New Podcast Episode: Opportunities in stormwater management

The responsible management of stormwater is essential to protecting our waterways, but it may also present an opportunity to supplement water supply.

For more information check out these resources:

• WaterSMART | A Hazen Company
• Canada WaterPortal
• Alberta Low Impact Development Partnership

Transcript

Host: You're listening to the Land Use podcast brought to you by the Alberta Land Institute.

Laura: Ultimately, all stormwater ends up in our waterways. Being able to manage the quality and the quantity of stormwater can have impacts on the quality and quantity of water in our waterways. When we start to develop land, we start to flatten it out, pave over it, put buildings on it, that results in more stormwater runoff relative to an undeveloped landscape. There's currently no licensing mechanism to say, okay, well, I built this building, I created this much more runoff, can I use that water?

Host: Hello and welcome back to another episode of the Land Use Podcast. My name is Aysha Wu with the Alberta Land Institute.

Today we will be discussing stormwater management, but before we start, I would like to acknowledge that the University of Alberta, its buildings, labs and research stations are primarily located on the territory of the Néhiyaw (Cree), Niitsitapi (Blackfoot), Métis, Nakoda (Stoney), Dene, Haudenosaunee (Iroquois) and Anishinaabe (Ojibway/Saulteaux), lands that are now known as part of Treaties 6, 7 and 8 and homeland of the Métis. The University of Alberta respects the sovereignty, lands, histories, languages, knowledge systems and cultures of all First Nations, Métis and Inuit nations.

Recurring drought across Alberta in recent years has highlighted the need for the province to look for ways to improve water management. The management of stormwater may present a unique opportunity to supplement our water supply, but it is not without its own challenges.

Laura Sandhu, project manager at WaterSMART, a Hazen Company, is joining me today to discuss opportunities and challenges of stormwater management in Alberta. Thank you for joining me Laura. Can you introduce yourself?

Laura: My name is Laura Sandhu. I work for WaterSMART, a Hazen Company. I'm a project manager here and I work in our watershed group, so collaborative watershed management projects. I also support a regional stormwater management project, which I think is the most relevant for our conversation today. I also love biking and hiking and being outside.

Host: Just an outdoor and nature enthusiast.

Laura: Right.

Host: Awesome. So to get started here, could you tell us what stormwater is?

Laura: Right. Yes. Stormwater, in the most basic sense, is water that runs over the ground after it rains or as the snow is melting.

Host: Okay, so why is stormwater management important then?

Laura: Stormwater management is important because ultimately, all stormwater, so water from rain or from snowmelt, ends up in our waterways. Some of it does get absorbed into the ground, but a lot of it does end up in our waterways. So being able to manage the quality and the quantity of stormwater that ends up in our waterways can have impacts on the quality and quantity of water in our waterways. So that can have implications for the health of the river or stream to the health of the ecosystems within the river, the riparian ecosystem. And of course from a volume perspective it can have implications for flooding, and increased flows can cause erosion. Being able to manage both the quality and quantity of stormwater can help us manage the negative impacts of stormwater.

Host: Currently, how is stormwater managed?

Laura: There are many ways in which stormwater is managed and it depends on where you are. It depends on the amount of impervious and pervious surface. So the more impervious area that you have, the less stormwater will be absorbed into the landscape and the more runoff you will have to deal with. So in an urban environment, we have a lot of impervious surface, concrete sidewalk, roofs, so it generates more runoff, more stormwater than you might see in a rural area where you have grassland or forest or even an agricultural field where there's more absorption of stormwater into the landscape.

So in an urban environment, it ranges from really basic stormwater management, like a storm drain and an underground pipe that carries stormwater from wherever it fell, the neighborhood where it, you know, collected into that storm drain and sends it directly to the river. There can be a stormwater pond that basically collects stormwater and holds it for a period of time until it reaches capacity and then it drains to the river. There are also more complex stormwater management practices in urban environments, like bioswales or rain gardens or permeable pavement, that seek to improve infiltration of stormwater before it eventually makes its way to the waterway.

And we can kind of group some practices like that into low impact development, so working stormwater management into planning and development for urban areas. If you were going to plan a new neighborhood rather than having it be, you know roads, sidewalks, parks and just stormwater drains, you could plan it so that you have roads, sidewalks, parks and then maybe a rain garden that helps collect and treat the stormwater before it eventually makes its way in into the waterway.

Host: Okay, interesting. You were kind of talking about this, but how does land use affect stormwater?

