It happens every year. The Fraser River swells from the thawing of the snow on the mountains, threatening flood damage. You would think that by now, cities and the provincial government would have wised up and set up preventative measures.
The most effective method is to dredge the river, by say two feet deep, all along the river. The soil that is excavated is rich alluvium that can be bagged and sold to nearby farms to partially offset the cost of dredging. If this process had been started five years ago, by now the river would be fully dredged and the flood damage would be history, not current news.
The cost of repairing flood damage is far greater than the cost of dredging. When you factor in the indirect costs (relocation, loss of income, etc.) there is no comparison to preventative measures.
Mayors of the various towns along the Fraser River should join forces to pool their resources and start the dredging process, even piecemeal, so that at least in the reasonable future, such problems are contained or minimized.