Next year, if snowpack returns to normal levels, there will be plenty of spare transmission capacity.

FORBES: Connect

In some areas where the constraints are especially acute like Oregon and Washington State, the lack of spare transmission capacity could force wind farms that have already been built to shut down on a rolling basis in the near future.

FORBES: Transmission Bottlenecks Bad News for Renewable Energy

In normal years, snowpack levels are lower and there is spare capacity on transmission lines.

FORBES: Connect

That is why regulators in each country must ensure that there is enough spare generating capacity boffins say perhaps 20% above expected peak load and transmission capacity to be sure the lights stay on.

ECONOMIST: Why do the lights keep going out?