Holes in the River

Mining Alberta’s floodplains.

By Kevin Van Tighem

Digging a mine in a river would be stupid, right? Well, in Alberta we do it regularly.

Ric Hauer tells the story of a new municipal water well drilled a kilometre away from Montana’s Flathead River. The Flathead, like most Alberta rivers, is what Hauer calls a gravel-bed river. Centuries of erosion and deposition have filled its valley floodplain with rounded cobbles and gravel. Water flows not just over those gravel beds but through them.

The river’s alluvial aquifer fills the whole valley floor. That’s why the new well produced sweet, filtered groundwater. And, surprisingly, stoneflies. Stoneflies spend most of their juvenile lives in fast-moving, well-oxygenated water—usually in river rapids. But the wriggly little nymphs in the town’s water well were nowhere near the river.

Hauer uses those insects to make a point. A leading authority on gravel bed rivers, the University of Montana scientist has studied these dynamic landscapes for four decades. He says simplistic views of river ecosystems can lead to big mistakes in how we live with them. “Most people look at the active channel and think ‘That’s the river,’ ” he says. “It’s not. At any given moment, there’s far more water in the gravels than in the channel.”

A river is, in fact, a three-dimensional landform. It includes the active, flowing surface channel, but it also extends laterally to include the whole floodplain and vertically into the groundwater and gravel deposits beneath. River water continually drains into the ground; groundwater continually emerges into the channel. It’s all connected.

Alberta’s old PC regime was all about keeping industry happy. Their 2011 policy threw the door wide open to more gravel mines.

That’s why the stoneflies turned up in the well. They were living in the dark, shimmering secret of what Hauer calls the “under-river”—the hyporheic zone of the river where surface and subsurface flows are one. The part that looks like land.

Alberta’s 2013 floods reminded us forcefully that, in major runoff years, the surface river occupies the whole floodplain, not just its summer channel. Every major flood teaches us this. Then we conveniently forget so we can profit from developing floodplain land. Less obvious, but no less important, is that even when the river seems safely back in its channel, it’s still flowing through the floodplain—just below the surface.

Hydrologists have a pet expression: The river owns its floodplain. More accurately, the river is its floodplain. And a gravel bed river is its gravel.

Gravel, however, is a valuable commodity—one of Alberta’s most widely mined materials. We use gravel for roads, cement manufacture and construction. The gravel (or “aggregate”) mining industry is big. Like other big industries, it lobbies government. Mining gravel from river floodplains is cheap and profitable. Industry covets the stuff because it’s both easily accessible and high quality.

Prior to 2011, government regulators rarely approved aggregate extraction on river floodplains. Experience both in Alberta and elsewhere has shown that robbing the floodplain often leads to aquifer depletion, fishery losses and “pit capture,” when river channels shift into the gravel mine pits.

The old PC regime, however, was all about keeping industry happy. It was inevitable that the gravel-mining industry would meet behind closed doors with government regulators. The outcome—with no public input or outside expertise—was the January 2011 Alberta Surface Water Body Aggregate Policy. Where in the past only a few floodplain gravel mines were approved, the new policy threw the door wide open.

Two years later, Mother Nature reminded us why that was a bad idea. The 2013 floods rearranged rivers across Alberta. Mixcor’s Dahm gravel pit on the North Saskatchewan River floodplain near Devon was swamped with water, burying equipment and leaving a gaping wound whose leaking silt devastated the downstream fishery. Downstream from Calgary, trout escaped turbulent flows in the main Bow River channel by moving into calm places on the floodplain—including gravel pits. Volunteers rescued over 5,000 fish trapped when the waters ebbed. Thousands more died.

Glaciers left lots of upland gravel in Alberta. There is no need to steal it from our rivers. The only reason mining river floodplains is profitable is because gravel operators don’t pay for the dead fish, depleted water wells, diverted river channels and downstream siltation. We do.

Alberta’s new government is reviewing the 2011 Aggregate Policy. Like the old government, however, they are listening most closely to those who profit from digging holes in our living rivers. Alberta Environment and Parks has made it clear that Alberta’s gravel bed river ecosystems will continue to be mined for profit. Maybe the next flood will finally get their attention. Expect more harm in the meantime.

Kevin Van Tighem’s latest book, Our Place: Changing the Nature of Alberta, was released in spring 2017 by RMB.


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