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Monday, 11 September 2017

The reedbeds that are saving the Lea Navigation

After walking the length of the Lea Valley, it was fascinating to learn more about the river from water level, thanks to a Thames21 tour of reedbeds to the north of Bromley-by-Bow. It turns out these reedbeds are a valuable weapon in the ongoing effort to clean up a once highly polluted waterway. I’d seen traditional ones (above), but hadn’t realised what an amazing job they do of reducing pollution: the Lea Navigation is full of toxic ammonia. Reedbeds convert this into nitrate, which is safer – a great way of improving water quality.
The reeds that Thames21 plant aren’t in the actual river bed, but grow in coir matting that floats on the surface, inside a bumper (above). The roots hang down into the water, adding to the surface area. They are easier to maintain than the traditional beds, which can expand to take up too much space. As well as reducing pollution, the reeds oxygenate the river, allowing fish to flourish, and attracting wildlife such as watervoles and birds, including kingfishers and swans.
One reedbed we passed had a massive indentation, where you could see the remains of a swan’s nest – the cygnets now well on the way to adulthood, and probably those we saw out on the water with their parents.
Thames21 is a charity that works with communities across Greater London to improve the rivers, canals, ponds and lakes (see link below). It's already brought 600 m of new reedbeds to Lea, and plans are in hand for more. (Local residents were asked to vote where they should go.) It welcomes volunteers for its many projects, and has a regular newsletter.
Our excursion, on the aptly-named Alfred le Roy (King Alfred defeated the Danes further up the river) took us through Old Ford Lock No 19 (above) before ending at Hackney Wick. The event was part of the annual Thames Festival, which runs for the whole of September. 

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