Complex sentence: Arcata/Eureka Airport (Arcata Airport) is a county owned, public airport in Humboldt County, California, located north of Arcata and north of Eureka, in McKinleyville, California.
Split into simpler sentences: Arcata/Eureka Airport (Arcata Airport) is in Humboldt County, California, which owns it. It is north of Arcata and north of Eureka, in McKinleyville, California.