Are Sponge Cities the Flood Control Fix We Need?

Join Abby and guest John Pattison as they dive into the benefits and drawbacks of "sponge cities," cities that incorporate natural features like wetlands into their stormwater management infrastructure. Is this method more resilient in the long term? Do the benefits outweigh the massive cost? How does this relate to the incremental, bottom-up approach? They’ll cover all this and more in today’s episode of Upzoned.

• Click here for the transcript. (Lightly edited for readability.)

  Abby Newsham 0:04

  This is Abby, and you are listening to Upzoned.

  Abby Newsham 0:18

  Hey everyone, thanks for listening to another episode of Upzoned, the show where we take a big story from the news each week that touches the Strong Towns conversation and we upzone it: We talk about it in depth. I am very excited to be joined today by John Pattison, who is a community builder for Strong Towns, as my guest this week. So welcome John. Thank you for joining us.

  John Pattison 0:44

  Thanks for having me. It's been a while. I think the last time we talked on this show, it was about the proposed Kansas City royal stadium.

  Abby Newsham 0:52

  I think it was, and you know what, that was a long time ago but that conversation is ongoing. So we have not yet landed on a decision for the Kansas City Royals stadium location, and who knows if we'll ever get an answer, hopefully one day. Well, since you haven't been on in a while, I was wondering if maybe we could start by talking a little bit about you. If you want to share what your role is at Strong Towns and your background, and then we can jump into the to the article.

  John Pattison 1:25

  Absolutely, yeah. Thanks for that opportunity. I was hired by Strong Towns in 2019 as our content manager, and so I ran our content for a few years, writing a lot of articles for the site, working with a lot of outside contributors. But in 2022 I moved into a new role at Strong Towns as community builder, and that's what I do today. And so the bulk of what I do is I work with our local Strong Towns groups. We call these Local Conversations. And as of this morning, there are 294 Local Conversations around the world, I used to say around North America, but as of last month, we have our first Local Conversation outside of North America. They started up in Uganda. And so it is one more example of how Strong Towns is increasingly becoming a worldwide movement, which I think is fitting, considering today's topic.

  Abby Newsham 2:21

  Wow. That is incredible. I did not realize that you guys are now starting to connect with folks all the way in Uganda. That's incredible. So are you flying out there and meeting with them?

  John Pattison 2:33

  No, no. That would be amazing. Well, in addition to that one, over the course of the last few months, we've talked with people who want to start groups in New Zealand and India, Guatemala, Colombia, at several different places in Europe, I even talked with somebody in Amsterdam who told me, "The good and the bad coexist here as well. We need Strong Towns."

  Abby Newsham 2:58

  I love that. That's amazing. Well, that's actually a really fitting introduction for today's article, because we are talking about an international piece, although we can bring it back to a multitude of contexts here in the US. I'm very excited about this one. So the title of this article is "Sponge city: Copenhagen adapts to a wetter future." This was published in Yale e360 by Paul Hakanos. Hopefully I pronounced that right, Paul, if I didn't, I'm sorry. So some of the highlights of this article. So basically, in July of 2011, Copenhagen was hit with this huge storm that caused more than five inches of rain to occur in just two hours, so very large amount of water in a very short amount of time, which flooded infrastructure and roads and basements and caused $1.8 billion in damages. This spurred the city to collaborate with a team of urban planners, landscape architects, engineers, to transform Copenhagen into the world's first fully implemented sponge city. So the sponge city model blends both nature based surface features like wetlands and parks with engineered infrastructure, so underground storage, pipes, retention basins, et cetera. And this is really designed to create a situation where you can pretty readily absorb, store and gradually release excess stormwater, an adaptation that is intended to be more resilient in the long term compared to the conventional approach to stormwater mitigation infrastructure. So the city's efforts have inspired other cities across the globe, including Auckland, Singapore, New York, Berlin, to emulate their approach. And another thing that I'll highlight, that I think is really important here is that the infrastructure also doubles as a social and placemaking project, so it blends the functionality with other kinds of goals, like recreation and design. Bike shelters. There's a skate park, an amphitheater, and it all stores storm water while also being a community asset. I'm really excited about this because this is basically the story of a project I worked on in Kansas City, although it's not an entire city like Copenhagen, it's a very small geography. I'm very excited because this is an approach that I think is really needed. It's the kind of thinking that I think is needed. And I know John, you had a lot of questions about it, but I'm excited to hear your perspective on this article as well.

