How does your river look today?

By Submitted Article on September 18, 2020.

SUBMITTED BY THE SOUTHERN ALBERTA GROUP FOR THE ENVIRONMENT

The next time you cross the Whoop-up Drive bridge, glance over the edge and consider your Oldman River. What do you see? Ask yourself, “Is there too little or too much water?” and “Should I be concerned?”

Take a moment to consider how the flow you see compares with flows during this and other years. Seasonal and annual variability is the key to understanding river function.

Water is essential for all life – ours and our ecosystems. Our prairie region is naturally treeless. Grasses and hardy shrubs are adapted to the semi-arid climate where regular droughts prevent trees from thriving. The exceptions are the natural woodlands rooted in the moist places next to rivers, streams and wetlands. These plants stabilize soils and support other species that can’t otherwise survive here. The waters themselves are home to diverse aquatic life dependant on the seasonal ebb and flow of precious moisture.

Seasonal flow ranges are a critical part of the system. During the winter, snow accumulates at higher elevations. As spring arrives, meltwater and rains send a pulse of water downstream. This flow gradually lessens to a trickle as summer heats up. Repeated every year for millennia, this seasonal pattern has shaped life on the prairie and beyond. Daily snows, rains and temperatures make every year slightly different within a natural range of variability. Occasionally, wet or dry periods set new records in the flow history. These events are often ecologically important as they physically shape riverbanks and encourage or limit dependent species.

The availability of water has likewise shaped human settlements and ingenuity. Our ever-increasing demand for reliable, clean water to supply cities, agriculture and industry has driven the race to capture, divert and store flow whenever and wherever possible. There are three major dams and numerous other diversions upstream from us. A complex basin model is constantly updated using flow gauges to maximize efficiencies. The licensing system accounts for every drop of water flowing through the system.

While moderated stream flows are convenient for us, river ecology can be profoundly affected by our tinkering. The “natural flow regime” is fancy talk for the pattern of quality, quantity, timing and frequency of non-regulated stream flows. These characteristics are the foundation of river ecology. Altering the flow regime will cause ripple effects through all dependent landscapes and organisms. Everything from channel movements and soil beds for plant seedlings, to spawning sites for fish and habitat for migratory birds, are all tied to these patterns of flow.

We think of this water as “ours,” but it’s just starting its journey and we are responsible to those downstream. We are at the top of a much larger watershed that eventually drains east into the Hudson’s Bay. In fact, we’re part of the “Crown of the Continent” where, if you look west from Fernie, the water heads off to the Pacific Ocean; north of Banff it ends up in the Arctic Ocean; and south of Milk River it flows to the Gulf of Mexico. Population growth, development expansion and climate warming are all growing threats to our limited water resources. We need to recognize the value in protecting our natural flows and variability to keep the whole watershed healthy.

So, “should you be concerned?” The answer is “you bet!”

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