Stupid boat situation

[Choparno]

No reads; UTG has just sat down and posted which you would think doesn't make him too bright, although you see this a lot on iPoker.

On the river it looks like I am getting valuetowned. I couldn't imagine that he would be trying to bluff me off a split, but I have no idea really. Call here? Bet/call river instead so it's easier?

3/6 NL, 6 players

Stacks:
UTG $600
MP $167.85
CO $89.30
BTN $575.10
SB $18.00
Hero (BB) $600

Preflop: Here is BB with K[img]/images/graemlins/diamond.gif[/img] 9[img]/images/graemlins/heart.gif[/img]
UTG checks, 3 folds, SB calls, Hero checks.

Flop ($24): 9[img]/images/graemlins/club.gif[/img] 2[img]/images/graemlins/diamond.gif[/img] 5[img]/images/graemlins/heart.gif[/img]
SB bets all-in $12, Hero raises to $36, UTG calls $36

Turn ($108): 5[img]/images/graemlins/club.gif[/img]
Hero bets $70, UTG calls $70

River ($248): 5[img]/images/graemlins/diamond.gif[/img]
Hero checks, UTG bets all in $488, Hero?