If he died in Chili NY (instead of Little Falls) a drowning would be newsworthy. It should have been in the papers. If you do not find anything in the web site www.fultonhistory.com
, then you can order the Rochester papers from the NY state library for a few dollars on inter library loan. Since you have the death certificate, you should have the date. As well, while they are not online, the county medical examiner or police might have records of such an occurrence.