Last Updated: 29 June 2022
We’ve been fielding quite a few questions at the office about water levels along the Lower Fraser River, and to answer these in an efficient manner, we’ve quickly pulled together a post.
As a region we rely on measurements and forecasts of water flows (the volume of water passing by a location) to estimate the level of flooding that will occur downstream. In the Lower Mainland for the Fraser River, the flow passing by Hope is the most commonly used source of information. This is intuitive, the more water there is coming down, the higher and wider the river will be.
However, the Lower Fraser is in a delta, the flat area created by the river as it dropped sediment over centuries and millennia, which means that water levels in the ocean affect water levels in the river. This plays a huge role in water levels in the very low reaches (Vancouver, Richmond, and Delta), and a diminishing role as you go upstream. Because the river is so flat, ocean levels (mostly tide this time of year) affects water levels as far upstream as the Vedder Canal at the border of Abbotsford and Chilliwack (that’s 100 km as the river flows!!!).
Over the next few days and weeks, water levels in the lower reaches of the river will be affected both by the flow passing Hope and by the tides in the ocean. See how below: