Canadians are up in arms about the possibility of the US siphoning off Canadian water. We rail about "bulk water exports", but in reality the US doesn't have to buy the water: they have their own coast lines on the Great Lakes, St Lawrence River, Red River, and so on. All they have to do is divert water in their own territory. In fact, the current low level of Lake Huron may be partly due to dredging in the St Clair River (which has caused erosion that further deepens the river) that is estimated to be causing an extra outflow of 10 billion liters/day.
How we take the water will make all the difference. Obviously, diverting it closer to the sea causes less havoc on communities than taking it in the middle of the continent. But it seems likely that the Great Lakes, with 20% of the world's fresh water, are going to be hit.
The problem with the Great Lakes is that they are not replenished as a river is. About 99% of water in the Great Lakes is a leftover from the last ice age and is non-renewable. Also, the water level goes through periodic up and down cycles, and it isn't known whether the current low levels are temporary or part of a global warming trend.
I live right in the center of the Great Lakes, and for decades we have been exceedingly careful about water usage. It has been ages since you could buy anything but a low-flow toilet in Ontario. In my region residents are only allowed to water their yards or wash their cars one evening a week, after 7 PM. By-law officers enforce the law and hand out fines. By mid-summer most lawns are dormant (brown and dry).
It is therefore not unexpected that southern Ontarians are pretty unhappy about the prospect of the US siphoning off water to US communities - some of them in southern deserts - that do not do much to conserve water. But restricting siphoning is a double-edged sword, and will hurt us too.
Waterloo has plans to build a pipeline from Lake Huron to supply our community with water. Recent concerns about lake levels are raising questions about whether any new pipelines should be allowed. We are already operating with minimal amounts of water. If the new reality means that our pipeline might not happen, we had better adjust our growth rates soon so that we don't get into a godawful mess.
Update: Drought-Stricken South Facing Tough Choices