NARRATION: For nearly a century, the waters beneath Seattle's Aurora Bridge have carried a hidden burden—a toxic legacy that threatens an entire ecosystem.

JEN: We know we have a lot of sources of pollution coming from vehicles on the roadways. particulates that get released from the brake wear, from the tire wear, from exhaust particles, different fluids that come out of our vehicles, either leaks or intentional things like windshield washer fluids. There are thousands and thousands of chemicals that come just from roadways alone into our surface waters, and are affecting fish in a variety of ways.

NARRATION: When developer Mark Grey was working from his office next to the water, he noticed something alarming: a large spill that looked like oil.

MARK: Seattle's changed a lot. Some for the good, some for the bad, but we've, we're putting a lot more people on the streets, a lot more cars on the streets, a lot more oil dripping from cars, tire brake dust and whatnot.

MARK: And a lot of that's going into our bodies of water just because of the system we've designed and the way it's built right our systems a hundred years old. it's hard to change that system without digging up streets, and that's complicated.

NARRATION: This isn’t just a story about pollution; it’s a story about transformation. It’s about determined developers, environmentalists, and scientists, who came together to turn a polluted past into a blueprint for a sustainable future.

I’m Brian Maughan, Chief Marketing and Innovation Officer at Fidelity National Financial, and this is Built – where you’ll meet creative leaders in the commercial real estate industry and hear how they’re making a difference.

This season, we’re exploring places where real estate is positively impacting nature. Let’s head to Seattle.

Act I: The Catalyst - History

NARRATION: If you drive through State Route 99, over the west end of Seattle’s Lake Union, you’ll find a cantilever bridge – It’s nearly 12 stories tall and connects the neighborhoods of Fremont and Queen Anne. It’s the George Washington Memorial Bridge, but locals call it the Aurora Bridge.

RACHAEL: So the Aurora Bridge was the first bridge in the country built just for cars. It was finished in 1932, and it's a historic structure.

NARRATION: Rachael Meyer is the director of sustainability and the head of the landscape studio at Weber Thompson, an award-winning, majority women-owned, architectural firm based in Seattle.

RACHAEL: It was the major north-south connection running through the city. Originally it was a way for the train to connect people up to their country homes. And then you know, when development happened, it was this main corridor that ran through Seattle. So it was this major piece of infrastructure.

NARRATION: The bridge, with its towering steel arches, offers stunning views of the city and water as you drive across. The bridge’s roadway and its supports also extend well into the land on either side.

And just beneath the northern end of the bridge is home to the Fremont Troll—a beloved local landmark that has lurked here since 1990. This giant concrete sculpture grips an actual Volkswagen Beetle, as if it had just snatched it from the road above.

Today, we’re heading just 50 yards down the hill from this iconic creature, following Troll Avenue. The area is shaded by the bridge's massive steel structure, and you can see its concrete pillars and steel beams towering overhead.

We’re here to explore a unique collection of gardens known as bioswales. These gardens guide stormwater through vegetation that filters out pollutants—all nestled beneath an over-land segment of the bridge, right under the 65,000 vehicles that cross it daily.

Tour Mark: That's what you're hearing in the background, cars going over expansion joints.

NARRATION: That's developer Mark Grey.

Tour Rachael: It's kind of like a cathedral, like the.. the bridge has these big archways that, you know, just kind of this cool feeling, but we also were thinking of the bridge columns almost like the old growth trees, like they're the same scale of what the old growth trees would have been like here. And so, you know, our trees in the swale are all maples and kind of understory. So it's, it's like the forest floor that we've recreated here.

NARRATION: To better understand why this was necessary, we need to refresh our geography, and go back in time.

NARRATION: Picture the Pacific coast. To the West, Seattle sits on a large saltwater inlet called Puget Sound, which extends into Canada. To the east is Lake Washington, a big freshwater lake with many communities along its shores that are great for recreation. There's also Lake Union, a smaller lake in the middle of Seattle, popular for its iconic houseboats.

For millennia, people have traveled and transported goods around this area, but 200 years ago, this task was more challenging due to the different elevations of the lakes and the ocean.

