The builder of this wall and the time of its construction remain a mystery
This concrete wall runs along a section of the Wainuiomata River in Reservoir Valley. It is situated approximately 50 meters east from the Reservoir Road car park on the river’s northern bank. The wall’s foundation extends below the riverbed, and the land above the wall contains buried water pipes.
The wall was likely constructed to prevent erosion of the riverbank, perhaps during periods of high water flow. Although the bank lies on a straight stretch of the river, a solid rock formation on the opposite side deflects the flow towards the softer, more vulnerable bank with the road above. Given this, it’s possible that the construction occurred simultaneously with the installation of the underground pipes.
To determine the age of the wall, one could test the concrete and aggregate to see if it matches either Lower Dam or Morton Dam. If it matched the Lower Dam, then it is plausible, that the wall was built following a severe three-week rainstorm in 1883, which caused the river to swell and flood, resulting in a 9-meter-wide breach in the dam. This breach could have washed away part of the bank where the wall now stands. Due to the scale of destruction on the dam, repairing the river bank might not have received much or any media attention.
The Evening Post did report a landslip on 25 Oct 1883 just after the time of the dam breach, which may or may not be related. This landslip prevented visitors from using the old railway to access the dam in order to see the breach for themselves. The visitors were forced to walk the final 20 minutes to Lower Dam which is approximately where the concrete wall is in relation to the dam. Another possible date for the wall could be: 19 October 1904. The Evening Post reported a flood that was the worst since 1895 causing numerous slips, thus 1895 could also be a contender.
These examples are speculative based on the similarity of concrete in the wall to that in the Lower Dam. However, if the concrete matched Morton Dam, it is possible then that the wall was built at the same time as the pipes adjacent to it were installed, which would date it around 1911.
Credits
Special thanks to Jeremy Foster for pointing out the location of the wall.
Special thanks to Carl Smith for providing a possible explanation on the timing and reasons behind the wall’s construction.
