My father worked at Mattawan when we were small. He worked in the section where the inmates were drug abusers. This was in the 1960's. They had a workshop there, he bought us a beautifull little table and 4 chairs, very well made and painted. I still have it. I know he didn't like working there because the inmates could sometimes get violent. I'm not sure of any other place to get info besides what is mentioned on the last posting except the History of Fishkill paperback. There are books about small towns in New York.
Good Luck