  John Pattison 6:12

  Yeah, absolutely. I was excited to hear that you had worked on a similar project in Kansas City. When you and I were talking about which article we should talk about, the reason I really landed on this one is my daughter just got back from a year long exchange prgram. She did her junior year of high school in Denmark. So for one year, I was hearing about the amazing built environment in in Denmark, and so it was going to be fun to talk about this. I do admit, though, that I'm kind of conflicted about this, and so I'm really happy that you have been working on a similar project in Kansas City, or that you did. Because on the one hand, the project sounds amazing, but it is also a massive project. I think one estimate was $1.3 billion or something like that, well over a billion dollars to do this project. It's going to take multiple decades. And like, the Strong Towns advocate in me is like, okay, let's wait a second. What's the next smallest thing that we can do? But then, what they're actually creating sounds amazing. Do you feel that tension as a planner and as a Strong Towns advocate, or like, are you all in on this?

  Abby Newsham 7:33

  No, I mean, I think that where you're coming from is the right perspective, the idea that you're just going to do this all in one fell swoop is a questionable approach doing this on a city wide scale. I do think for storm water planning there is a city wide perspective to take, because you're dealing with watersheds, you're dealing with impervious surfaces. There are ways to look at it that are citywide. One of the things that I'll mention on the Kansas City project that I worked on was that it's actually an incremental project. So I think it was like $20 million which, in infrastructure world, is not very big. It was the alternative to the 100 million dollar official engineer recommendation for building a pipe and moving water from one place to another, which was the more conventional way of doing it. And instead, what they did was actually use rainfall data, which is what addresses the harsh rains that are described in this Copenhagen article, where you're not talking about situations where it's raining for days and days, you're talking about flash flooding, essentially, where you don't have a lot of time in the equation. And what the project in Kansas City does is it doesn't get rid of all puddling and flooding completely, but it takes three feet of flooding down to maybe four inches of flooding. It makes the area a lot more adaptable. And the underground infrastructure functions both as a storage and transference mechanism, but also the way that these systems are designed is also intended to slow down the pace of water, which is part of the problem here. And so it combines those kind of gray water approaches with the green infrastructure as well. And the thing about doing these kinds of quote, unquote, smaller infrastructure projects more tactically is that they can make really big impact in the right places. I don't want to make a broad statement necessarily, but my instinct is that you don't have to make an entire city a sponge city, and just say, "Hey, we're going to rebuild the whole city and do infrastructure projects like this all over the city, and now Kansas City is a sponge city." I think that it's more so an approach that says, "Where can we make these very incremental, tactical enhancements that soak up water where you're actually getting problems and flash flooding?" Because when flash flooding occurs, it's typically not everywhere. It's typically in very specific areas where water collects because of topography and impervious surfaces and lack of inlets and other things. Also if you have a combined sewer overflow system, which is Kansas City's problem as well. So separating that out is a big impact. So that's kind of my initial thought there. When you look at this idea and think of it as a citywide project, that is a very different conversation than saying, "Hey, how can we think about infrastructure differently, especially with regard to stormwater mitigation? How could we think about it in a way that mitigates stormwater in a reasonable way?" We're not trying to get rid of all water, but we're trying to be reasonable with providing adaptable approaches and apply them in a really strategic way that is meaningful. And then also testing that to make sure that it's doing what it's supposed to do before you go do the next project. So that's kind of my gut feeling on that. Kind of a long winded answer for you.

  John Pattison 12:17

  No, that's really helpful. As I was reading this article, it reminded me of a couple of different things, and I won't get into all of it now. But I remember coming across, years ago, this concept of the permaculture city. And one of the principles of permaculture, to my understanding, is that you don't want water to exit your the land too quickly. And so what this project in Copenhagen does, as you said, it captures the water, it stores the water. So this is good, not only for times of flood, but it's actually important for times of drought, which much of Europe is in right now. And so it does capture that water and keep it from from rolling off too quickly, and makes it usable for the future. Is the permaculture city something that you've come across in your work?

