After years of extreme droughts, what’s in store for Vancouver Island’s watersheds?

Vancouver Island University’s Alan Gilchrist is researching how water flows may be affected by climate change.

BY JULIE CHADWICK ● FEATURES, NANAIMO, VANCOUVER ISLAND ● SEPTEMBER 28, 2023

When it comes to water management amidst a climate crisis, even resilient systems may experience challenges, says Vancouver Island University geography professor Alan Gilchrist, who’s in the midst of a six-month research project to study how water moves through the mountains, lakes and rivers on Vancouver Island and how humans use that water.

I sat down with Gilchrist to learn about how several years of long droughts could impact our water levels, how he’s advocating for water-centric policies when it comes to building new developments, and how groundwater aquifers could be at risk if we don’t really know precisely how much water is there and how much people are using.

We also discussed the future of snow on Vancouver Island (hint: the outlook is not great) and whether a warming planet translates to long-term trouble for tree species like cedars.

Read the interview, which has been condensed and edited for clarity.

Julie Chadwick: How is your current research delving into the ways humans use water and how we can better manage it?

Alan Gilchrist: In 2018 and 2019 I developed a model that looked at 12 watersheds around Vancouver Island that does a pretty good job of describing exactly how water moves through the environment — water coming in as precipitation, how it builds as snowpack in the mountains, it fills lakes and moves down through our rivers.

And the systems are very different. Some of them are dominated by watersheds where it rains a lot, like down Island.

Other watersheds are more in the central, higher elevation parts of the Island in Strathcona, where there’s a lot of snow. So that really dramatically changes how water is both temporarily stored seasonally, but also how it just moves down through the watershed.

Part of that project looked at climate change and how the flows may change because of global warming. This semester, I’m really invested in trying to marry that natural understanding of how the water flows with a greater understanding of exactly how humans use water.

The problem with that is that although in some aspects we have a very good handle on how humans use water, that is not the case for many people or many institutions on Vancouver Island. They’re not on metered water, they are maybe tapping into groundwater. It’s a little bit of a black box, and not super sophisticated.

So I’m trying to come up with a general model that will at least put some sort of prediction on that, and look at what is the amount of water that humans are using, how much water is actually available from a pre-existing model and where is the stress being developed in the system — because we know that certain watersheds are getting pretty stressed.

In trying to put together all those pieces, maybe we can be a little bit more proactive about water management and use a more water-centric approach to planning, rather than the kind of situation we see in a lot of jurisdictions around the world, where we tend to use water until we start having problems and then we start reacting.

JC: So ‘here’s how much we have and here’s how much we use.’ How do we chart out how those things come together?

AG: For example, we might have a watershed and say, there is this much water that is available for humans to use, and the rest of it is being used by the natural ecosystem. As humans, we’re supported by the ecosystem, so we can’t just take water from the trees and the animals and the insects for our use or the whole system collapses. Let’s try to figure that out upfront so we can more intelligently develop our communities.

JC: I spoke with Bill Sims at the City of Nanaimo about the water situation, but I am curious about the effects of cumulative drought on the natural environment.

AG: Let’s talk about the drought first, and then about some of the impacts. If you look online, the B.C. government’s been very proactive about publishing a lot of information on things like water levels and drought levels. They have a drought information portal which maps current drought levels in B.C., split by 34 water regions.

Starting around June, when normally we start to see the summer kick in and water levels in rivers or groundwater starts to drop, they rank these different areas according to a classification system where the base level is zero — basically no drought, and then have Levels 1 to 5.

We had a very unusual drought this year, because not only was it very long, but fairly serious drought conditions started in early June. Normally it’s much later than that.

It’s also covering a very large part of the province. There are 34 different regions and 21 of them — two thirds — were in drought Level 5, pretty much all of the lowermost part of the province, Vancouver Island and then bits of the north.

Drought Level 5 means adverse impacts are almost certain on the surrounding ecosystems. This system’s been in place for three years, and we’ve had drought Level 5 in each of the last three years. On Vancouver Island, it’s been every year.

