Intranet site for Organization with multiple (77) chapters Need edit help

Does anybody know a plug in or other work around that would allow me to designate ONE editor for each of the 77 pages.. so that they would be able to update ONLY their page and not any other page in the site.

Seems that if I use the User function within WordPress and designate a person an editor, they can do more than just their one site page and we do not want them to have access to more than their one chapter page.. ie Birmingham, AL only can update their page
Palm Desert, CA only can update their page

Your help is sooooo appreciated as I will guarantee you that I do not want to have to keep the whole site updated plus the chapter sites.

Thanks