  Abby Newsham 13:13

  I haven't come across that idea, but that does resonate to me based on my experience on this other storm water project. It's not about building a $100 million pipe to shoot the water down to the nearest creek. It's more about how we more meaningfully utilize space in an urban area to realistically mitigate stormwater where it's at and slowly release it back out into the overall system, rather than just shooting it down to the next people and causing impacts that may not be fully understood just by trying move it from one place to another.

  John Pattison 14:03

  Absolutely. It reminds me, one of Chuck's favorite books is, I think it's "Collapse" by Jared Diamond. I actually haven't read it myself, but I've heard Chuck tell the story of how the the farmers in in the Andes had plots of land scattered around the mountain, and experts came in and said, "Well, you know, you could do this a lot more efficiently if you all just collected your pieces of land closer together, and you wouldn't have to travel as far." And so they did that, and what happened is that, when this one piece of collective land had a bad year or something happened, maybe there were insects or pests or something, they were devastated all at once. The benefit of having these different plots across a wide range of areas was that it had this built in redundancy. My understanding of the Copenhagen project is, yes, there are these four massive underground tunnels, and there's a lot of underground infrastructure, but above ground, there's actually a lot of redundancy in all of these different bioswales and parks and parklets and skate parks. And so you do have a lot of built in resilience that I think would appeal to many Strong Towns people.

  Abby Newsham 15:25

  I really agree with that, and I think it's a good way to put this concept of just trying to make a more resilient landscape. You know, the big issue with storm water is just the fact that we've built things in places that were probably not a good place to build on. In the case of the project that I worked on, it was because they built this area of the city on top of a creek back in the early 1900s, late 1800s, and turns out that's probably not a good idea. Water wants to go where it wants to go, and so trying to better align our infrastructure systems with what the earth wants to do, I feel like that's what adaptability and resilience is all about, is just being able to have a city that is in alignment with how physics works and how the earth works.

  John Pattison 16:26

  Yes, I love that. My favorite writer is somebody named Wendell Berry. Friends of mine joke that we should have a Wendell Berry drinking game for John, take a shot every time John mentions Wendell Berry. So here I am, I think we're 16 minutes in the recording, and I'm bringing him up.

  Abby Newsham 16:30

  Everyone take a shot.

  John Pattison 16:38

  Yeah, everybody take a shot if you're listening. Wendell Berry's from Kentucky, so if you have bourbon, that would be even more appropriate. But no, as I was reading this, I was reminded of an essay that Berry wrote decades ago, called "solving for pattern." And Berry is not only a writer, he's also a farmer, and he's been a real advocate for farms, farmers and farming culture for a long time. And I went back and I reread that essay in advance of of this recording, and Berry, in that essay, his primary topic is farming and land use, but his points are, I think, broadly applicable to problems that arise within complex systems. And in that essay, he distinguishes between bad solutions and good solutions. Bad solutions solve for a single purpose or goal, but are ultimately destructive to the larger pattern. Whereas good solutions are good because they are in harmony with the larger patterns. And so he offers up some some guidelines or standards for what he considers a good solution. And I think there are 14 of them, but I'll just mention a couple here. He says a good solution accepts given limits, using so far as possible what is at hand. And he says, the more far fetched the solution is, the more it should not be trusted. And then another one is a good solution improves the balances and symmetries and harmonies within the larger patterns. It doesn't enlarge or complicate one part of the pattern at the expense of the other. And so while there's a lot about this cloud burst management project that I don't understand -- and I don't obviously understand the budget situation in Copenhagen, if they can afford to build and maintain this -- one of the things that I do appreciate is it feels like they are solving for a pattern. Wendell Berry says that a good solution solves more than one problem. You touched on this when you were describing it. This project increases water capacity. It freshens the air. It provides habitat for birds and wildlife and flowers. It promotes biodiversity. It's beautiful, and as you said, it's social too. It's going to bring in more parks and skate parks and amphitheaters. And it's good for times of drought, as much as times of flood. And so, again, it brings me back to this permaculture idea. This seems to be a project that is solving for a larger pattern and is in harmony with the largest pattern, which, as you point out, is nature itself.

  Abby Newsham 19:35

  Wow. That makes me think of so many different things, and I don't want to get too in the nitty gritty of what my experience had been. But you know, one of the things that the team faced in Kansas City on a project like this was that the traditional storm water design standard is focused on addressing the 10 year flood standard, which is not necessarily in alignment with what observed or measurable stormwater events look like. And that was a major barrier, because addressing that 10 year flood, it requires a huge level of investment. It's the $100 million infrastructure improvement that alleviates flooding completely in the worst case scenario event, and the business owners in this area ultimately had to come to the agreement and the understanding that trying to do the moonshot project is maybe less meaningful, but it also is not feasible. They could wait and continue to have properties destroyed and people injured and people losing cars and in these floods, or they could accept the barriers that they're faced with and the limitations that they're faced with, and say, "Is there another option that is more incremental, that alleviates the problem to the extent that we're not going to likely experience massive damage events when we get these flash floods a couple times a year?" And so that was something that really opened my eyes to what the limitations are and how doing something more incrementally can actually get to starting to impact not just one area, but areas downstream. And, you know, thinking of this big picture system of how water flows through a community, right? It's like, there's a lot of tactical things that can be done that is not going to be the moonshot, fixed everything, expensive project. But what if you had a whole system of smaller projects that started to combine to cumulatively address flooding in a very meaningful way?

  John Pattison 22:43

  I think I have an intuitive answer to my question, but you as a planner would know. Obviously, we at Strong Towns talk a lot about the importance of maintenance, replacement, being able to afford that. Is green infrastructure, like what they're describing in this Copenhagen project, less expensive to maintain and eventually replace than the gray infrastructure, or are they roughly parallel?

  Abby Newsham 23:12

  You know, I couldn't tell you that. I don't really know. I have two thoughts about that. My gut instinct is that gray infrastructure is probably more expensive than green infrastructure in terms of long term maintenance, but I don't know for sure. My second thought was that green infrastructure does require maintenance. It's plants and you do need to take care of your trees, and if you have planters and those sorts of things, it's not like you just plant these things once and then never touch it again. There is maintenance that's required, but I think that requires probably more iterative maintenance than, say, an underground stormwater tank that maybe doesn't require as iterative a level of maintenance, but does require maybe more expensive maintenance when those things come due. But again, I'm not an engineer. This is just kind of my gut feeling about what the possibilities may be. It could be very well the opposite, that green infrastructure is way more costly. I'm sure that there's some engineer out there, or somebody who works in maintenance that knows the answer to that. I'd also think that underground storm water probably has a maintenance aspect related to getting debris out of whatever system that looks like, because debris is undoubtedly still going to go through the system and get caught, even if you have filters. So I would imagine that there's some maintenance aspect of that as well. But yeah, I couldn't tell you for sure what would be more expensive.

  John Pattison 25:05

  It is interesting to think about how this project is solving multiple different things and providing multiple benefits to the community. Because if people centered places are ultimately more financially productive, then I don't think it's too much of a leap to say that this project is creating more people centered places that are going to be more financially productive, that would help pay for maintaining and eventually replacing elements of this project itself.

  Abby Newsham 25:37

  Yeah, well that was a big part of the conversation in Kansas City. This was already a very fiscally productive area in terms of its tax revenue per acre. I feel like it's just a non-question that you would want to invest in a place like that. And the thing that, to your point about the benefit of having multiple benefits or outcomes of a project addressing many different things, is that these projects are fundamentally infrastructure projects, and they have a very specific function, which is to address storm water. But that doesn't mean that you also can't integrate placemaking elements into it. If you're tearing up a street, you got to put something back, and it may as well be a better street than it was before. Or maybe you're dealing with a park area, and there's opportunities to utilize a maintenance trail to be a pedestrian walkway, and things like that. And so I think this multidisciplinary approach to these functional engineering projects can be really valuable for helping cities get more out of these projects than what it fundamentally is. I think probably for some cities, when they hear that, they're like, "No, that's going to run the price up. If we start bringing on crazy landscape architects and designers, suddenly they're going to recommend things that don't fall into the scope." But I think that doesn't have to be the case, that you can take this multidisciplinary approach to stormwater infrastructure and find ways to be really smart about how you take functional aspects of that and make them community asset builders.

