The Great Lakes hold an estimated 23 quadrillion litres of water and cover about 244,000 square kilometres while draining more than three times as much land. Most of this water enters the system naturally via groundwater pathways, surface run-off and precipitation, but there’s also a human element to this story. A small portion of this huge water input comes from people manipulating its flow: two major water diversions at the northwesternmost point of the watershed redirect rivers that once flowed north toward James Bay, changing lives and livelihoods for First Nations in the region.

When the Second World War broke out, it spurred governments on both sides of the border to generate more electricity, a concept they had been considering for decades. “Every cubic foot of water diverted from the relatively useless basin of Hudson Bay into the lakes will prove liquid gold,” wrote one commentator in a 1925 op-ed in the Chicago Tribune. By adding water volume at the top of the system, the two governments found they could increase the flow rate of water over Niagara Falls to reap the power benefits, while also enhancing the scenic beauty of the falls.

To do this, a set of two control dams were completed in 1943 to redirect a portion of the Ogoki River into Lake Nipigon and ultimately into Lake Superior. Other dams opened in 1941 reversed the Kenogami River through Long Lake and also toward Lake Superior. The two diversions are the only human-made water diversions into the Great Lakes.

But this feat of engineering didn’t just increase the volume of water flowing over Niagara Falls: the Long Lake and Ogoki River diversions altered water levels and fish habitat, both along the Albany River system to the north and in the Long Lake and Lake Nipigon watersheds.

The Whitesand First Nation once lived on the northwest shore of Lake Nipigon, but as water levels rose in 1942 following the diversions, eroding the shoreline and flooding homes and burial sites, the community relocated closer to Armstrong, Ont.

“That loss of land, and all those trees, that our people had hunted and fished … it was a very emotional trip for me,” said Whitesand First Nation Chief Lawrence Wanakamik following a recent fly-over of the Ogoki Reservoir, Summit Control Dam and Waboose Diversion Dam. “It has affected a lot of people, not only our members but people north of us. There are stories of graves that were washed ashore or washed into the water.”

The dams have also contributed to increased levels of methylmercury in fish. When soil is flooded due to dam construction, organic carbon is released, fuelling microbes to convert naturally occurring elemental mercury to toxic methylmercury, which then rises up the food chain.

“We can only eat two fish a month from the Little Jackfish River beneath the reservoir,” says Chief Wanakamik. “So a lot of people don’t fish at all for eating.” A poignant image to keep in mind while admiring Niagara Falls.