What Makes a River Healthy?
The Elk River watershed interlaces the valley, providing clean water for vegetation, wildlife, and humans. Healthy streams are vital for all life; but what makes a stream “healthy?” The Elk River Alliance has monitored Elk Valley waters for over a decade, and we’d like to explain.
Bugs ain’t all bad!
The healthiest streams, as one might imagine, are those that can sustain a thriving, biodiverse ecosystem. Benthic invertebrates (science-talk for “aquatic spineless creepy-crawlies”) are an excellent start to understanding stream health. Because they are small and have a short lifespan, the types of invertebrates living in a stream can quickly change if water quality suddenly degrades.
The Elk River Alliance collects invertebrate samples, has them analysed by a taxonomist, and assesses the invertebrate community. Some insects (stoneflies, mayflies, and caddisflies) are indicators
of good water quality; they are sensitive species that need lots of oxygen and clean water to thrive. Conversely, other organisms (such as Tubifex worms, leeches, and mosquito larvae) are more resilient to low oxygen and pollution. Seeing a sudden shift from good indicator species to bad indicator species can suggest stream health is degrading and we need to take a deeper look at the cause.
What allows water to bear life?
Keeping in mind that the defining quality of healthy water is its ability to sustain life, the importance of some water quality parameters is obvious. Dissolved oxygen, for example, is clearly essential for aquatic organisms. Dissolved oxygen increases as air and water mix in waterfalls, rapids, and riffles, and decreases as water slows or becomes warmer. Temperature not only impacts oxygen levels, but many organisms have thermal limits which, when exceeded, cause stress and eventual death.
Other parameters, like sediment levels, are less obvious. Sediment in the water is natural and increases every spring as the snow melts. However, excessive sediment over prolonged periods can become harmful by clogging the gills of fish and insects. Sediment can also choke gravel beds which are vital for fish spawning and invertebrate habitat. Heavy metals, such as selenium and mercury, can accumulate in animal tissues, including ovaries, causing body deformations in their offspring. Other chemicals, like nitrates and phosphates, feed algal growth which can then reduce oxygen level as bacteria decompose the dying algae. In the Elk Valley, heavy metal and nutrient pollution are common by-products of industrial coal mining but can also come from other sources.
These are just some of the many factors that define the “health” of a stream, so it’s important to keep a close watch on them. Throughout the valley, the Elk River Alliance maintains 19 temperature loggers, three active hydrometric stations, and ten sites where we monitor benthic invertebrates, water chemistry, and physical parameters. Many organizations, including governments, municipalities, consultancies, resource companies, and other not-for-profits also collect water quality data.
An informed community makes informed decisions.
Understanding water quality is the first step to maintaining healthy streams. The next step is ensuring the information is available to the public. Using the data collected, the Elk River Alliance provides pertinent information for Elk Valley citizens in an easily digestible format though online fact sheets, outreach booths, signage, and at public events. Having a well-informed population is vitally important so decisions can be evidence-based when water quality concerns arise.
More than providing information, ERA is working to restore impacted areas to create a beautiful and productive ecosystem. We rally the community to collect trash during our annual clean-up, plant plants to restore a former gravel pit into a wetland, and pull invasive species. This fall we’re looking for volunteers to help us plant cottonwood trees in streamside areas around the valley. This effort will not only provide a habitat for fish and other animals, but naturally stabilize riverbanks to prevent erosion.
If you would like to join the Elk River Alliance volunteer team, please visit elkriveralliance.ca/volunteer.
Photo: ERA volunteer Chris Bush sampling for benthic invertebrates in Lizard Creek.