Suppose a Kohain for some reoson forgot to wash his hands or was unable to, can he still do Birchas Kohanim?
1 Answer
If he washed his hands that morning and knows definitely that he hasn't touched any unclean parts of his body, then he can get away without another washing, if there is indeed no water available (Mishnah Berurah 128:20 citing Rambam).
Otherwise, though, he does need to wash, and can't do birkas kohanim otherwise (R' Yehoshua ben Levi in Sotah 39a; Shulchan Aruch Harav 128:9).