Update, 1 p.m.: Common mistake, as Mark notes below: Not Eureka, Yreka. Despite doing two other jobs in the Humboldt County seat, the Millcon Group still got Eureka mixed up with our country cousin over in Siskiyou County. So, for now, the mystery continues.
Resourceful blog commenter "James" has tracked down the evidence. The above image comes from a list of current projects for a Texas-based air conditioning/insulation company called the Millcon Group, which has been subcontracted by the general contractor, R&O Construction of Ogden, Utah. (The Millcon site also lists a completed project for St. Joseph Hospital and an awarded contract for the new Eureka Safeway on Harris St.)
Expect more info in next week's Journal.