The name comes from the Irish immigrants who settled in the area in the 19th century.1
In the 20th century, several chromium and mercury mines were in operation in the Irish Hills, and tailing piles, process ponds, and mine shafts still exist in the area.
For mountain biking, trails range from beginner-friendly routes in the lower elevations, such as the King trail, to more technical trails in the upper elevations such as the rocky western side of the Maripossa trail descending to Perfumo Canyon road, and Miner's trail which descends steeply to an abandoned chromium mine. Recently trails have been completed by Central Coast Concerned Mountain Bikers (CCCMB) connecting Irish Hills to the Johnson Ranch open space.
Entrances to Irish Hills can be found on Madonna Road and just off of Perfumo Canyon Road.
There is also a small dirt jump area which can be accessed either from the Madonna entrance or the Costco parking lot.
- Mark P. Hall-Patton Memories of the land: placenames of San Luis Obispo County EZ Nature Books (1994) p. 72