Luton is a town that grew up around the source of the river Lea, but you wouldn’t know it today. It’s buried under the town centre, flowing under the cinema, car parks and the mall. In the couple of places where it can be seen, it’s in a concrete channel and more likely to attract litter and shopping trolleys than wildlife.
Many towns and cities develop around a water source, which then becomes more marginal as time goes by. It gets culverted and boxed in, polluted or full of rubbish. This is often worse in developing countries that don’t have established waste infrastructure. Rivers, canals and lakes can get clogged with waste and plastic and become a hazard to health.
Biomatrix Water is a company that develops and provides solutions for restoring urban water. They create floating structures that mimic the natural soft edges of a riverbank, allowing nature to get a ‘toehold’. Over time, the plants take over and absorb them into the landscape. The mass of roots create new ecosystems, filter water and create new niches for insects and fish.
Have a look at their video. I’m sure you know of a town or city near you with a neglected stretch of water waiting for nature to be invited back in.
The Earthbound Report 
When I watched the video I noticed that their floats use plastic to hold the bundles together. I hate putting plastic in water. I wonder if they could use hemp rope?
It is a great idea.
A good point. I expect the plastic holds together for longer without rotting, but that would be something of a compromise.