How the project started
Historic Watercourses in the Redington Frognal Area
Meetings from 2015 (which focussed on the undiscovered headwaters of London rivers, especially those around Hampstead Heath) lead to the Neighbourhood Forum considering a project to map unidentified underground rivers, to form part of the evidence base for a Neighbourhood Plan policy on underground development. Arup was commissioned to research the hydrogeology of the Redington Frognal area and their Mapping Report was completed in April 2016, shown below. There is more on Historic Watercourses and flooding here.
Sub Surface Water Features in the Redington Frognal Area
Source: Arup / RedFrog
https://www.redfrogforum.org/underground-rivers/
The Arup map of RedFrog underground rivers indicates the presence of many historic rivers, such as the Westbourne, East Westbourne, Cannon, Boundary Stream, unnamed rivers, springs, wells and ponds. Of these, one clean stretch of the underground Westbourne is known to remain: clean water runs between Branch Hill and Redington Gardens, where the stream can be heard.
Ponds in the Redington Frognal Area
The Arup map also records that at least 20 ponds had formerly existed in the area. These have since been covered over and, as elsewhere in the country, this has contributed to the catastrophic decline in biodiversity:
https://www.wildlifetrusts.org/habitats/freshwater/ponds
https://www.countrylife.co.uk/news/lack-of-ponds-a-national-crisis-team-works-to-restore-watery-habitats-across-uk-203725
With this in mind, Redington Frognal Association applied for grant funding from both the Mayor London’s Greener City Fund and from the City Bridge Trust Enjoying Green Spaces Fund, with the aim of reinstating Branch Hill Pond. The applications were supported by Cllr. Spinella, Heath and Hampstead Society and Hampstead Neighbourhood Forum.
Now find out how the project is developing here.
Award of Grant Funding to Redington Frognal Association
Redington Frognal Association applied for grant funding from both the Mayor London’s Greener City Fund and from the City Bridge Trust Enjoying Green Spaces Fund, with the aim of reinstating Branch Hill Pond. The applications were supported by Cllr. Spinella, Heath and Hampstead Society and Hampstead Neighbourhood Forum. Both applications were successful and, in 2018, Redington Frognal Association was awarded grant awards totalling £25,000.
Redington Frognal Association has been working together with the Superintendent of Hampstead Heath, and the funding has been spent on exploratory hydrological scoping work and design. This has been undertaken under the direction of the City of London’s team of Ecologists. Scoping work included the excavation of boreholes to analyse soil samples at thirteen different sites. The soil samples yielded were then laboratory tested for geotechnical and geo-environmental properties.
Area of former pond and window sampling rig, 25 June 2020
Ground investigation and soil sampling at Branch Hill
Wet ground at Branch Hill
Excavation and reinstatement of the former pond will attenuate the water that flows into the culvert beneath Branch Hill, thereby reducing any risk of surface water flooding further downstream. The reinstated pond will be a natural wildlife pond, which is expected to attract frogs and dragonflies. The pond will be fenced, inaccessible and unobtrusive. It will be important not to introduce fish, so as not to upset the delicate ecological balance.
The pond will provide a significant benefit for biodiversity and will look much like the No. 1 Pond in the Seven Sisters chain on the Heath Extension.
Planning Application for Reinstated Pond at Branch Hill
The pond received planning consent (2021/4816/P) on 22 December 2021, with excavation following in August 2022. Work on the pond is due to be completed in early 2023.
Presentations given at the press night launch of the reinstatement of Branch Hill Pond, held at Burgh House on 8 February 2022.
Jonathan Meares, Conservation and Trees Manager, Hampstead Heath
The presentation by Jonathan Meares, the Conservation and Trees Manager for Hampstead Heath Natural Environment at the City of London Corporation, documents the planned development of Branch Hill Pond. It is available here:
Jonathan Meares – Branch Hill Pond project 070222
Dr. Adam Broadhead, Senior Scientist, Water Environment and Flood
Risk, Arup
The presentation by Dr Adam Broadhead about the daylighting of lost rivers is available here on the Underground Rivers page of the site.
Following completion of exploratory works, Branch Hill Pond was excavated on 11 August 2022. It became filled with rainwater and groundwater on 17 August 2022 and has remain filled ever since.
Newly excavated pond on 18 August 2022, following previous day’s thunderstorm
Credit: Redington Frognal Association
Project updates 2023
During 2023, water levels were being closely observed including over the dry summer months. The monitoring suggests that the pond is fed from groundwater, which is consistent with the pond as the source of the River Westbourne, as well as from rainwater.
Monitoring also found that it was used as a dog wash pond. Neocotinoids, used as parasite treatments and preventatives, are powerful killers not only of bees but also of insect larvae, such as those of mayfly and dragonfly which are important food for birds and bats, among other species.
To preserve the pond for wildlife, fencing was therefore erected in Autumn 2023.
The survival of wildlife over winter is supported by a deeper area of approximately 1 metre by 2 metres, which was excavated on 19 September 2023. This is to aid water retention and provide space for species to hibernate.
Pond incorporating deeper refuge, excavated 19 September 2023
Credit: Richard Payne, Nature Conservation Officer, Hampstead Heath
Pond with raised water level and fencing on 3 November 2023
Credit: Richard Payne, Nature Conservation Officer, Hampstead Heath
Bat and bird boxes were put into the trees over the summer. A small deeper area was excavated in September, the blocked culvert beneath Branch Hill was cleared and construction of an extended brick overflow was completed. This has raised the height of the pond to become level with the surrounding grass to provide greater drought resilience, and it will almost double the surface area of the pond, making it appear much larger.
In November the surrounding bank and hillside were planted with over one thousand wildflower plugs and three thousand spring and summer flowing bulbs. Planting was undertaken during six Heath Hands volunteer sessions, contributing approximately one hundred and sixty hours of individual volunteer time to this project.
The results will be visible in spring 2024.
Potential planting for the surrounding hillside