RACHAEL: At a certain point, it was decided that they needed a physical connection between the water bodies of Puget Sound, Lake Union, and then Lake Washington.

NARRATION: So a canal was conceived in the 1850s, inspired by ancient travel routes used by the Coast Salish people, who encompass many Indigenous nations of the Pacific Northwest.

The project included the Ballard locks, a series of locks that connected Lake Union to Puget Sound, and helped manage the different water levels. When they were closed in 1916, they permanently changed the lake's hydrology.

RACHAEL: Lake Washington used to be nine feet higher[1]. And so Lake Union used to be its own like contained water body and it was all mudflats kind of at the edges. And by creating these canals now they could float logs and they could, allow ships to enter into both Lake Union and Lake Washington from Puget Sound. To think about such a massive reworking of natural water flow is kind of crazy.

NARRATION: And by changing these waterways, the whole ecosystem of the area had to adapt. And here is where we meet those salmon.

JEN: Salmon are actually a really critical component of the food web.

NARRATION: Dr. Jennifer McIntyre is an aquatic toxicologist and fish biologist at Washington State University, in the school of the environment.

JEN: Not only is there a wide diversity of salmon species , there's a whole mnemonic about this, chum, sockeye, chinook. silver or coho and pink salmon.

But they're also incredibly important as food sources for other members of the food web. So primary example would be our killer whales.

NARRATION: And salmon are not only important for the ecosystem, or our plates.

JEN: My understanding based on my interactions with tribal members and tribal leaders is that salmon are so much more than a food source for them. They are economically important to the tribes. They're culturally important to the tribes.

NARRATION: Every year, between June and October, tribes set gill nets near the Aurora bridge bioswales, continuing a millenia-old tradition. This waterway is vital for salmon because they begin their lives in freshwater before embarking on their journey to the ocean. So, these areas allow for select harvesting, a fishing practice that protects weaker salmon stocks while sustaining tribal heritage, the economy, and the salmon ecosystem.

JEN: The babies are born in freshwater, migrate to the estuaries and then the ocean, and then return again as adults.

NARRATION: So in their migration journey, every year, they travel through these waters.

JEN: One of the really important things about salmon overall is that they accumulate all of these marine nutrients. And as adults now they've amassed all of this weight out in the ocean. All of these nutrients and they bring them back to fresh water, where they spawn and then die. That's what Pacific salmon, their life history is that they're semelparous. They only spawn once and they die after they spawn. And as a result of that interesting, biological approach to life, they end up leaving all of those nutrients in that freshwater environment. And that then feeds literally the whole ecosystem, that these salmon come back to, which allows their offspring to also thrive.

NARRATION: But over time, something started to change in this delicate balance.

MARK: My office is about a mile down the road from where we're sitting right now and It's on the water.

NARRATION: Developer Mark Grey again

MARK: We moved our office there over 10 years ago now, and there's a dock, and there's a marine management plan that we had to put in place that if a boat leaked, here's what you need to have your spill kits and all that in one day we came down and there's a huge slick on the water. You know, you saw it and you're like, Oh my gosh, one of the boats is leaking oil and we ran down with our spill kits and we came to find out that it was just stormwater coming off the street…

BRIAN: Oh my goodness.

MARK: …in the lake that was creating this oil slick and shame on me for not understanding that there's no like real filtration system off our streets. It just goes straight into the body of water.

JEN: You know, 25 years ago, we became aware that coho salmon in particular were dying in the fall when they were coming back to spawn. certainly we have a lot of challenges in Puget Sound watersheds related to physical habitat, just the availability of spawning and rearing habitats. But in addition to the physical habitat, there's the chemical habitat to consider.

NARRATION: And that's where Jen's research has been critical. Her lab focuses on stormwater pollution and other chemical mixtures that get into the environment and cause problems for aquatic animals. Particularly on the Puget Sound.

JEN: Most of that research ends up being focused on stormwater runoff. And this is the collection of water and chemicals that come with it, that enter into surface waters, that's rivers and lakes, the ocean, from built up environments. So from our roads, our sidewalks, our roofs, our vehicles.

NARRATION: And the numbers don’t lie.

MARK: Army Corps of Engineers count the number of fish that go through the Ballard Locks every year. You can go look it up right now. as recently as 2006, 453,000 salmon went through the Ballard Locks. In 2017, we had 129,000 salmon go through the Ballard Locks. In 2022, this is the latest data I had at the time, only 43,000 thousand salmon I'm rounding went through the Ballard Lock.

NARRATION: And in 2023, only 23,901

MARK: So that's a problem for the whole ecosystem and ocean and everything else.

JEN: Over the decades, we were able to make an association to stormwater runoff. Okay, it's something coming into these streams where the fish are trying to spawn when it rains. We eventually were able to narrow it down to something coming off of roadways through our experimental studies.

NARRATION: After the incident at Mark's office, he and his team started asking around, and they found a video from Jen's lab – about tires.

JEN: Like on docks and on, on boats sometimes you'll see tires that are there to protect the boat or protect docks and stuff. At that time I was just using like a chunk of tire, very simple experimental design: tank with water, add chunk of tire, add fish, fish are all dead the next day.

NARRATION: Chemicals in tires have proven to be extremely toxic especially for Coho salmon. And that's documented in the video Mark and his team watched, which added to their belief that they needed to do something.

JEN: The other thing that I feel like people wouldn't know is that the water doesn't look any different with this chemical present in the water. And so in the case of stormwater runoff, there's a lot of things making up that mixture. And you do end up getting a water that looks dark and murky. But you don't need that to have the mortality that takes place with the fish. Just this chunk of tire alone in a tank full of fish causes them to die within essentially just a few hours. And that's something I think people sometimes don't understand when I'm talking about this research is how very acute that mortality really is.

MARK: The salmon are migrating in September. Guess what happens in September in Seattle?

BRIAN: Starts to rain.

MARK: Rain. We're dry right now. But we're gonna get a big flush of rain, probably in September. And if it's been dry for three weeks, that water is the worst water because it's that much stuff has been sitting on the streets. But that's when our salmon are migrating. Yeah, so, it's even worse. And so they're swimming through this toxic cocktail on their way to create more fish.

NARRATION: Around the time Mark and his team became aware of Jen's research, they were working on their own development project; it turned out to be the perfect testing ground for designing green infrastructure to help clean these waters.

CUES: Seg B - Act II: The Transformation - Teams get behind the idea - public-private partnership - the buildings/phases I, II and III

Tour Brian: Right now we're on North 34th Street, which is going perpendicular to the bridge.

Tour Brian: We're under the bridge, and if you look across, we can see Lake Union, and Lake Union has got these beautiful boats everywhere. You've got the hill of Seattle right there. And in the distance I can see Mount Rainier.

NARRATION: Mark is a Seattle native. He is a partner at Hess Callahan Grey Group and also serves as Principal at Stephen C. Grey and Associates, the commercial real estate company founded by his father.

MARK: We talked a lot about what do we want to do? And Lisa Picard, she's a well known real estate professional. She said it best. She said, you got to give a shit. I truly believe in that. And so we really focused on projects that we can be proud of, but we also believed that the community would like. Especially in this environment right now, we always felt that if we build something that's nice, and the world goes to crap, and the office market's not great right now, and people have a choice, they're going to choose our building over the building across the street.

MARK: It's fun to create something that people want to be in.

NARRATION: If you stand at the intersection of Troll Avenue, you’ll notice two sleek, modern buildings, one on each side of the bridge. These were developed by Mark and his partners at Hess Callahan Grey Group, in collaboration with the architecture firm Weber Thompson. The bioswales were integrated into the construction of these buildings.

MARK: Thank God I have great partners. They were like, yeah, this is great. Because everyone asks, how much did it cost? I'm like, I don't know. We baked it into the project. We just think this is the right thing to do.

NARRATION: The first building, completed in 2017, is an office building called Data One; that became Phase 1 of the bioswales project.

MARK: That's a 130,000 square foot building,

NARRATION: The second project and phase 2 of the bioswales, is the Watershed building.

MARK: That's a 60,000 ish square foot building, directly across the street. And the Aurora Bridge divides both of those.

NARRATION: From the bridge, Data One is to the West and Watershed is to the East. And the team made the bioswales part of the construction process in both properties. We met with Mark at Weber Thompson’s offices inside Watershed; it happens to be one of Seattle's most sustainable buildings.

MARK: And we're sitting about 50 yards away from Lake Union, same lake where my office is on, and same route that the salmon spawn on. And so, if you go back and look at, that aha moment, we were starting to build that first phase. And we were talking about this problem, and said, is there anything we can do in terms of cleaning up the water as part of this project?

MARK: What we found out is, we are not combined sewer overflow here. We are just stormwater. And so our civil engineer said that water that comes off the Ore Bridge is pretty dirty. And why don't we build some bioswales?

RACHAEL: At the time, Seattle hadn't created its very progressive water policies.

NARRATION: Weber Thompson's Rachel Meyer has been part of this project since the beginning.

RACHAEL: And so everything that was done on both Data One and Watershed predated those policies. So it was all very voluntary and elective. And it was to solve the problem that the condition under the bridge was dirty, it was black. And we wanted to establish this vibrant commercial corridor.

BRIAN: Be honest with me. Did you know what a bioswale was before this started?

RACHAEL: Yeah. Yeah.

BRIAN: I had to look it up.

RACHAEL: Yeah. That is a, you know, a landscape term.

BRIAN: Okay. I'm just wondering. Yeah. All right.

RACHAEL: A lot of people use the word ditch. It is a ditch

BRIAN: Well then why can't you just talk about that? I know what a ditch is. I grew up with ditches.

RACHAEL: Yeah. Everybody knows a ditch.

NARRATION: Rachel grew up in the other Washington – D.C., but once she came to Seattle’s University of Washington to study land architecture, she never left the state.

She’s been focused on sustainability her whole career. Even before joining Weber Thompson, she had worked on a number of green buildings, including the Bullitt Center, one of the largest "net positive" energy buildings in the world. So she was more than ready to tackle the challenge of creating bioswales.

RACHAEL: Landscapes have been doing this forever. You know, the easiest way to manage water is to funnel it into an area. And if you have the space on your site, it's very easy to do.

NARRATION: The two new buildings -which are on private land- included space right under the bridge, which is owned by the State of Washington. So we’re talking about state water – technically – because rain lands on the bridge, then it drops onto the city of

Seattle roads in front of these 2 private developments.

The bioswales clean the water that comes down from the bridge via downspouts. There’s 1 in Phase 1, 2 more in Phase 2, and Phase 3 added 5 more that bring water from the center of the bridge. 

Previously, the city's system sent water straight from the downspouts through an infrastructure pipe directly to the lake. Now, the water from these 8 downspouts runs through the swales first before connecting to the same old pipe that outfalls at the lake edge.

All 3 phases combined manage more than 2 million gallons of stormwater every year.

RACHAEL: So it was this like simple premise that natural systems could address the problem. We were going to just divert this water temporarily, run it through soil, and put it back in the same pipe. And that was really important from a process standpoint because it had to stay that simple in order to get so many jurisdictions to agree to let us do it.

BRIAN: But no one, the city wasn't asking for you to do it. It wasn't that somebody came to you and said, hey, if you're going to take this lot and build this Data One building on it, you've got to accommodate for… this was just conversation of the project owner.

MARK: Let's do it. Yeah. And, what's really interesting Brian is that, you know, we first started talking to the city, and the answer was no. Everyone says we want to do green things, but part of the hard part is that the Aurora Bridge is state freeway.

BRIAN: Okay.

MARK: And then the sidewalk that we were talking about converting just from asphalt into these these bioswales was city right of way.

NARRATION: In commercial developments, there’s usually a right of way or public area in front of the building—between the sidewalk and the structure, where you often see plants or art.

