Thanks for the reply Norman but I have all the repeater listings.
I am actually looking for ARES activities for the fire specifically. It could very well be that Mariposa County doesn't have an ARES organization. Otherwise, most local hams would be familiar with the specific repeater(s) used for an ARES activation in their county.
Seems odd that entire communities are evacuated and no ARES activation would occur.
These two ARRL articles should get you pointed in the right direction.
Go to QRZ, look up callsigns and either email these organization members OR look up their phone numbers. The "Maripos Area..." listing in the ARRL website has phone numbers/emails listed for one officer.
The Salvation Army also has a SATERN Ham Radio Network; there may be one in existence for Mariposa County.