My views are based on a couple of maps. So that others can judge I've put them on flikr at:
These are the notes that I sent to Pat explaining the maps:
I believe the fact that the Commission of Sewers was considering using the spring to supply their reservoir suggests that it was fairly vigorous. We cannot, of course, be certain that today the stream and lake are supplied by a spring higher up the hill, but I believe they are.The Metropolitan Commission of Sewers map was produced in 1849 when they were planning a sewerage system for Sydenham. The plans were later modified (the “proposed reservoir” was built on the other side of Sydenham Hill, for example), but it clearly shows two streams flowing down the hill, and merging just beyond Taylors Lane. The stream flowing from the site of the proposed reservoir is the one that I was referring to. By comparing it with the 1916 map it is on the same alignment as the stream and lake in today’s park. The “Stone” by the “g” of Longton Grove (a Bridge House Estates stone, by the way) is on the top right corner of the proposed reservoir and the piece of woodland is where the recently demolished houses were built.
The following quote, from the leaflet produced for the opening ceremony, makes it clear that “existing watercourses” (note the plural) were incorporated into the landscaping:
“The land as acquired was very undulating in form, being practically a basin formed by the conjunction of two separate valleys and having a general slope from west to east. Advantage has been taken of the
natural undulations and the existing watercourses [note the plural]”
For Falkor I've also put up part of the Land Use map showing the streams on the common