And so they were like, you can't take state water. And then put it into city right of way done by a private developer, clean it, and then discharge that same water back into the city system and dump it in the lake.

MARK: You can't do that. And you're like, why not? No, that's, and there's a lot of legalese with state, city, Department of Fish and Wildlife, you're tapping a lot of different jurisdictions that need to nod their head to say yes to that first one down spell. And. We just kept saying, why not? Why not?

BRIAN: So what unlocked it?

MARK: I think a lot of persistence. A lot of persistence.

NARRATION: And that persistence, eventually got Seattle Public Utilities interested, and the project moved forward.

MARK: We basically donated all the infrastructure we built because it's on a right away and said you guys can have it. We're going to build it. The landscaping we want to maintain, because, sorry to say this about the city, they're not going to maintain it. We'll take care of the graffiti, if a plant dies. We want it to look good, but we'll donate the infrastructure to you, and we did that.

NARRATION: They even drafted an agreement outlining responsibilities, which became the blueprint for the next phases.

MARK: We have a great relationship with SPU. We're really excited about what we've done.

NARRATION: Before these projects, the area under the bridge was just asphalt, grass, and graffiti—a perfect canvas for new green infrastructure. And this canvas had some unexpected extra space.

RACHAEL: The city has its standards for what that needs to look like. The unique thing was, because of the bridge, there was an extra wide right of way. So usually we have 12 feet ish to work with. We had 19 feet.

RACHAEL: But it was also extremely steep. So this design, which was a collaboration with KPFF, our civil engineer, this was one of the unique aspects of the project. There really hadn't been such steep bioretention planters proposed this way before.

Tour Mark: For phase one and phase two, we're pulling both these downspouts to the below and just letting gravity do its thing.

NARRATION: Under the bridge, Mark points to long metal pipes that run vertically down the bridge’s concrete pillars.

Tour Mark: Downspouts run along the Aurora Bridge column that, I don't know, how many feet do think that is? Four stories up? [Yeah.] It comes down through this concrete.

NARRATION: Mark shows us the path the water follows on rainy days, starting from the downspouts on the bridge. Instead of flowing directly into city pipes and towards the lake, the stormwater is diverted through an outflow system that guides it to street-level.

Tour Rachael: You can see the outfall there is that pipe that's coming out of the ground.

Tour Mark: And outfalls right here, goes into this catch basin…

Tour Rachael: And so those catch basins are where the sediment is kind of settling out before coming into the swale.

Tour Brian: Oh, ok.

Tour Rachael: And so the city comes through as part of their maintenance responsibility and vacuums that sediment every year. It's kind of the main maintenance activity other just tending to the plants and making sure everything's growing.

NARRATION: Then, the stormwater runs down the hill 30 yards and enters the bioswales.

Tour Mark: And that's where you'll first see the water come through.

NARRATION: You can picture these bioswales as a series of terraces, that the team calls cells. In this phase, phase one next to the Data One building, 6 cells cascade down a gentle slope, each one sitting about 2 feet above the next.

Think of them as long, natural steps. When it rains, these terraces catch and filter the stormwater, helping to protect the lake.

At the moment, we are looking at the first one.

Tour Rachael: It has a clay liner underneath it. So it's not infiltrating into the ground, because we didn't want to undermine the bridge. All of that water is staying in that planting area, and each one is a couple hundred square feet. So, it's about 10 feet wide, half a block long, between the alley and the next street down the hill.

Tour Mark: So the water that hits this first outfall is untreated.

NARRATION: Today is a sunny day so there's no water, but Mark says that when it rains, the stormwater at this point looks black as a cup of coffee.

Tour Mark: And when that water cascades down through that first cell, nature's doing its job and cleans it.

NARRATION: The water enters the top of the cell, then gradually soaks through. At the far end of each cell, there’s a steel wall called a weir, which has a rustic, weathered look. These weirs have a small opening in the middle, known as a daylight, that allows excess water to flow into the next cell when needed.

Within each cell, you’ll find soil, rocks, and plants that work together to filter and clean the stormwater as it moves through the system.

