Each time I have made Green river, I have been struck by the power of the simple change in colour. The vivid green of the non-toxic dye makes the water explicit as it flows past on its way to the ocean, where it disperses and is carried around the globe. This act of dying a river green has been used by others for a number of reasons – by scientists tracing water currents, by the city of Chicago to celebrate St. Patrick’s Day, and by activist organisations like Extinction Rebellion, to name a few. In the art context, the Argentine artist Nicolás García Uriburu dyed the Grand Canal in Venice green in 1968, a work that I learned about after I had created the first Green river intervention. I hope that Green river acknowledges our entanglement in all the constantly changing, yet overlooked, agencies that make up our natural-cultural environment. - Olafur Eliasson