Snohomish County’s Department of Emergency Management lists the Auxiliary Communications Service as one of its volunteer organizations. The City of Marysville notes that county ACS operators staffed the EOC radio room in Everett and a command vehicle in Darrington for the length of the 2014 Oso landslide response.
City teams in the county, such as Marysville ACS, train alongside it. You need an amateur radio license for most roles.
Volunteers serve through the program, not on their own: register as an emergency worker through the sponsoring agency before you help in an emergency.