RACHAEL: You'll see that there are a lot of flowering species of plants and that was definitely intentional because it's just lovely, it's part of what creates a character. But, Watershed is also a living building. And we have four beehives on the roof. And so the plants also support the bees. And so you'll see that there's kind of small pools of water that the bees are coming to because bees need water to drink as well.

NARRATION: The stormwater gets cleaned again and again at each step. Rachael says that initial tests showed that at least 70% of contaminants were removed after just the first cell.

RACHAEL: The swales worked so well that the water didn't even make it past the third step the first year. And that is the other kind of cool thing about swales is they're like big sponges, and the soil will just expand and hold that water. And so in addition to cleaning it that first year, it meant no polluted water at all reached the lake. And that's really what you want.

Tour Mark: Should we walk to phase two and then phase three?

Tour Brian: Yeah, let's do it.

Tour Mark: We are standing outside the watershed building on Troll Avenue. We called this phase two, and we just said let's up the game, did two downspouts, and alley water and some building water. So now we're at phase two, and there's two major pipes coming into the first bioswale at the top of the hill at the watershed building.

Tour Mark: One is the Aurora Bridge downspout, and the second pipe is the alley’s water coming right here. And so really, right at the top, we're commingling two water sources that probably have different levels of toxins in them. The bridge is going to be worse than the alley water, is the hypothesis. But look at the rocks. Look how dirty the rocks are then look one cell down, and, it’s not a glass of water that you're looking at, but the top the rocks are very dark gray, almost black, and just one cell down, they look like right off the beach.

NARRATION: You might think that with all the pollution filtering through these cells, you’d need to change the elements on the cell, like you would with an air purifier—but that’s not the case.

Tour Rachael: So the, the chemical does have a half life, and so over time, it breaks down, and a lot of people want to know if the soil is now toxic, right, because it's taking up all the stuff. And that's another beauty of nature is the soil is alive with organisms, and that is breaking down anything that's made of petroleum, any other toxins get either broken down into a safe form or taken up by the plants. And so we don't have a situation where the soil is just getting more and more toxic. Nature's just doing its thing and helping to manage that.

NARRATION: Rachael says phase 2 also ‘upped the game’ from her standpoint..

RACHAEL: When we designed Watershed, we had a biomimicry charette at the beginning of the project.

BRIAN: A biomimicry charette.

RACHAEL: Yep. Biomimicry is using principles in nature to design. Nature really has figured everything out.

RACHAEL: We just need to harness that knowledge and apply it to our designs. So we explored what aspects of the ecosystem were not present anymore, because it was this built-out urban area, and tried to restore some of that function. So in Seattle, one of the main ecosystem services, is what we call it, that is no longer present, is evaporation. In a forest, the trees and the soil would capture almost half of the rain that would fall in the area and it would never reach the soil. And so the fact that we don't have that tree canopy means that function isn't happening anymore.

RACHAEL: So our goal was to try and find ways to hold onto the water and evaporate it, to try and reach the same function that the forest would provide. And so we built these shallow steps that have some bronze weirs, and those shallow steps give the water the slowest path to travel, and they join up with the swale ultimately, but the goal was to just allow that water to linger and evaporate and restore some of that natural function.

NARRATION: We made our way south to the next stretch of the bioswales project, down the hill, closer to where the land meets the lake.

Tour Brian: Ok, so this is Phase three.

Tour Rachael: This is phase three.

Tour Brian: Still underneath the bridge, about a block down from the Data One and the Watershed building and we're probably within a hundred yards, less than a hundred yards, to the lake.

NARRATION: About 50 more yards ahead, underwater, is the outflow of the system, so the final piece of infrastructure brings whatever water is left into the lake. And near here is where the tribes gill net in the fall.

Tour Mark: We're looking 20 yards north, there's a Aurora Bridge column with a downspout, and you can see that downspout curves into a catch basin. We installed that catch basin, and in the middle of the roadway you can see where concrete was cut out and there's new asphalt put in. That's the pipe bringing the water to our phase three.

