DROUGHTS AFFECT ALL OF US: Climate change has aggravated an existing vulnerability related to seasonal supply of water in BC. Over time, the safety factor has been shrinking (July 2021)

Note to Reader:

Currently, Metro Vancouver’s source reservoirs can be maintained nearly full under normal conditions from October to March. Snowpack typically starts melting around April, and the reservoirs are drawn down until early fall when the rain returns. ​​Metro Vancouver posts weekly reservoir storage levels from May to October, when rainfall is lower and the regional demand for water can increase by 50%.

Metro Vancouver storage depletion curve as of July 25, 2021, Note that data from 2015 is included, to show impact of extreme dry weather conditions on total source storage.

Lower Mainland edging toward 70-year-old record for days without rain

“As Metro Vancouver heads into Day 43 of drought on Wednesday, officials are asking residents to keep the six-week-long lack of precipitation in mind when they think about watering their lawn or washing their car,” wrote Gordon McIntyre in a Vancouver Sun newspaper published on July 27, 2021.

“The record for no measurable rain at Vancouver International Airport is 58 days.”

Quotable Quote

We’re keeping a close eye on things. The lakes have stopped filling, and we have a finite volume of water we’re working with until we get the next significant rains, typically later in summer or the fall,” said Marilyn Towill, general manager of water services with Metro Vancouver.

To Learn More:

Download a copy of No end in sight for dry spell, which began after Metro Vancouver’s last measurable rainfall on June 15.

A Shrinking Safety Factor

“Climate change has aggravated an existing vulnerability related to seasonal supply of water in BC. Over time, the safety factor has been shrinking. While it rains a lot in BC, we do not have an abundance of supply when demand is greatest. In addition, the mountainous nature of BC’s geography means that BC communities are typically storage-constrained, and what storage they do have is measured in weeks to months,” said Kim Stephens, Executive Director, Partnership for Water Sustainability in British Columbia.

“As of 2015, we clearly crossed an invisible threshold into a different hydrometeorological regime in Western North America. Winters are warmer and wetter. Summers are longer and drier. This new reality has huge consequences for water security, sustainability, and resiliency.”

“A generation ago, water supply managers could reasonably anticipate that three months of water storage would be sufficient to maintain supply during a dry summer. Today, however, a 6-month drought is a very real likelihood, and on a repeating basis. In the meantime, populations have also grown in the major centres.”

Where to Focus Resiliency Efforts

“Because many factors are in play, an over-arching goal for sustainable water supply management would be to build in resiliency that addresses risk. If communities are vulnerable on the supply side, then it would make sense to build in resiliency on the use side. There is no silver bullet. Communities need to do many little things. Over time the cumulative benefits of doing many things do add up.”

“One of the little things that would yield cumulative benefits is requiring a foot of soil for all development sites so that there is a sponge that reduces water need and prevents water runoff.”


The Summer 2021 issue of the Asset Management BC Newsletter includes an article co-written by Kim Stephens and Robert Hicks to open minds about foundational concepts upon which to build climate adaptation strategies that result in whole-system water management outcomes.

To read the complete article, download a copy of Restore the Balance in Water Balance – Climate Change is Another Variable When Planning for Sustainable Service Delivery, Dealing With Uncertainty, and Managing Risk

In addition, download a copy of Living Water Smart in British Columbia: Dealing with Uncertainty and Managing Risk.