Ok- I live close and was raised in this area. I've spent lots of time here. The road known as Ebbets Pass is HWY 4. It goes up through Murphys and Arnold, past Bear Vally ski resort and Lake Alpine. Ebbetts pass is beyond that, going up into the Sierras proper, ending up in Nevada.
Valley springs is actually much closer into the San Joaquin Valley than that area. It closest large city is Stockton. It is about 30-40min East of stockton on hwy 26. It is my understanding that the Fowlers lived in Rancho Calaveras, which is slightly southwest of Valley Springs (even closer to Stockton).
Look, to describe this best- it is rural FOOTHILL area... no pines or redwoods, but lots of oaks and rocks jutting out of the earth. Rattlesnakes galore. Think Little House on the Prairie, but add some hills. Foothills, not mountains. It gets really hot up there- 100F in summer, but it is below the snow line. Occasionally, they get snow, but it is not usual. Ebbets pass is MUCH higher, and closes at Bear Valley ski resort (hwy4) for the winter due to snow. The only way in for locals beyond that point is snowmobile. But that is HIGHER elevation- not really near valley springs.
Again I will say the area is rampant with drugs, dealers, and a degree of anonymity and lawlessness. And sweet, nice people, including wealthy people, looking to have affordable, picturesque large property. I know a lot of people who are from that area, and it is known that it is beautiful, but druggy country. They tend to keep to themselves, but if you stumble over their territory, you're done. People who are raised down in Stockton and other central valley towns, who have been around awhile, would avoid moving to certain areas up that way- Valley Springs, Angels Camp, San Andreas, Mokelumne Hill are a few. It's so sad, because there are such nice people/property up there, but mixed in with big time, low life drug dealers and don't even know it.
I am not trying to slam the area.. we go up to the Foothills often for wine tasting, cave exploring, b&bs, etc. It is beautiful, and the gold rush history is amazing. But it still seems to draw those who want to hide/fly under the radar. And the remoteness doesn't help with security.
Added: The Placerville link, IMHO, is prolly nothing. It is a major PITA to get from Valley Springs to Placerville. Stockton, if escaping by car, is a much faster, direct, anonymous route. Which is probably why early press said San Joaquin LE was involved. You leave the foothills and go down into the agricultural area/orchards of the central valley. Even more hiding places- Basically, you go 15min out of Valley Springs, and you are in Wesley Shermantine country. And look how well he hid their victims. :-( :-(
LE is correct- way too many places to hide. Too many crazies that melt into surroundings... just look back at Leonard Lake and Charles Ng- Calaveras County torture chamber nuts.