It is usually on the Sunday of President's Day Weekend, with Presidents Day being the 3rd Monday in Feb.
Here is Contact info for Alton Parks and Rec. You can contact them for the information:
<TABLE border=0 cellSpacing=2 width="100%"><TBODY><TR><TD vAlign=top align=right>Contact Info:</TD><TD vAlign=top>328 Main Street- A.V.A.S. Public Park
P.O. Box 659
Alton, NH 03809
(603) 875-0109
Fax (603) 875-0242
<SCRIPT language=JavaScript type=text/javascript> print_mail_to_link('parksrec','') </SCRIPT>parksrec@alton.nh.gov (parksrec@alton.nh.gov)
</TD></TR></TBODY></TABLE>
Hope that helps you. Also, welcome to the Forum.