The original water supply
When Regent’s Park was laid out from 1811 the lake was supplied by the Tyburn Brook.
The traditional source of the Tyburn is marked as Shepherds Well, on the corner of Fitzjohn’s Avenue and Akenside Road. The site is handsomely marked by a red-brick memorial and tablet.
The Tyburn crossed Avenue Road just beyond St. Peter’s Church (now Queensmead). Keeping close to the west side of Avenue Road it reached Acacia Road, at the corner of which it received a tributary from Belsize. It then flowed southwards by Townsend Road to the corner of Henry Street (now Allitsen Road) where it diverged diagonally to the corner of Charles (now Charlbert) Street with Park Road (now Prince Albert Road). Here it entered the park to supply the artificial waters of the lake.
After the Regent’s Canal was built, a small aqueduct carried the stream into the Park over what is now Charlbert Bridge. The extract from Cary’s Map of 1837 shows the route of the Tyburn at that time.
Drainage and wastewater
A new sewer drained from St John’s Wood into the public sewer in Baker Street North, passing under the Canal, as a condition imposed by the Eyre estate, which owned the land, on keeping the Regent’s Canal in open cut through this section.
The Tyburn continued its course, after diversion through the Park, passing from the park boundary at the upper end of Cornwall Terrace and crossing Upper Baker Street. At different periods the stream was altered in various parts of its course, and gradually covered in and converted into an underground sewer.
It was not long before the quality of the Tyburn Brook was unacceptable for supplying the lake and replaced by municipal water supply. The part-foul Tyburn river/sewer continues to be carried in a pipe through the Charlbert Street footbridge over the Regent’s Canal but is now diverted under the Outer Circle to the Baker Street area.
There are two overflows from the lake into the mains sewer system. One is in the middle of the lake. The other on the west side close to the edge is just past the exit to Kent Passage and enters the sewage system opposite the London Business School.
Problems created by WWII
The Cumberland Branch of the Regent’s Canal had been dammed and drained in 1838. It became a repository for bomb rubble from WWII. However, clearing bomb damaged sites required a far greater area, and rubble was spread across much of Regent’s Park and Primrose Hill. The extent of the areas filled, and of the rubble and shallow soil laid down, is apparent during droughts as may be seen from the oblique aerial photo.
The overall depth of rubble fill may be gauged, as shown in the photo, by walking along the southern perimeter of the Zoo. The informal path at Zoo level lies well over a metre below the asphalted footpath above, which is at the fill level, as are the sports areas alongside.
Topsoil was replaced to a depth of only about 6 to 12 inches (15-30 cm). This has created major difficulties in maintaining a level grass sward. Costly resurfacing with a sandy loam needs to be carried out on a regular basis to prevent compaction and ponding and facilitate drainage.
Irrigation is essential for sports pitches and is also needed after major events such as Taste and Frieze to help the newly sown grass or turves to reinstate the areas swiftly.
A legacy of WWII is an 18 inch steel main that runs N-S under the Broadwalk, believed to have been installed for firefighting. It drew water from the Cumberland Basin via a pumping station and leads to the southern boundary of the Park, from where it served the West End fire services.
It now forms part of the Thames Water mains supply system. Prone to rusting and leakage, it has suffered several bursts and needs careful monitoring. Thames Water’s pipes are generally in such poor condition that, if the Royal Parks need to use them, Thames Water reduces the pressure to minimize the risk of serious failure.
For many years mains water was used to supply the needs of the Park, but in the early 2000’s it was decided to sink a borehole.
The Royal Parks have an abstraction licence from the Environmental Authority for Regent’s Park boreholes. The abstraction licence was given for Borehole (BH) 1. BH 2 was sunk to create greater flexibility of supply, but the amount that may be abstracted from the chalk aquifer has not changed. The boreholes are not used for drinking water.
BH 1 was sunk just outside the Nature Study Centre just north of the two blue bridges that together form Hanover Bridge and the toilet block. It feeds a holding tank from where it is pumped for flushing toilets, irrigation and supplying the main lake, in that order of priority. It has an extensive pipe network extending to Chester Road, close to BH 2, although it operates quite independently.
Irrigated areas include sports pitches, the Winter Garden and Queen Mary’s Garden. There is also overhead irrigation/fire control for compost heaps.
Water enters the main lake via the cascade you can see from the Hanover Bridges looking into the Wildlife Centre, as seen in the photo. As well as the main lake the supply is piped to the kids’ boating lake and Queen Mary’s Garden lake.
BH 2 is half-way down the north-south path on Marylebone Green. It was sunk in 2018. It was drilled about 70 m to reach the chalk aquifer, and a further 30 m into the chalk.
It operates independently from BH 1 and supplies Avenue Gardens with irrigation via a valve, taps and control board. The artificial stream in the Wildlife Garden, which cascades into the lake (see photo), is supplied either from the lake by a recirculating pump or manually from BH 2 via a tap and pumps.
All the water bodies are topped up manually.
On 15 January 1867, 40 people died when the ice cover on the boating lake collapsed and over 200 people plunged into the lake. The lake was drained and reduced to four feet depth before being reopened to the public.
The need to keep the lake topped up in the summer months was apparent as early as the 1980s, to keep the lake as cool as possible, prevent blanket weed from covering the lake and avoid the risk of botulism.
The shallowness of the lake creates problems of temperature control. It also increases the threat of botulism. There are several discharge points into the lake from BH 1, arranged to keep water moving, cool water and prevent oxygen reduction.
Expansion of the reed beds is another part of the strategy for improving lake quality.
Strategy for the future
The Royal Parks (TRP) is concerned that climate change and drinking water priorities will lead to a reduced amount of abstraction from the chalk aquifer being permitted by the Environment Agency.
There are also concerns with the long-term supply of the chalk aquifer from the Chilterns.
TRP realise that they must use water frugally and are taking steps to automate and computerize the supply to make the most effective use of water.