Managing Wanstead Park

Wanstead Park was purchased as part of Epping Forest in 1880 and has subsequently been listed as a Grade II* Registered Park & Garden; Site of Metropolitan Importance for Nature Conservation (SINC); Archaeological Protection Zone (APZ) Groundwater Protection Zone (GPZ) and forms the majority of the Wanstead Park Conservation Area.

There are currently some profound challenges in Wanstead Park due to the Large Raised Reservoirs being designated as ‘High-Risk’ in 2018, the Park and The Grotto having been placed on the Heritage at Risk Register (HARR) in 2009 and 2018 respectively and the long standing issues experienced with the water supply to the 300-year-old lake cascade system exacerbated by drier summers. This page outlines the background to these, and how we are currently managing those challenges. 

The Historic Cascade

Wanstead Park’s 300-year-old cascade lake system, which was originally constructed circa 1715, has had a long history of low water levels.

The City of London Corporation purchased what remained of Wanstead Park in 1880 to prevent further loss of the parkland landscape to development. At its greatest extent (circa 1800) there were nine lakes in the lake cascade system. Of these The Great Lake, The Reservoir, The Lake Pond, and the Square Pond have all ceased to exist. There have been significant changes to the size of Heronry Pond and the interaction of the Ornamental Water and the River Roding. At one time the River Roding was linked to the Ornamental Waters and flowed through the lake.

Today five lakes remain. They run in a semi-circle in an anticlockwise direction. The Basin, which is the head of the cascade in the ownership of Wanstead Golf Club, the next four lakes running down the cascade are Shoulder of Mutton, Heronry, Perch Pond and the Ornamental Waters (which is in the flood plain of the River Roding) are all under the City of London Corporation ownership.

The areas surrounding the Park have changed hugely over the centuries. The park catchment for water run off to feed the lake cascade system at one time extended as far Eagle Pond. This water ran through the ‘River Holt’, a ditch created by Adam Holt the gardener to the Earl Tylney. To the east and south of the park, the Lake House Estate and Albersbrook Estate where also once part of the originally parkland. These developments reduced the catchment area further.

Works were undertaken in the 1900s to reline the Heronry Pond and the result was much the same as we see it today. In the second world war the northern edge of the Heronry Pond was hit by several high explosive bombs. Then, in 1944, a V1 flying bomb landed right in the middle, creating a large crater. Repairs were carried out but were not successful in stemming leakage. Further attempts at repair were made in the 1950s but unfortunately we still have issues with leaks.

Originally, the Lord of the Manor was able to dam the River Roding to direct water into the Ornamental Water. Later, the City of London Corporation, while not able to dam the river, was able to pump from the Roding. This practice happened until 2000. In 2001 a borehole was sunk to pump water from the aquifer into Heronry and Perch Ponds – which continues to this day under licence from the Environment Agency.

How we currently manage water levels

The water levels in the lakes are maintained through pumping water from the borehole. The pump is operating at maximum capacity and works for two periods of eight hours with an eight hour aquifer recharge period.

Borehole water can be pumped directly into the heronry pond where this can be seen exiting a pipe near to the tea hut. Borehole water is also pumped into the Perch pond where it enters the pond below the surface so cannot be seen.

Once the Perch pond is full then the water overflows and goes into the Ornamental Water via a small stream through the Dell.

In the winter months we seek to get as much water as we can into the Ornamental Waters, however, in the summer months to keep water levels in the Heronry pond sufficiently high we need to pump more frequently into the Heronry pond. This means that water levels in the Ornamental water do get lower and the stream through the Dell can stop flowing for a while.

How we are making improvements to managing water levels

The City of London have taken a number of steps to address the low water including commissioning a detailed Parkland Plan and Hydrological Survey. In 2019, a 330m ditch starting near Blake Hall Road was cleared to enable water to move more freely helping it reach the lake system rather than be absorbed into the land. A Sustainable Urban Drainage scheme from Blake Hall Road was also investigated, however the assessment was that all that could be achieved in this area was already taking place. 

A waterscape ‘Adaptive Pathway’

A feasibility study undertaken by McCoy Consulting in March 2023 has mapped a series of 12 interventions that can be addressed incrementally and work continues to deliver these interventions. Named the ‘Wanstead Park Waterscape Adaptive Pathway’ the study addresses how to improve the resilience of Wanstead Park to water stress with an aim of maintaining lake levels and reducing dependence on the aquifer supply, which in turn benefits biodiversity and will help the landscape to sequester carbon.

Actions from this study currently being addressed are reed bed creation in Perch and Heronry Ponds. Initially intended to clear the ‘Lost Spur’ area of Heronry Pond, due to environmental constraints the project is now focussing on floating reedbeds which will improve water quality particularly in areas where urban drainage enters the ponds. This project is being led in partnership with Thames 21 who have provided £80,000 towards the project via funds from Britvic.

