By Claire Eamer
Major water-users in the Yukon are issued licences that tell them how much water they are allowed to use. And who has the biggest allowed use? Placer mining, at 93 per cent of all permitted water usage.
“Most people will find that surprising,” says Holly Goulding, a water adaptation analyst with the Environment Yukon.
“The water-use picture here is quite different from the rest of the country.”
Goulding has spent two years analyzing Yukon water resources and their vulnerability to climate change. Placer mining is just one of the Yukon sectors that depend on a good, steady supply of fresh water. Hydro power, for example, is at least as dependent on large amounts of readily available water, although - unlike placer operations - hydro facilities return the water to the watershed largely unaltered.
Climate change is already having an impact on the Yukon’s water resources, and the effects will increase as the world gets warmer, Goulding says. People in the Yukon take plenty of water for granted, but it’s not an unlimited resource. And it’s vulnerable. Most of our water comes from the deep freeze. In southwestern Yukon, the streams and rivers are fed by glaciers built up by millennia of snowfall. In the east and north of the territory, the rivers are fed mostly by annual snowmelt. Changes in the amount and timing of snowfall and glacier melt will mean changes throughout each watershed.
Sometimes climate-related changes are dramatic.
In December 2002, for example, temperatures in the Dawson area turned so warm that the Klondike River broke up. Ice pans floated down the river and grounded in a shallow spot. Broken ice piled up until there was a three-kilometre ice jam that raised the river level about two metres.
The river level dropped again, along with the temperatures, but the jam froze in place. In April, rain and warm weather sent water and ice piling into the old ice jam. In 24 hours, the water level rose three metres, the river poured over its banks, and the Dawson area had its worst, most expensive flood in years - possibly its first-ever climate-change flood.
In 2007, in Old Crow Flats, the water went down instead of up. Two lakes drained in just a few weeks, apparently as a result of warming and decaying permafrost along their shores. Zelma Lake, at about 12 square kilometres, was among the largest lakes in the Flats. In early June, it was almost full, with a small stream draining slowly into the Old Crow River. By late July, there was nothing left but a small pond.
Most changes to the Yukon’s water resources won’t be that dramatic, but we need to be ready for them nevertheless, Goulding says. Climate change could affect everything from how much water is available and when, to the quality of the water.
Predicting the changes and preparing for them isn’t simple since they will vary by watershed. In the upper reaches of the Yukon River watershed, where glacier meltwaters drain into the Southern Lakes and feed the river, warmer springs and summers will lead to increased melting. At first, that could mean more water, but the flow will diminish as the glaciers shrink and retreat.
In watersheds fed by snowmelt, the amount of water in streams depends mainly on the amount of snow. Peak flows occur when the snow melts, and that has been happening earlier and earlier in the Yukon in the past few decades, says Goulding.
A complicating factor in both kinds of watersheds is permafrost, particularly in the central and northern Yukon. Both air and ground have been warming, and as the ground warms, the active layer of thawed ground above the permafrost gets deeper. Meltwater sinks further into the ground and percolates through dirt and gravel on its way to the nearest stream, picking up sediment and dissolved minerals as it goes and changing the quality of water in the stream.
All of these changes will have impacts on economic sectors, like mining, hydroelectric generation, agriculture and on water supplies for Yukon communities. But there are other, equally important water uses that don’t show up on the balance sheet, Goulding says. A catch-all term is ecosystem services.
Ecosystem services are all those things that water does for us, simply by being there.
Provisioning services cover water’s role in providing us with food, water for domestic use, and basic materials such as wood and fibres. Regulating services are the controls water and aquatic ecosystems exercise on climate, flooding, disease, waste disposal and water quality. Cultural services include recreation and aesthetic and spiritual benefits. Think of the restorative power of a quiet summer’s evening by a lake! And supporting services are natural processes, such as soil formation, nutrient cycling, and photosynthesis.
Water, in the natural ecosystem, provides all of these services, Goulding says. That means it’s important to take them into account when planning for and managing our own direct use of water. Essentially, she says, we need to allocate water for nature before we allocate water for human use, if we want to maintain a healthy, intact aquatic system that can keep on doing its natural job.
For more information about Yukon water resources and their vulnerability to climate change, catch Holly Goulding’s Yukon Science Institute lecture in Whitehorse on Sunday, March 20, at 7:30 at the Beringia Interpretive Centre, or in Haines Junction on Monday, March 21, at 7:30 in the Kluane National Park Visitor Centre.
Goulding will be joined by Sarah Laxton of the Yukon Geological Survey, talking about permafrost and climate change.
This column is co-ordinated by the Northern Research Institute at Yukon College with major financial support from Environment Yukon and Yukon College. The articles are archived at www.taiga.net/yourYukon.