The River Effra’s original natural mouth lay at Walworth Marsh (in modern-day Southwark), where it emptied into the Thames. This area was a low-lying, waterlogged floodplain known as "Walasþorne" (Walworth Marsh), with the mouth serving as a small but functional interface between the land and Thames. It supported local agriculture, with nearby fields irrigated by the Effra’s flow, and was used by communities for access to the river, fishing, and transporting goods short distances.
Redirection (13th Century)
In the 1230s, the mouth was deliberately moved west by the Bishop of Winchester, Peter des Roches, who controlled land in Lambeth. The new location was near Vauxhall Bridge (then a simple river crossing), in an area later called Lambeth Marsh. This redirection was driven by practical needs: to supply water to Lambeth Palace’s estates and reduce flooding in Walworth Marsh, where the original mouth sat. The repositioned mouth became a landmark for locals, marked by a small jetty or sluice structure.
18th–19th Century Changes
By the 18th century, urban expansion and industrial waste had turned the Effra into a polluted open sewer. Heavy rainfall and poor drainage led to frequent floods in Lambeth Marsh (around the mouth), with the 1774 and 1848 floods being particularly severe, submerging streets and homes. In the 1850s, Sir Joseph Bazalgette integrated the lower Effra into London’s sewer system, culverting the final stretch to the mouth. The visible mouth was enclosed in an iron or brick structure, becoming part of the Thames Tideway’s infrastructure.
Modern Era
The mouth is now located close to Vauxhall Bridge in Lambeth, between St George's Wharf and the bridge’s southern abutment. A small, grated opening marks the spot—often obscured by the sculpture Science (part of the bridge’s decorative scheme) and adjacent river walls. While the Effra no longer flows openly as a river, its mouth is recognized as a historic point in London’s lost river network; plaques and local initiatives occasionally highlight it, such as a 2009 "Effra Discovery Trail" that included the site.
Finding the cache.
you should be at the Effra ilse information if so then let's get started.
51.(A)(B) N 51. ----- N
0.1268(C) W 0.1268- W
A=
heat wave +3000
B=
First find the year the ferry was replaced
by a bridge. take the 1st digit away from the last digit. You only need that one digit
(eg 1234 take 1 away from 4 = 3)
C=
how many million
Were allocated to improve
londons Polluted River?
THE COORDINATES MAY SEEM UNFAMILIAR, but when entered into either google maps or apple they will work as long as the decimal is as shown above.