So, using the FCC search page I linked to above, I put in the following:
Name = King
City = Hanford (County Seat)
Frequency = 450 - 470
26 Entries came up. Not all of them are the licenses for the Sheriffs Office, but a few are. Some are for their dispatch center, some are probably for public works. What matters is it'll give you an idea of what the county is licensed for. It's not unheard of for a county to use a public works channel as a back up for law enforcement. It's not unheard of to use a frequency intended for something entirely different as a secondary channel. Since the licenses belong to the county, they can do what they want as long as the license allows it.
So, could be the only have 4 channels and they left one out of the count for reasons unknown.
Could be that it's one of these below, low power, simplex and you'll never hear it unless you are close to them when they are transmitting.
Anyway, here's what came up:
460.075 KNAK370 FB2
460.125 KNAK370 FB2
460.500 WNDS201 FB2
460.550 KNAK370 FB2
453.0625 (SWAT/CERT) WPPV271, 2 watts MO only
458.0625 (SWAT/CERT) WPPV271, 2 watts MO only
453.1125 (SWAT/CERT) WPPV271, 2 watts MO only
458.1125 (SWAT/CERT) WPPV271, 2 watts MO only
453.3125 WQVH866 MO only
458.3125 WQVH866 MO only
462.950 WYZ262 FB2
463.000 WYZ262 FB2
463.025 WYZ262 FB2
463.050 WYZ262 FB2
463.075 WYZ262 FB2
463.100 WYZ262 FB2
463.125 WYZ262 FB2
463.150 WYZ262 FB2
463.175 WYZ262 FB2