Canada is in an interesting position to increase exported electricity to the US via the sustainable form of hydropower.

Canada currently has 90,000 MW of nameplate capcity distributed over 475 hydroelectric power plants . The largest of this facilities is even larger than Grand Coulee Dam at 7276 MW.

Hydroelectric Dam Atlas of Canada (big file)

In the US hydropower counted for 6% of total electricity power in the US. US installed capacity is at 80,000 MW. Currently China is building the tallest dam in the world (312 meters) - Shuangjiangkou Dam to damn a narrow river and produce 2000 MW. The project is quite controversial but Approval has recently occurred

There are currently about 80,000 dams in the US but only 2500 of them are hydroelectric. There is a serious move to therefore put turbines on many existing dams . This is much more efficient than building new dams.

This 2006 report suggests that the US can easily increase its hydropower capacity by 50% but this is stupid since you would go from 6% to 9%. BFD; build more wind instead.

However, the situation in Canada has real potential. A 2010 Report estimates that Canada has 163,000 MW of potential, in addition to the 70,000 MW they already have in production. If all of that 160,000 MW were exported to the US (because market conditions are favorable) that would represent about 20-25% of NET US electrical generation because dams have high capacity factors.

Also, stream flow in canada is subject to less annual fluctuations than in the US. Over the last 20 years, these fluctuations are significant: