Walthamstow Wetlands: Ornithological Survey, Design Inputs & HRA Support


The Walthamstow Wetland Project is a Heritage Lottery Funded (HLF) project that has lead to the provision of the largest urban wetland nature reserve in Europe.  The reserve provides opportunities for local communities and schools to have better access to nature and to a wide range of leisure activities, whilst also supporting physical regeneration plans in surrounding areas.

The project was developed by the Walthamstow Wetlands Partnership, led by the London Borough of Waltham Forest Council alongside site owners Thames Water and a series of other partners including London Wildlife Trust, Natural England, the Environment Agency and adjacent local authorities.  It achieved planning permission in June 2014, and was subsequently fully opened in October 2017.

Walthamstow Reservoirs is a complex of ten waterbodies forming part of the Lee Valley Special Protection Area (SPA). The Lee Valley was classified as an SPA (in 2000) on the basis of its populations of wintering bittern, gadwall and shoveler which are considered to be of European importance.   The reservoirs have also been notified a Site of Special Scientific Interest (SSSI) in their own right due to the presence of a nationally important heronry, and large numbers of breeding, moulting and wintering wildfowl.

BSG Ecology’s Role In The Project

BSG Ecology was appointed by Thames Water in 2011 to lead the completion of technical ornithological studies at Walthamstow.  Under the Conservation of Habitats and Species Regulations 2010 (as amended), the proposed access strategy needed to incorporate mitigation to demonstrate that a significant effect on the integrity of the SPA could be avoided if the project was to be granted planning permission.  In order to gather the information to support this assessment, BSG Ecology completed a detailed desk study of existing ornithological information and designed a bespoke survey programme to enable accurate mapping of bird numbers and distribution around the site.

The initial survey involved mapping all wintering waterfowl species using a gridded system extending across the reservoir complex.  Surveys were undertaken on a twice monthly basis during the winter periods of 2010/11 and 2011/12.  Care was taken to vary the timing of each visit and the order in which reservoirs were visited, and to ensure that data were collected in a representative range of weather conditions.  In addition, detailed observations were made on the reactions of individual species and mixed flocks of birds to baseline levels of disturbance, particularly in respect of: maintenance works; the presence of fishermen; and other intermittent disturbance events (such as trains on a line passing between two of the reservoirs and overflying helicopters).

Following the wintering bird survey contract, BSG Ecology was appointed by Waltham Forest Council to undertake an extended Phase 1 habitat survey, an invasive plants survey, breeding and post-breeding duck survey and heronry counts to gather further information on the SSSI features of the site.  This provided a comprehensive baseline to support the detailed design process, which was led by Kinnear Landscape Architects.

The data generated by the survey work were imported into GIS, allowing ‘heat maps’ for all key bird species to be generated on both a single visit and seasonal basis.  The maps demonstrated clear patterns of seasonal occurrence and distribution of key species within the waterbody complex.

Due to our long-standing involvement with the project, knowledge of the site and understanding of the wildlife conservation sensitivities, we were retained on the consultant team as the project moved into the detailed design and assessment phases. Subsequently we co-ordinated monitoring work to determine whether the design of the site fully mitigated impacts on waterfowl.


The data collected were summarised in a series of detailed technical reports.  These were subsequently appended to a report to inform an Appropriate Assessment (AA) for the site (produced by BSG Ecology).  In the lead up to the delivery of the AA report, there was considerable liaison with Natural England in order to discuss and agree a way forward on outstanding concerns.  A separate report on potential effects on SSSI features was also completed.

The reports provided the basis for Natural England to agree that no significant effects were likely on either SPA or SSSI features, based on design and operational phase measures such seasonal access restrictions to sensitive areas, and active visitor management through wardening, hide provision, signage and screen planting.  In addition, a range of practical and deliverable habitat creation measures were offered to provide opportunities to enhance the value of the reservoirs to key bird species.

The development was consented by Waltham Forest Borough Council, subject to planning conditions, in June 2014.  One of the conditions related to residual uncertainty with regard to the effects of recreational pressure on birds.  While the baseline work strongly suggested that the mitigation proposed was likely to be fully effective, a protocol was needed to provide evidence of this.  This required agreement with Natural England, year-round survey and annual reporting to the Wetlands Partnership Board.


BSG subsequently completed monitoring work during the construction and phased opening of the Wetlands. This established that while bird numbers fluctuated between years (as they had done during the baseline data collection period), their distribution was consistent, and the mitigation incorporated into the design of the site effective. The results were reported back to a board of nature conservation stakeholders on an annual basis for three years, following which the longer term monitoring of waterbirds was passed to London Wildlife Trust.

Rose Jaijee, the Walthamstow Wetlands Coordinator at Waltham Forest Council stated:

“BSG Ecology provided technical ecological support to the Walthamstow Wetlands project for over seven years. Over this time the project developed from a concept to become Europe’s largest urban wetland nature reserve.

 The Wetlands form part of the Lee Valley SPA, and a key challenge in achieving planning consent was to ensure that the scheme design was adapted and additional controls identified to effectively mitigate impacts on the European Site. BSG were appointed at the concept stage and subsequently as an important member of an excellent multidisciplinary project team. BSG provided the technical vision to help guide the project team through the  process of developing a scheme that effectively balanced the objectives of access to nature and protection of wildlife (through survey design, effective stakeholder and project team liaison, advice on mitigation and enhancement measures and through monitoring work).”



Thames Water

Key Services

London, Public Sector