IR2 is a good investigator. He first evaluated the edges of the Irvine Ranch from the first clue. Then he studied the the towns near by the perimeter edges that had population and demand for water consumption during the time of the WPA era after the depression (1931-1939).
Knowledge is his strength and knowing the development of OC he quickly employed the process of elimination narrowing his focus on the the few historic towns with sizable population and demand for water. He also knew the clue as population expanded such a limited retention was replaced by larger cavities to sustain the growing population since the 1940s. By checking the aerial and the map he posted he narrowed in his search and found a specific public project and a document link that has 92 pages that illustrated this particular landmark and facets.
I have very little respect for realtors but IR2 and his understanding of our environment, history, research, market, and people. He has earned a very high place in my book. He is a testament of someone who truly loves Irvine and his action and knowledge synchronize with his words.