Last weekend, several members of Save Lea Marshes (SLM) joined Gideon Corby of Nature Works CIC, who you may know from the award-winning Wildlife Gardeners of Haggerston, on a fascinating walk along the Hackney bank of the Old River Lea, a Site of Metropolitan Importance for Nature Conservation (SMINC) to discuss the works that his group has been carrying out to rewild the river. We were delighted by the sightings of our emblem bid, the Grey Heron, and the ever-captivating Common Kingfisher on our walk together.
Gideon explained how in the past the Old River Lea has been deliberately widened and straightened and the banks have been raised, particularly with bomb rubble from the Second World War, so that it has become more like a canal than a free flowing river. His latest project, which is supported by the GLA’s Green Roots Fund, with support from the Environment Agency, is designed to improve both the river and the river bank, restoring the river to a more natural flow and protecting and enhancing the biodiversity of the river bank.
The boundary between Waltham Forest and Hackney runs along the middle of the river, with the Waterworks Meadow on one side of the Old River Lea and Hackney Marshes on the other.
For the river to recover, it is important to change the way the river flows by introducing barriers to force the river to meander. The photo above shows a succession of barriers which have been installed on the Waterworks Meadow river bank, designed to push the flow towards the Hackney bank. This will cause silt to collect behind the barriers, slowly building up the bank on that side while the flow will tend to erode the Hackney bank. In some instances water plants will be able to grow, providing shelter for fish and insects, and further slowing the flow of the river behind the barrier.
Over time, as these barriers are introduced along the length of the river, the river should become healthier. The speed of flow in the centre of the river will increase while it will slow behind the barriers, visible in this video. This will cause the river to narrow and deepen. The areas behind the barriers will collect silt and allow water borne insects to flourish, which will encourage small fish, and in turn attract waterfowl to catch the fish. The Old River Lea boasts a breeding population of aptly named kingfishers regularly captured on camera by the talented Kingfishers of East London.
In most instances, natural barriers have been placed in the river to help alter the flow. However, trees also fall into the river as the bank is undermined by the river’s current, achieving the same effect. The eddies and disturbance in the current shows how this affects the flow – with the centre speeding up and the flow behind the barrier slowing down. After the changes introduced as a result of human intervention, the undermining of the river bank will happen naturally over time, eroding the roots of trees, causing them to fall and in turn altering the shape of the river.
Gideon and his team have copied natural processes (in particular trees naturally falling into rivers) and pinned trees in the river to hold it them in place. The trunk is placed at an angle. Over time the way they have copied Nature has varied with techniques finessed. Nature, and its sometime random effects, cannot be copied too closely when working in a highly modified urban river such as the Old Lea. The team don’t cut down trees on the bank close to the river as these trees help stabilise the bank.
Gideon has created a meander with two trees placed near each other on opposite sides of the river (see photo above). He wants to replicate this design further down the river.
Unfortunately, for the most part, as the land has been raised with WWII bomb rubble, Hackney Marshes is not a wetland. With the growing risk of extreme flash flooding it is important to create places where flood water can be absorbed.
Save Lea Marshes argued for the creation of a wetland at New Spitalfields when development was proposed there. While this project is not designed to create wetlands, we hope changes to the river will provide opportunities to plant reed beds along the river edges. During the Olympics the river bank in the Olympic Park was modified and a wetland created. We hope the authorities will be encouraged by imaginative projects like Rewilding the Old Lea to invest in wetland creation projects on other parts of the river.
Nature Works are also working to restore the land on the Hackney river bank to create protected spaces where small mammals and plants can flourish.
The river bank has been badly affected by large crowds of party goers/swimmers and is almost completely denuded in places. Putting in dry or dead hedges like the one in the photo will allow saplings and plants to grow into the hedge and behind it. Several of these hedges have been created along the river bank. In other places trees have been felled to rot and provide food for beetles and other insects which in turn will provide food for birds and mammals. The felled trees also provide barriers to prevent further erosion.
Parts of the Hackney river bank are now recovering so plants, mammals and birds are recolonising the area. You can watch an inspiring short film by Ian Phillips about the incredible recovery of small mammals on YouTube.
These habitat works have been complemented by planting to create much needed habitat and an increased diversity of flora. And in the adjacent area, also with the support of Hackney Council, ReNature London are carrying out widespread habitat enhancement across Hackney Marshes to encourage back species such as Hedgehogs, small reptiles and amphibians.
We’d like to thank Gideon for his informative and inspiring tour of the work that has been done to rewild the Old River Lea. We salute all the hard work of groups such as Nature Works and ReNature London, and applaud the authorities for supporting these crucial ecological interventions. Whilst none of our group are trained ecologists, we have always campaigned to put Nature first, for the sake of both wildlife and people. After all, everyone benefits from a world of increased biodiversity, restored abundance and natural beauty.
If you would like to hear about all the innovative work being done to rewild the river, do join this walk next month!