The bird was still present today morning.
BTW, yesterday I wrongly visited pond #20 in the morning from the boardwalk side and there was a group of tufted ducks as well. Among them, there was one that I think it is a female greater scaup, with a slightly bigger body with a round head, and more importantly the streaked back which was quite different from other female tufted ducks. But my equipment was too poor to catch a record shot since it was really too far away.
I hope other birders may take a look at it if you're interested. Thanks.