A long time ago, back when the romans ruled over Catalunya, there used to be a river which brought life and richness to the surrounding city of Barcino. Birds, reptiles, fish, and mammals roamed freely around marshy wet lands as the river collected its last waters on its way to the sea, cleaning and filtering the water as it went. As time passed Barcino grew, fell, rose, and over again, tuning to Barchinona, Barshiluna, and finally Barcelona. Unfortunately these changes didn’t go unnoticed to the surrounding territory and soon the ecosystem started being reduced, modified, and ultimately transformed. Farm land, flour mills, bridges, and buildings started damaging its natural balance as it gave way to the emergence of the mighty city of Barcelona.

Soon, population expansion and industrialization boosted this growth to unprecedented rates. Modernism and money savvy investors started viewing the marshes and wetlands as a nuisance to development, a barrier to urbanize and bring progress to the ever-growing city of Barcelona.  More and more ecosystem was reduced, from basin to suburb, from ecosystem to park, more and more land was taken for development. As the 20^th century progressed, the time of wars, ideas, modernism, and environmentalism, the basin was ravished, raped, and pillaged turning landscape and ecosystem to a mere straight line on its fastest way to the sea. Polluted and maimed as no other, the river gave its last fight by surprising the city with fast and swift floods. But the massacre was done. The mighty Besós, with its life and diversity was lost, a shadow of what it once was, a scar in the urban trace of the city that caused its destruction.

This unmeasured destruction of the basin didn’t come without consequences for the city though. The deep scar that the river had become disrupted both natural and artificial flows, from one side to the other.  Migration patterns changed, the river became isolated, and surrounding neighborhoods became transit cul-de-sacs, the whole territory became the back alley of the city. Being the ugly duck of beautiful Barcelona neighborhoods, it was doomed to industrial zones and dormitories, scattered with empty forgotten patches. Famed for being a dangerous zone with a dirty river, its existence was doomed to oblivion regardless of whatever changes it undertook.

What started as a simple lagoon soon expanded to take over the city and changed the way we looked and lived in it. The firs system it took over was the city’s water cycle, thirsty for water and nutrients to sustain its ecosystem. What once was the simple action of opening a faucet without knowing where the water came from or where it ended changed completely. Now it was in our faces, in our backyards, and in our life. What used to be hard asphalt and concrete was now full of green, a whole new infrastructure that bypassed the aquifer-building-pipes-disposal system into a natural water cycle of cleaning, filtering, recharging, and bringing life to the once almost extinct Besos marsh ecosystem.

Ever since it started expanding the neighborhood changed. With more things to do and new places to work and live people started staying within the neighborhood. Less cars where needed, the metro brought people instead of taking them away, we were no longer trapped within Mina but integrated to all our surrounding neighborhoods. The new Besos was part of our lifestyle, we no longer ignored it. We cherished it.

As it turns out, the basin we once destroyed was basically an enormous water treatment facility. It treated the water as it swamped and ran through the surface, equivalent to the phytodepuration process. As phytodepuration, swamps clean the water by running it slowly though porous ground while plants – hemp in the case of Besós – take the suspended nutrients in it. Nutrients as DBO, phosphates, and nitrogen among others are used by the plants to thrive and serve as backdrop to a rich ecosystem. The new Besós grew using lagoons, streams, underground flows, and septic tanks, all connected to create patches and corridors that meander through the streets using and integrating existing green areas. All this components combined give it a strong base for growth and different species to roam through it. As the hemp marsh ecosystem matures, its ecological capacity increases and is able to expand its carrying capacity. Given the constant nutrient flow of the city, the ecosystem finds indefinite resources for its expansion.

At first it seemed as if we were losing a battle against the Besós, humans in conflict as always, but we soon realized that these growths where being beneficial to us. As soon as a solid deposition tank reached our building our waste started flowing through the streams, being cleaned along the way until it reached the beautiful and lush lagoons. The lagoons seemed to stop the flow for longer, letting it seep into the water table and back to our homes. With the flow being controlled by the lagoons, it stopped the streams and river from overflowing when the water ran high. It didn’t impair our lifestyle either; we were still able to move around freely thanks to the tunnels it dug as it ran across main streets.

If the streams and lagoons were a surprise, we were dumbfounded when it started growing strange fibers on the empty spaces around the neighborhood. At first we had no idea what it was but soon after we saw that it was hemp fiber that densified, letting more or less light in, grew higher to allow more space inside, sloped lower to let us walk and sit on it, opened more to let us walk freely through it, and fragmented more to allow us to use it in different ways. They changed through time as well, changed the parameters to fit in different uses, evolving and enriching the neighborhood.  Dumbstruck and awed we wondered, how does this happen? Why did it take the path it took? What was making the buildings evolve?

Around the time people started using the buildings we realized that at the time of the first swamp, we got a free app that tracked our movements and let us place the program which we desired around our routes. Within it, it was possible to track the state of expansion of the streams as well, along with statistics of the ecological and carrying capacity of the whole ecosystem.  It was Besós again! It was measuring the water and diversity quality of the ecosystem and using the data received by the sensors that populated its surface to decide when it was possible to expand.  The more its ecological capacity and the richer the diversity of its ecosystem, the more it could grow, the more it needed to expand.  DBO, dissolved oxygen, pH and flow rate of the water, phosphate, nitrogen, and toxin sensors monitored the water quality, infrared camera, motion sensors, sound and image recognition monitored the ecosystem diversity. All the data was summed up and displayed by a light on top of it that indicated the state of its health. A beautiful landscape of green, yellow, or red lights that showed us what happened when we take care of the ecosystem.

At the same time, it received the data we naively placed on the app to guide its growth through and into the city. It overlayed topography to know the route to take, the water usage of buildings to know how much water and nutrients where available, the density of use data to choose its destination, and the different desires of people to grow and change the building’s shape This, orchestrated by its own health stats guided the rhythm of its growth. It took between two and four years to reach enough maturity to expand and another three years till the hemp fibers started growing. Once they grew, it took around 6 months for the first volumes to be created which then where evolved almost daily.

A man once told me that there is a utopic scenario of people dwelling with nature as one, both taking care of each other. A scenario where waste is recycled into nature and given back as resources, a place where animals and plants are as diverse as people’s cultures and traditions, a place shared by all and dominated by none, a city as rich in its tissue as in its ecosystems.  A utopia that is a utopia no more… for it is Besós.