[Kvacke]

He is only raising 10% of his hands and are opening from UTG. That means that he will have quite a good hand. AT-AK have u beat, KJ-KQ have u beat, He does not raise QJ U are only beating pocket 88-TT.
so c/c with your good flushouts seems fine. If he bet u fold when he bets the river UI. Improved u bet out.
Intressting is if he checks the turn, u miss, and he bets the river when u check again. Do we call here? does he have a lower pocketpair enough that he tries to bluff?