I got this report from a SuperTopo user: (thanks tom!)
Went up to Rainbow bouldering with our kids this past weekend. The dirt road on the North side Interstate 80 that leads up to the main bouldering area described in SuperTopo Lake Tahoe Bouldering page 165, is now marked private property. I don't know if just the road is private property of if the whole area around it is now considered private property. Since the private property signs were only on the closed gate on the dirt road, it seems unclear.
I have to add to the previous comments regarding weather or not this area (Rainbow) is private property ... it would seem that it is.
I was up in that area with some friends; and upon finishing slightly early on Sunday (we were at Shadow Boulder, near Split Rock ... had a good day), we figured on stopping by Rainbow to check it out on our way back down to the Bay Area. The thought had been to leave our gear in the car, take a quick look at some of the routes and perhaps get in a bit more climbing if we liked the look of things, or move on if we didn't see anything that caught our fancy.
We, too, saw the 'Private Property' and 'No Trespassing' signs on the dirt road - along with a locked gate - and believe me when I say the signs are many and obvious, the guy's done his best to convey his wishes to keep people out of the area. Stupidly, though, we decided to go check out the rocks anyway, and we walked around the gate and ignored the signs.
As we finished up our quick survey we saw a couple of trucks pull into the driveway for the road, by the locked gate and thought maybe it was good we had decided to leave at that point. Unfortunately the guys in the trucks had already seen us, though, and called us over as we tried to make our way back to the car.
Turns out that one of the guys was the property owner, and they had seen our SUV parked by the side of the road, gotten suspicious that someone might have gone around the gate, and then seen us up there when they checked. Needless to say, he was not too happy with us (that's probably an understatement) and probably would not take too kindly to his place continuing to be used as a climbing area - in all likelihood, it's probably a good idea if it gets left out of future revisions of the "Lake Tahoe Bouldering Book".
Frankly, I can't say I blame the guy for his frustration, he's done everything he can to reasonably try and keep people out (for whatever reason; but since he *is* the property owner, it is his right) - but apparently it's still happening. FWIW, we clearly weren't the first group he's had an issue with.
This happened at the main area on the north side of I-80; as we were leaving, we also checked the other smaller spot on the north side, and there are signs there too. I suspect the guy owns both of the spots, since he mentioned having purchased more than 100 acres recently. We didn't check the south side of the Highway, though.
Unfortunately, it looks like access issues have closed this spot. Sorry folks. :-(
the south area is actually pretty good with problems from VB to V11! right off the road and access is legit with huge parking pullouts and trails. even a little swimming hole.
the boulders are easy to find - one is on the west side of rainbow rd (VB-V11) on the slabs near the river and I80 and the other (the Sugarcube V0-V7/8) is on the east side - both are only about 1 minute from the road and have smaller boulders with more problems all around.