  John Pattison 27:44

  Yeah, I love that. That's awesome.

  Abby Newsham 27:46

  I'm very passionate about this topic., if you can't tell. I think it's a really cool approach. No matter how small the project could be, I think finding ways to combine infrastructure with placemaking enhancements is a really good opportunity to integrate urban design and good planning into cities in a way that's not just putting together a comprehensive plan or working on a zoning code. There's some really meaningful work that could be done by people who think like planners and landscape architects and other designers, if we could integrate teams with those engineers and work together.

  John Pattison 28:32

  Yeah, it's like the poet Alexander Pope said: "Consult the genius of the place." And I say this as a non-engineer and as a non-planner, but the more that we can do to have our the complexity of our towns and cities in harmony with the laws of nature, I think the better we will all be.

  Abby Newsham 28:54

  I love that. "Consult the genius of the place." That's great. Any other thoughts about this? I mean, I know your daughter spent some time here, and I'm curious if you had a chance to really visit and experience what this kind of looks like because I've never been to Copenhagen.

  John Pattison 29:22

  No, we're actually going in June. So she was with the Rotary Youth Exchange Program, and one of the things that they encourage parents is to not visit during the year of exchange, because it triggers homesickness. But then, if you can, actually go after your child graduates high school and let them be your tour guide. And so we are going in June of 2026. And Molly was not in Copenhagen. She was in the second largest city in Denmark, a city called Aarhus. But we're going to visit both cities as well as other places in Denmark, and she will be our tour guide. I was afraid that, when she saw how amazing the built environment there was, would she even want to come back to the United States? She had a great exchange. She really made the most of it, and she was really ready to come home, which was gratifying for me.

  Abby Newsham 30:16

  Yeah, I feel like going to Europe kind of ruins you, because you come back and you're like, "Why does it look like this?"

  John Pattison 30:25

  That was my experience in Scotland a couple years ago.

  Abby Newsham 30:29

  Yeah, in addition to the jet lag, there's this little depression that creeps in that's like, "Why did I get on the plane?"

  John Pattison 30:40

  The very first thing that she did when she got home was to borrow the car.

  Abby Newsham 30:44

  Oh really? That's funny. Well, yeah, this is really a fascinating project. I'm excited to hear more about it, and this idea of the sponge city is interesting because you're thinking of it as an entire city, but I think from a Strong Towns perspective, we could just think of sponge neighborhoods or sponge districts. A sponge block, a sponge lot. I feel like there's a Dr Seuss book somewhere in there.

  John Pattison 31:22

  Or SpongeBob.

  Abby Newsham 31:24

  I was thinking SpongeBob.

  John Pattison 31:26

  I think that you're totally right. This is a grand project that I think is very inspiring. I think when we see it next year, it will be beautiful. And that grand scale doesn't have to stop us from finding what works for our towns and cities right now, even if that is, as you said, a sponge block or sponge neighborhood.

  Abby Newsham 31:48

  Yeah, totally. I mean, I've been doing my own storm water work on my home property at my house. I didn't really make the connection between the larger scale and what I'm doing just on the lot that I live on, but from a Strong Towns perspective, it's like, what if we as individuals who probably know the stormwater issues more than anybody on our particular property, because we know where it's coming in and where it's puddling in different areas, try to find more resilient ways to capture storm water and move it to areas where landscaping can be. I mean, that's basically what I'm doing at my house, finding ways to have stormwater containment and landscape beds and making some adjustments to topography to try to get it out to the street. So, yeah, I'm creating my own little sponge city on my lot. Unfortunately, that doesn't mean that my neighbors are doing the same thing. But there's probably very impactful things that we could do on individual levels that are in support of an overall sponge city model.

  John Pattison 33:16

  I love that so much. That's great.

  Abby Newsham 33:19

  Cool. Well, thank you so much for joining me today. I guess we can leave it there. But before we finish up today, I want to do the downzone. Hopefully you have one

  John Pattison 33:31

  I do.

  Abby Newsham 33:32

  Okay, I didn't remind you so I wasn't sure if you'd remember. Well, what do you have for me for the downzone?

