science teams have tackled in developing our Freshwater Health Assessments.
Role Models, Near and Far
To get started, we hit the books and consulted what has been done elsewhere around the world. We looked to existing programs for evaluating water health in countries like Australia and South Africa, which have been monitoring, analyzing and reporting on river health since the 1990s. Similarly, the United States has been monitoring river health for more than a decade. More recently, the European Union set a goal of all waters in good condition by 2015, which has spurred development of a wide range of methods to assess river health. Here in Canada, there have are also some excellent examples of reporting on aquatic ecosystem health, typically completed at a watershed scale, including in the South Saskatchewan River and the St. John River, as well as through Ontario’s Conservation Authorities.
Recruiting the Experts
After surveying the best international practices, we consulted Canada’s scientific experts. Starting back in the spring of 2011, we sat down with a group of freshwater scientists and representatives from government, ENGOs and academics, and asked the tough questions on how these types of assessments and reporting could be completed in a credible and consistent way across the country. The answer was that it could be possible, but that it was going to require a lot of work and it wasn’t going to be easy!
Choosing our Metrics
By collaborating with scientific experts, we created a framework for evaluating river health that consists of a group of four key metrics: hydrology (or water quantity), water quality, fish, and benthic macroinvertebrates (cool things like snails, worms and insects that live on the bottom of a river). These metrics reflect a broad range of components of aquatic ecosystems, so together, they could provide a snapshot of that ecosystem’s health. Many of these metrics are also typically included in the leading programs we’ve seen around the world, so they’re significance is widely recognized. And perhaps most importantly, there are monitoring programs in place in many of Canada’s provinces and territories to provide the data that are required as the basis for any assessment of these metrics, so we’d have something to work with from the outset.
Data, Data, Everywhere
Data. That’s where the rubber hits the road for any scientific analysis, and also where we faced some of our greatest issues in completing the freshwater health assessments. WWF’s Freshwater team reached out to government agencies across the country to request data for inclusion in our analysis. Our assessments are based on data that are both available and accessible from public sources. In some cases, the data used in our assessments were from online databases, like those from federal monitoring initiatives, including the Water Survey of Canada’s online database of hydrometric data, and Environment Canada’s monitoring program for benthic macro-invertebrates. We also gathered data from provincial monitoring programs like Alberta’s monitoring of surface water quality, or Ontario’s databases for benthics and water quality. Where online databases didn’t exist, we contacted the relevant government agencies directly.
Drawing the Line: How Much Data is Enough?
How much data are enough to confidently report a score? We wanted to avoid extrapolating results from a limited set of monitoring points to a watershed score in creating the Freshwater Health Assessment methodology, because it can really distort the results. To minimize this risk, we created a set of criteria to evaluate the sufficiency of the data, based on the geographic distribution and length of monitoring. For example, we couldn’t defensibly report a score for an entire watershed based on one year of sampling from a single site on a river. Ideally, our analyses would be based on long-term monitoring from a network of monitoring sites that are distributed throughout a river’s watershed.
Since Canada’s watersheds can be very large areas, we decided to adopt smaller sub-watersheds as the unit for our analysis (specifically the Water Survey of Canada’s sub-drainage areas). That way we can see differences in aquatic health within a watershed, which may be important for regional or local organizations. For example, the Fraser River assessment was completed for its four sub-watersheds (the Nechako, Upper-Fraser, Thompson, and Lower-Fraser), then rolled up to an overall watershed score.
We also established thresholds on the number of metrics and proportion of sub-watersheds that had sufficient monitoring that were required to confidently report a watershed score. As a consequence, some sub-watersheds and even watersheds received overall scores of “Data Deficient”, which indicates that the available (and accessible) monitoring data too limited for us to reliably report a score.
The Start of Something Big
After countless hours of crunching numbers, running statistics, and mapping monitoring data, we’ve completed a novel assessment of freshwater health for seven river systems: the Skeena, Fraser, Athabasca, South Saskatchewan, Thames, Ottawa and St. John. We plan to use the methodology we’ve developed as a foundation for a national assessment of all Canada’s major water bodies by 2017. Through continued collaboration with scientific experts, we hope to build on this assessment framework, to improve it over time as new science developments are made and as new data emerge, and even expanding the assessments beyond rivers to include lakes and wetlands.
So next time you’re out paddling in a canoe or reeling in a fish and wondering to yourself about the health of your watershed, know that WWF-Canada is working to answer this question!
To learn more about the methodology used in WWF-Canada’s Freshwater Health Assessments, including a full list of data sources used, please consult our methodology report.