[Image: EDAW's "If I could design London, I would... just add water"; view larger!].

With salmon leaping from Sydenham to Southgate and from Hayes to Hackey, the capital's rivers are now so clean that they are teeming with fish and anglers are feasting on London salmon for the first time in around 200 years.

This happy state of affairs stems from Project Salmon, a scheme launched in the run up to the 2012 Olympics to champion pioneering water-sensitive urban design, architecture and public realm design.

All 16 of the Thames tributaries have been brought to the surface once again. Acting as the main arteries for a London-wide water-cleaning system, these waterways are now fed by rain and waste water which is naturally cleaned in a unique network of rain gardens, ornamental channels, reed beds and swales.

Project Salmon has also improved building standards: all new buildings now include innovative designs for green walls, living roofs and integrated sustainable drainage systems.

Many of London's streets now incorporate new watercourses: in residential areas, these channels have become the focus for activities from canoeing to waterside promenading. In Kentish Town the Fleet River has become London's first floating market.

The impact this has had on London's economy and status as a tourist destination is immense. As many other UK and European cities are struggling to manage the annual temperature fluctuations, water shortage and flooding, Londoners have been sheltered from the worst effects of climate change. The success of the scheme has inspired other UK and world cities to follow London's example.

Having been interested in the riverine nature of London for years now – not many people realize that it's a city of canals – when I stumbled on a poster produced by EDAW for an exhibition last summer called " If I could design London I would... ," I was excited enough to print it out and pin it up on my wall here at BLDGBLOG Centraal.Now that I'm moving apartments – again – and have been forced to take the poster down, I decided I should actually write something about it.Using the trope of a fake newspaper article – supposedly published in the Evening Standard in the year 2041 A.D. – EDAW, a surprisingly interesting firm, I might add, write the following scenario. I'll quote the whole thing, in fact, as I don't believe it's been published elsewhere online, and it's an interesting example of fictional narrative put in the service of urban design:The city's buried waterways are returned to the service; roads have becomes rivers; polluted byways are retrofitted into fishing grounds; former car parks find themselves walled off as reservoirs; canals have been reclaimed by the boats of floating markets; roundabouts are overgrown to form wetlands; and green roofs overlook it all.It's idyllic, sure, but it's no mere flight of fancy: the city is surely , over the course of coming centuries . Like it or not, in less time than now exists between us and Shakespeare, our descendants will be living in a London underwater: architects and urban designers – and, for that matter, novelists – might as well start planning now.EDAW's project , and nearly two dozen others, can still be downloaded, a year after the fact, from Building Design