Yesterday I flew back and forth between Vegas and San Jose a couple of times and noticed some dirt strips. I'm hoping someone will know about them and if they are legal to use.
1.) This strip is located on the east foothills of the mountains, approximately 15 miles northwest of Bishop. It is situated north to south, on a high plateau. Southwest of Red Slate Mt.

2.)Another north south dirt srtip on the El Nido 085 at 46-50 dme. It is on the western foothills, west of most of the little lakes. Between Huntington and Shaver lake.

3.) I guess all these are north south strips, anyway the last one is 20 miles east, northeast of Gilroy in the mountains. It is north of the highway. I would say it is almost at the top of the hill. look near Cathe intersection.
All of these didn't look like they got much use, but from my lofty vantage point , they all looked usable. I'm only estimating the distances. Believe it or not 737's don't have a "mark" function so I have to guess on these positions.
For the record, I just happened to notice these strips as I was looking for traffic. I certainly wouldn't be looking for places to land 5PL at work!

The first strip you mentioned used to be Coyote Flats airfield.

'It was built in 1968 by the Army High Altitude Test Center as a facility to test the high altitude performance of helicopters & light airplanes. It was also used in a similar capacity by the Marine Corps Mountain Warfare School in Bridgeport, CA.'

It was the highest paved airfield in the lower forty-eight until the forest service tore it up and returned it to it's 'natural state'. Used to drive by that field for many years on my way up the lakes above it to trout fish. People still land on occasionally, but don't do it when the ranger is around.

Abandoned and Little Known Airports - California

Airstrip Junkies