A drought tends to conjure up this idea of something that happens once in a lifetime. It’s a major event, it happens, and then we don’t have to deal with it again. But when it happens every year, I think the reality is that maybe this is the way climate change is now being manifested in parts of B.C.

While this is a very long and unusual drought, it’s probably going to become a lot more frequent, and something we’re just going to have to manage, as part of business as usual.

You mentioned Bill Sims, and I think the good news from a water perspective, is that many of the water managers are very aware of what is potentially happening and the implications of climate change. Some of them have been very proactive or have been fortunate, as explained by Bill, that Nanaimo inherited a system back in the ’90s that is fairly robust and resilient to these droughts.

Ultimately, what we don’t know is, if these very long droughts become more frequent and that becomes the new normal, that may be not be as easy to manage as one that lasts a few weeks.

The other point that Bill made is the fact that some systems are naturally a little bit more resilient. As Nanaimo is using a surface water source and has a relatively large watershed, they can control the height of the dam and how much water they’re actually storing. In any given year, as they see the weather developing and the indications of an impending drought, there are certain things they can do to manage the water supply.

One of the things they really benefit from, for example, is that in many years there is quite a large supply of snow, so that as soon as the summer starts, that water starts to melt, and as they’re drawing from the reservoir it’s continuing to fill for a period of time before the summer really takes off.

Now, other systems — like in groundwater systems in areas where there’s already been a lot of changes to the landscape — there’s very little you can do to proactively manage a groundwater source. If the groundwater levels are naturally low, then there isn’t a way to boost the storage, apart from trying to make changes to the surface environment to enhance the retaining of water in the longer term. There’s a lot of moves now in land use planning to try to do that.

JC: How? Are these groundwater systems more susceptible to climate change’s cumulative effects?

AG: I think one of the biggest things is that we are less sure of the extent and the productive natures of these aquifers. By their very nature, they’re underground, so we can’t see them. The province has a program, because a lot of people are on domestic water wells, that when you drill a well for your property in a rural area as a water supply, that the information is given to the province so they can have some sort of idea what the underlying geology looks like.

And when you have a lot of information in there, you can start to map exactly the extent of these productive aquifers. That’s a great system. But historically, not all individuals have shared that information with the province.

The second thing is if you’re a single residential user, you don’t have to be licensed. Under the new Water Sustainability Act, non-domestic and larger users (250 cubic metres a day or more) do have to be licensed, they have to apply to the province and get a water allocation. But historically, it hasn’t been that well defined.

It’s different with a municipality. Because the City of Nanaimo has a dam in the south Nanaimo watershed, they’re effectively the only user. They maintain the dam, they draw down the water, they know exactly how much water there is, how much is going through their pipe system to the individual homes.

It’s just inherently a lot more well-constrained than a groundwater system, where we have an approximate idea of the size of this aquifer and how much water is down there. But we don’t really have a very good handle on how much water people are extracting, even though they may have a license to extract a certain amount, there isn’t the same reporting. It’s just inherently a system that isn’t well-defined.

JC: So we were heading towards what the cumulative effects are of droughts on the natural environment.

AG: Let’s talk about the ecosystems that are supported by a particular river system. The water that’s within a river normally comes from a couple of different sources. If you have a long period of drought, then you’re not getting water coming in as rainfall. For example, during the winter when it rains a lot around Vancouver Island, a lot of water just flows off across the landscape and it keeps the rivers nice and full.

In summer, you don’t have that, because the summers tend to be a lot drier. So what the natural ecosystem is relying on, because many of the rivers don’t get dry — they’re perennial rivers, they run year-round — is these groundwater aquifers. The aquifers are leaking a little bit of water into the river system and that allows the river to maintain its flow.

That’s what’s known as base flow — water that’s coming in from the underlying aquifer. We had no rain for a few months, but you could still go down to the Nanaimo River or the Millstone River and you’d see that river is still flowing, because it’s coming from the groundwater system.

But part of the problem is that there’s still all these people who are trying to use it as a source of water as well. Whether it’s a domestic user with a well that is drawing out water for daily uses, or farmers who are using groundwater for irrigation.

Continued in PART 2