Laura: I think in a basic sense, the more development we have, the more stormwater we see because of an increase in impervious area. Undeveloped landscape will have a lot of vegetation, soil, natural depressions, maybe wetlands and that will really help to absorb or at least detain some of the stormwater before it runs off. When we start to develop land, we start to, you know, flatten it out, when we start to pave over it, put buildings on it, put roofs on it, that results in more stormwater runoff relative to an undeveloped landscape.

It also can contribute to change in quality of stormwater. As stormwater runs over roads and sidewalks, it's going to pick up whatever is on that road and sidewalk. So it could pick up salt from the roads that we apply in the winter, it could pick up, like, if there's oil or gasoline from cars. As stormwater runs over, let's say a lawn or a part in an urban environment where there's been lots of dogs out doing their business, stormwater will pick that up. Or fertilizers have been applied on lawns, that's a big one, that stormwater will pick up fertilizer from the lawn. So the quality of stormwater that we see in an urban environment is often lower than the quality of stormwater we would see pre-development. And that's just a function of what it's picking up as it flows over the ground.

Host: What are some of the key challenges faced in stormwater management?

Laura: There are challenges related to quantity and there's challenges related to quality. So when we think about managing stormwater, we try to manage both of those things and often, management solutions that are designed to help with the quantity aspect. So like we talked about detention and retention, slowing it down basically so we're not overwhelming the downstream waterways, oftentimes those management solutions will help improve the quality as well. So holding back stormwater, slowing it down will often help it drop some sediment before it fully relates to the waterways.

When we think of low impact development solutions, those are often also beneficial for both quality and quantity. So when we talked about, you know, managing it at the source, you're managing both the quantity and the quality at the source. And the example of a rain garden, it acts a little bit like a detention pond in a way because the rain garden can absorb and collect a lot of that stormwater and hold it and then it'll, you know, slowly drain and slowly release whatever can't be absorbed. So it helps from a quantity perspective, but also the presence of vegetation within that rain garden has a really big impact on quality too. So the ideal management solution helps address both of those key challenges that relate to stormwater, which is quantity and quality.

Host: Right. That makes sense. So WaterSMART’s looking at potential ways we could utilize stormwater. Do you want to talk about that a little bit?

Laura: Yeah, it's complicated. I'd say that the first thing to be aware of when we think about using stormwater is that it's unpredictable. We can have a general sense of, you know, average annual precipitation that we would see in one year and could make some assumptions around how much stormwater we would expect to see in one year based on an average, but each year is different. Every month, every week, every day is different and that makes it a bit tricky to plan around using stormwater, so it's a little bit like solar energy. If you have, you know, some days that aren't sunny and some days that are sunny, it's hard to plan for, like, continuous use of that input. So planning for continuous use of stormwater is tricky because you don't know when it's going to come, and especially in our climate where we have a winter season and a summer season, we don't see a lot of stormwater during the winter season. I know Calgary and southern Alberta, we have our Chinooks and we can experience a big melt during the winter and then suddenly there is runoff in stormwater. But generally in the winter, we don't see a lot of runoff. So that's the first thing to keep in mind when we talk about utilizing stormwater is it's unreliable, unpredictable and unreliable.

The next question is, okay, well when there is stormwater runoff, could we capture it? Could we store it? Could that increase its reliability a bit like, if you had a battery that you're charging from solar power. So that is possible, to store stormwater. It has its own complications because it requires space. We need somewhere to put all that stormwater. Obviously, the bigger your storage facility is the more stormwater you could theoretically store and use but again from year to year it's still difficult to know for sure that I will have enough storage to store the volume of stormwater that I need to support this use or that I expect to see.

And then the next question that we have to think about is what are you going to use it for? So you can only really count on it during the summer. You could maybe only count on whatever your storage volume could hold and are you gonna transport it somewhere? Because then you need a network of infrastructure and pipes and pumps to be able to move it elsewhere. So what we found in our work and our conversations about the potential use of stormwater is that there could be application to use it on site. So if you had something you could irrigate that was right next to or right close to the pond where you were storing stormwater, then it makes sense to use the stormwater to irrigate, whether it's a park or maybe all golf course, irrigate an area that is proportionate to the amount of stormwater that you think you'd be able to store. So on site, use of stormwater is definitely more feasible than piping it a far distance away and using it somewhere else. So localized –

Host: Right. Kind of like a larger scale version of, like, a rain barrel kind of thing for your yard?

Laura: Yes. Yeah, yeah, yeah. And then, like, I guess the fourth thing to think about, so we have the timing – it's a bit unreliable, unpredictable. The second thing is, can you store it, how much storage do you have? The third thing is when are you actually able to use it? And then the last thing is you know, is there a regulatory framework and at the moment? We have a couple of different pieces of regulation that allows the use of stormwater. So being aware of those is important.

