Commissioner reports are great but remember they are the parks’ slant on things.
Robert Caro’s THE POWER BROKER does a number on Moses. Text includes input by various groups re the introduction of highways. The New York Times has articles by Moses which give his point of view and also editorial pieces opposing highway construction. If you can get a library copy of <span style=”text-decoration: underline;”>Urban Ornithology</span> by Paul Buckley, much of park history is given including how the land was divided/upset. The book is pricey and is for serious birders but has comment, references and maps that should be helpful to you.
There’s a lot on the web about the Filtration Plant Van Cortlandt Park – a search will bring you to a voluminous document.
Good luck!