The next projects to be addressed will be drainage schemes from the neighbouring golf course to improve flow into Ornamental as well as Shoulder of Mutton.

Why floating reed beds?

Floating reedbeds offer several environmental benefits, particularly in urban or natural water bodies like Wanstead Park, where they can serve as a natural filtration system. These innovative structures consist of plants such as reeds or sedges, which are anchored to floating platforms on the surface of water bodies. Their ability to filter pollutants from outfalls is invaluable for improving water quality in such ecosystems.

One of the main advantages of floating reedbeds is their capacity to absorb and filter out harmful substances, including nutrients like nitrogen and phosphorus, as well as heavy metals and other contaminants. The roots of the plants trap pollutants, preventing them from being dispersed further into the water.

Additionally, the plants can remove excess nutrients, which often contribute to algae blooms, thus helping to maintain a healthier aquatic environment.In the case of Wanstead Park, where storm inlets may carry pollutants into the lake cascade, floating reedbeds can act as a natural buffer. They improve water clarity, reduce the occurrence of unpleasant odours, and enhance biodiversity by providing habitats for birds, insects, and small aquatic creatures.

Another key benefit is their ability to adapt to fluctuating water levels, a common characteristic of the lakes in Wanstead Park. This flexibility allows floating reedbeds to remain effective in diverse conditions. Additionally, they are low-maintenance, providing a sustainable and cost-effective solution for managing water quality without the need for complex or expensive infrastructure.

The installation of floating reedbeds in Wanstead Park’s water management will enhance the quality of the park’s water, promote biodiversity, and offer a long-term solution to the challenges posed by water pollution.

Abstraction from River Roding and pumping into Ornamental Water

An abstraction licence is in place to pump 236,520 m3 of potable aquifer water each year to 2028. Currently this is pumped directly into the Heronry Pond and from there down through the cascade. This is not a long-term sustainable operation due to ground water shortage and the aim is to reduce or cease this in future. Therefore, the reinstatement and extension of an ‘up cascade’ scheme is being developed. Consultants are currently working on detailed specification and tendering for the new pumps/pump house and an application has been submitted to the Environment Agency for a new licence to pump water from the River Roding.

The proposed new pump house will include filters and pumps which prevent fish (including eels and elvers) being drawn into and harmed by the pumps. The filtration requirements involve quite sizeable mesh "screening" around the suction inlet with a built-in rotary cleaning device and a built-in back wash pump.

Water from the Roding will only be pumped while it is in spate during the winter. This is when there will be sufficient water not to harm the habitat within the Roding but also the water quality will be better. The water will fill Ornamental and then be pumped ‘up’ the cascade using a new pump from Ornamental in to Perch Pond. This project is being entirely funded by the City of London. Any ‘excess’ water will naturally flow back in to the Roding.

The Large Raised Reservoir

In 2018, the Environment Agency confirmed the water bodies within the Park as “High Risk”, large raised reservoirs. The risk is about potential for damage to surrounding properties due to flooding.
As a result, The City of London Corporation commissioned a one-year study by consulting engineers to ensure that the dams operate safely during major flood events. The City is now investing £1.15 million to reinforce dams in the Wanstead Park ponds and implement flood prevention measures, this includes grass management to Shoulder of Mutton dam, dam strengthening works to Heronry and Perch and dam re-enforcement works to Ornamental Water (north wall and canal wall). A new pump will be installed to pump from Ornamental Water in to the Perch Pond.

Preparatory works and tender processes are underway with works anticipated to take place in the autumn of 2025.

Water levels and wildlife

Staff and volunteers monitor the wildlife of the lakes. However, if you have any concern please contact the Epping Forest Team.

If you see animals in distress, you can find out what to do on the RSPCA's website.

Other management projects in Wanstead Park

Lots of improvement projects are currently taking place in Wanstead Park, including;

• A major project to remove the Grotto from the Heritage at Risk Register.
• A new conservation management plan at The Temple was recently completed to help us to take the best care of this Grade 11 listed building.
• A new play area to the rear of the Temple has been installed with support from the Aldersbrook Families Association and Friends of Wanstead Parklands. Further improvements to this area have been planned and will be implemented once the necessary permissions have been obtained.
• A new programme board has been set up to ensure that all the projects taking place are being managed to complement each other and consider any constraints.
• A new group is meeting from the autumn to start discussions around a refreshed master plan for Wanstead Park to take account of the many projects that have already been incrementally implemented but also to plan funding and future projects that will improve the visitor offer and interpretation of this exceptional parkland.