I reviewed the last twelve months of generation history for all balancing areas in California using electricitymaps.com before making my statement, and while one balancing area has any coal generation capacity remaining (WAPA Desert Southwest with 204MW), there is no evidence it has been fired in the last twelve months [1]. This is a bit tricky, because of the balancing areas's service area [2] and it doesn't appear there is a coal generation in their service area [3]. I'll make a note to call their media number to get more detail about generation mix and review EIA's latest EIA-860M [4]. It may be Apache Station [5] near Tucson from a quick glance before I've had coffee, but they are owned by Arizona Electric Power Cooperative.

Appreciate you pointing this out!

[1] https://app.electricitymaps.com/map/zone/US-SW-WALC/12mo/mon... (hover over coal on the left nav)

[2] https://www.wapa.gov/about-wapa/regions/dsw/about/

[3] https://www.sierraclub.org/coal/coal-plant-map

[4] https://www.eia.gov/electricity/data/eia860m/

[5] https://www.gem.wiki/Apache_Generating_Station