The ecology of Walthamstow Wetlands

Birds flying over Walthamstow Wetlands by Greg Morgan

Walthamstow Reservoirs are a complex of ten large water bodies constructed between 1853 and 1904 by the East London Waterworks Company (bar Lockwood, constructed several decades later). They have been an integral part of London’s water supply ever since.

Positioned in the heart of the Lee Valley, the site is highly important for biodiversity, and in particular a wide range of bird life.

The 211 hectare site is designated as a Site of Special Scientific Interest (SSSI), on account of its national importance to migratory and wintering waterbirds, particularly shoveler, bittern and gadwall – but also breeding grey heron, cormorant and tufted duck.

As well as being granted SSSI status, the reservoirs are entirely within a Special Protection Area (SPA) and are a RAMSAR site (particular for the presence of shoveler, gadwall and bittern), both indicating the international importance of the site – perhaps more so given its urban context.

This status also gives the site legal protection, ensuring its qualities are maintained as they are today.

The Reservoirs also form part of a larger Site of Metropolitan Importance for Nature Conservation, for the mixture of aquatic and terrestrial habitats they provide, and for their London-wide importance (especially for birds).

Thames Water, the owners of the Reservoirs, has contributed positively to the value of the reservoirs in two ways:

First, by offering limited recreational opportunities to permit holders in the shape of anglers, naturalists and other visitors.

Secondly, and most importantly in this context, by maintaining both the site’s wildlife and aesthetic value – achieved by conforming with sympathetic management regimes – thus providing foundations for future habitat improvement and enhancement.

Nevertheless, the Reservoirs have been and are barely utilised by the vast majority of local people, largely because of an almost total lack of awareness of the site, limited accessibility, lack of facilities and activities, and little community involvement.

This has resulted in an almost non-existent sense of ownership from the local community, and a sense of exclusion from the one of the few substantial open spaces on their doorsteps.

Geographical and ecological contexts

The Lee – or Lea – Valley is one of the few byways for migrating, wintering and breeding birds in the Greater London area, and as such acts as a ‘funnel’, refueling site and safe haven for hundreds of thousands of birds.

The Valley, while heavily urbanised and industrialised in its lower regions, consists of an almost unbroken chain of greenspaces, including woodland, marsh, wetland and reservoirs from its source well north of the city to the Thames.

Within an urban context, much of the valley’s wildlife and amenity value has been conserved not only by the protection of isolated sites, but also by the construction of reservoirs along its course, forming an artificial corridor where previously the River Lee and its array of natural and semi-natural habitats dominated.

This corridor remains open for a range of wild animals and plants which would otherwise struggle to penetrate or thrive within such a landscape.

As a consequence, the opportunities for local communities to access and enjoy such special areas still exist, an increasingly rare state of affairs in the capital.

In this context, important sites to the north consist mainly of large operational reservoirs (including King George V, Banbury and William Girling – the ‘Chingford group’).

These, while of vital importance to migrating and wintering wildfowl and other waterbirds, offer limited biodiversity value beyond this, and few opportunities for a more extensive variety of wildlife to develop populations or maintain footholds without more significant changes to the way they are managed.

Other areas of greenspace and important habitats along this stretch of the Lee Valley exist (such as Tottenham Marsh), but such sites are small, isolated and often require significant enhancement.

To the south, the Reservoirs adjoin Walthamstow Marshes SSSI, which is the only remaining pocket of traditional grazing marsh in the valley.

Further south, a cluster of sites south of the Lea Bridge Road constitute the end of the valley from a wildlife perspective, although there may be opportunities through the eventual completion of the Olympic Park post-transformation (after 2014).

The Reservoirs’ geographical position is almost unique. Such an important site – surrounded by heavily urbanised areas to the east and west, and interconnecting sites of high wildlife and biodiversity value to the north and south – contributes significantly to its potential as nature reserve which connects wildlife, landscape and people, and becomes a treasured asset for the communities of Tottenham, Clapton, Walthamstow, Higham Hill and beyond.

Image of gadwall and shoveler flying over Walthamstow Wetlands by Greg Morgan