Date Range Information for Metropolitan...

This guide provides a chart that shows the number of sewerage plans prepared during each decade across the 20th Century and provides advice on how to establish the approximate date for undated plans.

Source

This data file or API can be downloaded from:

https://catalogue.data.wa.gov.au/dataset/e773bb79-85f8-4c4d-b932-34599fddc8e0/resource/552e82eb-060a-4f63-8cca-c5a4264256eb/download/date-range-information-for-metropolitan-sewerage-scheme-plans.pdf