Aqueduct buffs may find two reports of interest. One is the excellent final report of a Columbia University graduate preservation studio, held in the spring of 2011, during which the Friends, among many others, provided assistance. The title is The Croton Waterworks: A Guide to the Preservation and Interpretation of Historic Infrastructure. To view this 291-page illustrated report, go to
http://www.arch.columbia.edu/files/gsapp/imceshared/Croton_Book.pdf.