well! i went out just now and guess who was bobbing in the water peering at me! and i've found it's little hidey-hole: it's beneath a ledge of flat rocks. i talked to it; it came over; i gave it some reptomin (much of which was stolen by the fish).
there's rock piled high along the pond's sides, and a wooden fence on all sides of the lot (except the back-most part, where there's chain-link). it's a pretty good-sized lot; it's not like a "postage-stamp" yard or anything. i'm going to sprinkle some sand on the rock i'd intended for basking to see if it's being used.
thanks, everyone.