  John Pattison 33:39

  All right, so I realized a couple days ago that I was reading and loving two books, both of which had been recommended to me by colleagues. One is a book by Anne Cleaves, and in particular, I'm reading her Shetland mystery series that was recommended by my colleague Linda. But the one I really want to talk about, and I'm always years late for this is "the Thursday murder club." I just finished reading the book "the Thursday murder club" by Richard Osman. They're turning into a movie that comes out and later in September on Netflix. It is just an amazing book. It is set in an old folks home -- it's probably not the right language -- in England, and there is a group of four senior adults who meet every Thursday to look at cold case murders and try to solve them. But then what happens is that there is a an actual murder that happens in close connection to their old folks home. The book is delightful and charming. It's also often very tender. The characterization is beautiful and brilliant among not only these four main characters, but this quite large cast of characters. They're very distinct characters. It's very funny without being jokey. And I found myself, long before I was finished with the book, recommending it to person after person after person, because the reading experience was just so delightful. And these folks are older, and so some of their partners are suffering from, like, dementia, and so there's a lot about the aging process too. It was just lovely. I believe that it is a modern classic of the mystery genre, five out of five stars. I just love it so much. And there are a few others in the series, and I can't wait to start book two.

  Abby Newsham 35:48

  Fabulous. Well, that's a pretty big compliment. Who's the author again?

  Abby Newsham 35:57

  Richard Osman, O, S, M, A, N. He has a background in TV. That may be why his voices are so good. It's very delightful. The downzone is always my favorite part of the podcast, because I'm always interested to hear what you're doing, what you're reading, what you're watching. So what's yours this week?

  Abby Newsham 36:26

  Well, actually, I wanted to share something a little bit different and put a plug in for the fact that Chuck is coming to Kansas City again on September 30. I'm really excited about it. One of my friends and mentors organizes a speaker series with the Kansas City Library called Making a Great City Speaker Series, and they're doing basically an installment where Chuck is opening it up on September 30, but it's all focused on housing, and housing as economic development, and really trying to start a broader conversation about housing in Kansas City, alongside many people who are also talking about it. He's bringing in a couple of other people. I think in October we've got AJ Herman from Accelerator for America, Alli Quinlan from Incremental Development Alliance, and Kobe Lefkowitz, who's the author of "building optimism" and an incremental developer. So I'm super excited about this lineup because it's very focused on Strong Towns thinking about housing, and also about incremental development and the role of smaller scale development in this overall picture of housing. Because people kind of think about it as just needing to build giant projects to solve the housing crisis. And this is really about the smaller scale wins that could happen in this picture. So very excited about it. And if anyone is listening, and you're in Kansas City, you should go to the series.

  John Pattison 38:16

  That sounds awesome. As somebody who loves Kansas City, I love that for Kansas City.

  Abby Newsham 38:23

  Me too. I love Kansas City too.

  John Pattison 38:25

  I typically wear my Kansas City Royals baseball cap unless I'm doing something official for Strong Towns. And if this is going to be on video, like, I should not wear a Kansas City Royals hat. But normally, I'm wearing my Royals hat all day long, because I just love that city, and I love that team. Good things are happening in Kansas City. I love it.

  Abby Newsham 38:46

  There's a lot of great things happening. Lot of things that can be done, but there's a lot of great things happening. We just need to decide on a location for the Royal stadium. Any day now, right? Yeah, we need to know. So hopefully we find out soon.

  John Pattison 39:04

  And then I'll bring my family to Kaufman before it's gone.

  Abby Newsham 39:08

  Definitely do that. I've been able to see a couple of games this year and visit Kaufman. And, yeah, it's such a cool complex. It's old, but it's a neat ballpark, yeah. Well, hey, thanks, John. I appreciate you joining me again today, and hopefully you won't be a stranger. We can do this again.

  John Pattison 39:30

  Yeah, I would love that. Thank you for having me.

  Abby Newsham 39:32

  Sure thing. And thanks everyone for listening to another episode of Upzoned. Thanks, John.

  John Pattison 40:12

  Bye.

ADDITIONAL SHOW NOTES

• “‘Sponge City’: Copenhagen Adapts to a Wetter Future” by Paul Hockenos, Yale Environment 360 (July 2025).

• Abby Newsham (X/Twitter).

• Theme Music by Kemet the Phantom.

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