RACHAEL: We don't have the grade change that we did on the first two phases. So we had to come up with a different strategy.  So we created a trough. We have capacity for up to five downspouts to enter this system from both ends of this trough and the water comes in there and allows all of the sediments to settle out. And, intentionally, we have a bunch of river rock in there. And when it's dry, it's black and it's a big contrast with the river rock on the other side of the weir, where the water overflows and goes into the planting area. You can see the difference.

NARRATION: In this phase, the weir walls are designed to guide the water along the longest possible route before it reaches the outflow, maximizing its treatment. There are five cells in this section, and each weir wall features a distinctive downward-turned corner.

Tour Rachael: We carved out silhouettes of each of the five salmon species that swims under this bridge. So if you look, kind of, of from the south, looking north, you can see each of these salmon’s shadow reflected on the steel wall. We rarely see water in the planting area in this cell. You easily see the trough fill up, but the water moves very slowly. And so it really doesn't become standing water, but it just slowly kind of moves towards that outfall and gets a good amount of treatment.

7 NARRATION: Now, remember that Lake Washington’s water level was lowered around the time the bridge was built? So this area, where phase 3 is now, was underwater many years ago.

Tour Rachael: These columns used to be standing within the lake, and they're actually supported by dug fir trees that were embedded in the lake bed. And that's what's holding up this bridge. And then when that lake was lowered, Lake Union's level was also lowered a little bit, and this became land that could be developed.

NARRATION: The land for phase three is now private property. It's a ground lease to Fremont Dock Company, which today is part of the Owner's Association that Mark and his team manage.

MARK: There's the Fremont Bridge, which is a quarter mile away. And there's seven buildings over there. And the tenants of those seven buildings are Adobe, Google, Path, which is a nonprofit that funds cures for malaria across the way, those are across that area. We manage that owners association and that ground. We said, hey everybody, if we can raise the money to do a bioswale on this property, in this dirt, with all these different ownership groups, allow us to do that. And they said yes.

NARRATION: Securing the necessary funding was another challenge, but with a clear vision, they were able to make it work.

MARK: First phase was privately funded and Each of the buildings we've done have been different LLCs, different partnership groups.

MARK: So the first phase was HessCallahanGrey Group and HAL Real Estate. Spear street capitals is our partner on the building we're sitting in right now out of San Francisco.

MARK: And then phase three, that's ground lease property.

NARRATION:  And Mark has partners in yet another group—this one focused on nature: Clean Lake Union, a non-profit committed to saving salmon and revitalizing polluted waterways in Seattle, is one of the driving forces behind all these efforts.

MARK: And the nature conservancy got involved in this phase and helped us raise 500,000 from the state. And then we also had the Boeing Foundation gave us some money to do that as well.

MARK: And then we do an annual paddleboard race, to raise money. And so we got all that money pulled together and funded that third phase, which basically we're treating the north half of the Aurora Bridge, and all the water that comes off it. And what's so cool is that's a replica model. There's bridges all over the world

CUES: Seg C - Act III: The Expansion and Legacy - Phase 4, this is just a drop of water but there’s hope.

Tour Brian: I don't know, I just never would think that being under a bridge would be this appealing. But it's actually very gorgeous.

Tour Mark: It's an area now that the city community love and enjoy. We got benches that are surrounding our bioswales where people are sitting and eating,

NARRATION: There’s bikers, joggers, even swimmers and fishermen, taking advantage of the water that the Aurora bridge bioswales are helping clean.

Tour Rachael: The city is actually putting money towards incentivizing this on other projects. And this was project that showed that it could be done and that it, wouldn't open, kind of, a can of worms of all these problems. It really is solving problems and public is benefiting from it.

NARRATION: The city's support has been so strong that the efforts have extended beyond the Aurora Bridge. In fact, the bridge’s bioswales became the blueprint for a new project that opened in August 2024: Northlake Commons, a mile down the road to the east.

The Northlake Commons bioswale treats over 2.5 million gallons of stormwater each year, surpassing the capacity of all three phases at Aurora Bridge combined. Unlike the Aurora project, which focuses on water from the bridge, Northlake's bioswale will manage stormwater from surface streets.