In Alberta, we have the public health guidelines for water reuse and stormwater use, which is still relatively new that came out in 2021. And it outlines the public health assessment that would be required for an application or a stormwater use project where human exposure is likely. So it helps the project applicant understand the process and the assessment that they would need to undertake before they could move forward with the stormwater use project. In 2023, there was an amendment to the Water Ministerial Regulation that exempt water diversions from stormwater ponds up to 6250 cubic meters a year from acquiring a water license. So this is trying to help build, I guess you could call it, a gap. in Alberta where you need a license to divert water and that license is provided through the Government of Alberta. But at the moment we don't have a licensing system for stormwater.

The Crown owns the water in Alberta. That includes the rain that falls from the sky, becomes runoff, becomes stormwater and eventually ends up in our waterways. And the Crown regulates the water. So whether you're using water from the river or you're using stormwater that is flowing over the ground, that is regulated by the province. But the, I guess, the gap in the regulation that we are trying to fill is understanding post development flows. So after you developed the land like we talked about earlier, you can typically expect to see higher volumes of runoff than you would see in an undeveloped piece of land the same size

So there's currently no licensing mechanism to say, okay, well, I've built this building, I created this much more runoff, can I use that water? Can that be my water now, can I get a license to use this way? We don't have a clear framework in place, although we do have processes that are largely case by case where you could make an application to do a project that would use the stormwater runoff being generated in your project location. There are projects that have been approved. There is guidance to help move those projects forward but there's not really that overarching framework to be able to do that yet.
So this exemption for small amounts of stormwater helps to allow smaller projects to use that stormwater that's being generated without having to go through the whole application and receive some sort of approval or some sort of license from the province, so it exempts stormwater diversions from ponds up to 6250 cubic meters a year. For reference, I looked this up, the average annual household use in Edmonton is approximately 160 cubic meters a year.

Host: Oh wow.

Laura: So it's a quote “relatively small volume” when you think of, like, a municipality's water license, but if you think about it from your perspective of what's an individual house using, it’s a good amount of water.

Host: Yeah, that's not insignificant, especially since we're dealing with water shortages and things like that.

Laura: Totally. So it would be helpful in that example that we talked about where let's say a municipality wanted to use the stormwater from their stormwater detention pond to irrigate the field next door. This exemption would allow them to withdraw the water from the pond when it's there, if it's there, and irrigate the field without having to acquire a water license from the province.

Host: So okay, so there's that kind of loophole, but what would you say are some of the main things preventing municipalities from utilizing stormwater right now?

Laura: The devil is in the details with stormwater. Concept level sounds great when you start getting into the details, it's complicated. So we've always had periods of the summer where there's not a lot of rainfall during a drought, let's say this example of the pond and the field, during a drought, your pond won't be full or it won't be refilling, but your field needs water because it's not raining. So the times when you need the stormwater the most are often the times where you don't have any because it's dry everywhere. Yet another kind of complication, it could for sure maybe extend your ability to water that field, maybe a couple of days or maybe a couple of weeks into a drought period, but eventually, you know, there is no more stormwater during a drought. So that's another tricky thing.

Host: So what are the barriers that are kind of stopping us from being able to store water when it's available for times of drought?

Laura: That’s a valid question. The question becomes cost. So, especially in an urban environment, the cost of land can be prohibitive due to creating a large stormwater storage facility. You know, a large pond means a large area that area could have otherwise been used for development, so there's that kind of dilemma of that –

Host: Conflict of land uses, as it often is, right?

Laura: That’s right. In our regional stormwater management project that we're working on to the east of Calgary, we've seen that play out, that trade off between sizing your stormwater pond so that it can handle a large storm event versus, you know, a developer wanting to use that land for their development. And that creates that sort of push and pull between, well, we need to make sure we're managing our stormwater appropriately, but also our developers want to use their land for whatever plan they've got. So that, we've seen that play out to the east of Calgary, striking that balance. And that's where that expertise and understanding of what will stormwater look like in the next five, ten, fifty years? How much are we expecting? How big does that pond need to be? And that's just for straight management, that's not creating a pond for storage.

So maybe that's an important clarification to make is there's an aspect of storing stormwater to slow it down so that we're not overwhelming our creeks and our rivers downstream. So if you think of all the impervious area that the city creates in a rainfall event, over the course of, you know, a matter of maybe a couple of hours or days, you're sending a lot more stormwater to your creeks and rivers than you would have if that land was undeveloped. And so one of the important parts of stormwater management is trying to hold back some of that stormwater so that we're not just, like, overwhelming the creeks and rivers. Because that can, you know, create flooding, it can create increased erosion, it can disturb the river bed and that has impact for creatures. And vegetation that live in the river. So, I guess stormwater management, a big part of it is simply detention and retention, so holding that big first surge and then letting it sort of slowly drain over time.

