For a good starting point go to this site...
http://www.dec.ny.gov/outdoor/7749.html
On the left-hand menu you'll see 'Public Fishing Rights Maps'. You can click that and then click on the region you're interested in.
Also back on the first page, click on 'Region 3' on the blue state map and it'll take you to a page listing all the public ponds/lakes by county for that DEC region.