NARRATION: And remember professor Jenifer McIntyre? While the Aurora Bridge bioswales were being built, her lab kept studying the stormwater.

JEN: We've learned that there are more than 2, 000 chemicals that come from tires and get into our waterways. And lo and behold, we were able to discern that it was a chemical no one had heard of before. So it's called 6PPD quinone. And some of the early legislative interactions we had were asking us, should we just ban 6PPD?

JEN: And we're like, hold on, hold on. That's a little too hasty because it turns out that this chemical is used in tires very intentionally. It's the reason that we have tires that can last 50, 000 miles now.

NARRATION: Turns out, chemicals like 6PPD are added to tires to stop the rubber from cracking when it comes into contact with ozone that's already in the atmosphere.

JEN: Your tire can blow off right while you're driving. So, a safety concern for those of us driving vehicles.

NARRATION: Jen says that 6PPD is at the top of the list of the most toxic chemicals we know for aquatic life. But we're not powerless.

JEN: It's really important that people advocate for these large scale solutions. So the fact that we've got these bioswales under the Aurora Bridge treating a really large volume of stormwater is way more impactful than what any group of individuals could do in their daily practices.

JEN: Ultimately though, we may find that we simply can't put enough green infrastructure in place and we do need to pay more attention to these source controls, um, replacing that chemical. There is an international search on for a safer alternative to 6PPD in tires to fill that role.

8 NARRATION: It's still early to gauge the full impact of the bioswales on salmon populations, but these green spaces under the Aurora Bridge are already making a difference—cleaning 2 million gallons of water each year. The bioswales have also enhanced the urban landscape, earning several accolades, including the prestigious "Urban Land Institute's Awards for Excellence."

RACHAEL: Right when we finished construction of Watershed and the second swale, we had three inches of rain in the matter of just a few hours. And it was amazing to watch the volume of water going through this infrastructure.

NARRATION: But the bioswales aren’t just about water—they're about the entire ecosystem, with salmon serving as an indicator species. If the salmon are struggling, it means the whole ecosystem is in trouble.

RACHAEL: They directly impact the health of orca. And it's because the population of salmon has declined so much, the orca are starving.

NARRATION: The impact of this decline was felt deeply just a few years after the project started, when a mother orca carried her dead calf for 17 days, a heartbreaking symbol of the urgent need for change.

RACHAEL: This is easy to do. It's very cost effective. Clearly, you can do it in an urban center, and that's the most concentrated areas where are these pollutants coming together. And the goal is to clean six bridges.

Tour Mark: And there's what, 23 street ends on Lake Union alone, where there's opportunities to do bioswales. And usually a lot of the city infrastructure, that's where the outfalls are, is next to those street ends.

NARRATION: The greatest reward, Mark says, will be when building bioswales becomes easier and more widespread.

MARK: The city of Seattle has a consent decree that they need to keep the water clean, and so we're helping them do their job. If we can figure out and not make it too bureaucratic of how people can do this as part of new development, where there's an incentive. Good for the environment, good for the developer, good for the city, good for everyone. That's where it's going to work.

MARK: We'll continue to do it, but I'd love to see others do it. You can do it at your house, right? Take your roof water if you want, and use it for irrigation. It just doesn't have to be this 200,000 square foot building that needs to move this forward. Anyone can do it.

BRIAN NARRATION: If you want to check out videos and photos of the Aurora Bridge bioswales visit us at builtpodcast.com. Built is a co-production of Fidelity National Financial and PRX Productions. From FNF, our project is run by Annie Bardelas. This episode was produced by Sandra Lopez-Monsalve and edited by Genevieve Sponsler. Production support by Livia Brock. Audio mastering by Rebecca Seidel. Our location producers for this episode are Neroli Price and Steve Jackson. The Executive Producer of PRX Productions is Jocelyn Gonzales.

Special thanks to our guests, and to Barbara Gering and Jennifer Primm. I’m Brian Maughan. Thanks for listening and remember, every story is unique, every property is individual, but we’re all part of this BUILT world.