Host: Absolutely. And I feel like, you know, you did talk about some of it, but what is the future, then, of stormwater management.

Laura: The future of stormwater will be impacted by our changing climate, we can expect to see, I'll use the Calgary specific example because that's where we do most of our work. It's easier to talk, especially we're talking about climate change, iIt's easier to talk about specific examples rather than a broad generalizations, because the impacts of climate change won't be the same base into base in city to city. So in the Bow River Sub-Basin, we expect to see higher air temperatures and an earlier freshet. So that's that, in the spring when the temperature starts to rise and the snow starts to melt, we call that a freshet. We see a lot more runoff and stormwater. Our rivers, you know, river levels go up and that happens all throughout the basin once the temperatures start to rise. So we'll see that earlier in the year.

In Calgary, also expecting to see higher average temperatures and more short duration high intensity storms. So, big storm drops a lot of water, creates a lot of stormwater and that has implications for management. So as we look to the future of stormwater, we have to understand or be able to project what the change is in our climate, how those changes will impact our stormwater, when do we see these stormwater peaks, when are we not going to see stormwater, like later in the summer if we're seeing more drought periods. And if we're seeing more of those short duration, high intensity storms, the peak volume of runoff that we need to manage like that's going to change too. So that's a big part of the future of stormwater is understanding how a changing climate is going to impact stormwater quality, stormwater quantity. And then how do we manage that?

We will continue to get better at managing our stormwater because it has so many co-benefits. Stormwater management is a really important part of the conversation when it comes to watershed management in terms of quantity and quality. So protecting our downstream rivers and ecosystems, source water protection because our, you know, what we send down the river is somebody else's source. So stormwater management can be part of source water protection. Stormwater management is part of flood control, reducing damages from flood stormwater management is potentially important to water security. So if we can figure out a way to use stormwater to supplement our water supply when it's available, that can help offset the water that we withdraw from a river. There's so many co-benefits of stormwater management, and I think that's what I'm trying to express is the future of stormwater management is linked to all of these other aspects of water management that I think we'll see a lot of development in stormwater management in the future.

And current best practices in stormwater management include things like low impact development. So how can we plan and develop so that we're not building so much impervious surface? How can we use things like permeable pavement? How can we use more rain gardens? How can we use green roofs to have better stormwater management and realize all those co-benefits? Though I think the feature of stormwater management includes more low impact development practices, more green infrastructure.

Host: So it really is so much bigger than just, you know, collecting the stormwater but kind of reducing the need to collect the stormwater.

Laura: Exactly. Well said yes. How can we not create so much stormwater because the less you make, the less you have to manage. Because management, like anything else you know, management requires resources and engineering and planning and design. So if you can kind of control it at the source, I guess air quote then that can solve a lot of problems further downstream.

Host: Right, right. That makes sense. So we're nearing the end of the episode here. Can you tell us where people can go to learn more about this topic?

Laura: The Canada Water Portal is a great resource for all kinds of information on water in Canada. It includes information specifically on stormwater. It also has a page dedicated to the regional stormwater management project that I mentioned east of Calgary. People can go there to learn more, the Alberta Low Impact Development Partnership (ALIDP) is a really fantastic group of passionate people and organizations that are working to promote and implement and find research and best practices on low impact development. So I would also suggest folks can look at their websites as well and contact people from that group. They always love talking about low impact development and stormwater. So those would be my top two that come to mind.

Host: Great. Thank you. And before we wrap up, do you have any concluding thoughts or anything you wanted to mention that we didn't get to discuss?

Laura: Maybe a big take away from stormwater in general is that it's localized. So when it comes to planning and management, you know, think local. When it comes to use of stormwater, think local, because it is so location specific in terms of how much you get, what the quality is and how can you use it. Stormwater is local. Stormwater is local, but water knows no boundaries. So there's two aspects to it where, yes, there is that local piece, but it also contributes to the larger watershed and a larger water management system. So everything that you do within that local space is also done within the broader watershed contact.

Host: Alright, perfect. So we will wrap up there then. Thank you so much for joining us. Laura, it was great to have you.

Laura: Thank you so much for having me. It was a pleasure.

Host: WaterSMART’s website and the other resources Laura mentioned are listed in the description if you'd like to learn more. If you enjoyed today's episode, you can like, comment and subscribe. You can also follow us on Facebook, Instagram, X and LinkedIn and sign up for our newsletter from our website, uab.ca/ALI to stay up to date with all of our latest podcasts, research, webinars, and more. Thank you for listening to the Land Use Podcast.