Anderson Truck Trail
Anderson Truck Trail is now permanently closed and gated at the Alpine end just past the Viejas Mountain trailhead. Now a private road. No trespassing. :(
Anderson Truck Trail goes from Anderson Road in Alpine to Peutz Valley Road. 4WD and high clearance are required after the entrance road at the Alpine end. There are several side roads and mountain bike trails to explore along with a spectacular view of El Capitan Reservoir. When it turns south along El Capitan Reservoir it becomes a one track road suitable only for two-wheel vehicles. This is a public road in the western part of the Cleveland National Forest (Forest Route 15S30). Considering its proximity to San Diego it is surprisingly unknown among 4X4 enthusiasts. However it is popular with mountain bikers so expect to see some of them on the road.
Starting at the Anderson Road end, the road begins very easy and suitable for passenger cars before the rainy season. After 2 miles it gets gradually worse and may be a bit much for a passenger car. At 2.6 miles it gets suddenly difficult starting with some ruts that can be very deep. You will need 4WD and high clearance here. Shortly after the ruts and a sharp left you reach a "T" intersection. If you go straight the road becomes Anita Way. This goes about 3/4 mile before ending at private property. It can also be very rutted. Turn right at the intersection to stay on Anderson Truck Trail. Continuing to the west the road goes about 1.4 miles then turns south above El Capitan Reservoir. Here it becomes a single track all the way to Peutz Valley Road. There are some more challenges here as well as a great view of El Capitan Reservoir. Finding your way out may be problematic. First you will encounter the Great Wall of Bofus, a sheet metal barrier that barely passable. Beyond this you are on disputed property. It is apparently public land but the owner of the adjacent property claims ownership has been known to confront mountain bikers and to lay booby traps (the most recent reports are more than 10 years old though). This is who erected the wall. If you want to play it safe backtrack about 200 feet and take the steep trail to the top of the ridge and exit that way.
Yahoo Map Directions from San Diego (to Peutz Valley road end) 
KML Map for Google Earth
Difficulty: very easy (1) to difficult (4).
You can get a Subaru Forester through the ruts at the 2.6 mile mark but you will wish you had a low range and some serious lift. I found myself sliding sideways on three wheels at one point. After turning around (now uphill) it took several attempts to get through. I was beginning to wonder how much it was going to cost me to get towed out before one final push made it. I think off-road tires would have made all the difference here.
Update: getting through the ruts at the 2.6 mile mark was pretty hairy for me with no experience and an AWD crossover. I figured that for someone with experience and a real off-road vehicle it would be a Sunday drive. I guess it's not so "moderate" after all. Perhaps some volunteer maintenance would be in order. It's a public road close to town. It would be nice to see it in better condition. Further update: as of 2/8/2104 the above-mentioned ruts are much improved. However, the road gets a bit hairy after that.
In my lifted 1989 Suburban 4x4 the road passes some houses about 3.5 miles out and you will have to stay left to continue on the trail, otherwise to the right is private property, very private, like shotgun private. After the turn left down the road about a half mile he road starts getting a little challenging even for a 4x4 lifted truck. Further down the road continues to have occasional challenges for the 4 wheel enthusiast. Overall Some good four wheeling and great views of El Cap lake.
For my journey after reading what the Subaru forester guy wrote I pressed on now into the drive about an hour. I was looking for the exit to Peutz valley road. I came across a newer Chevy 3500 4x4 flipped over and ravaged. As we continued down into the valley we did finally come to Peutz valley road. It was however a locked gate, no way around. Fortunately nobody was home in the property blocking me from the road and I passed through on the property (Not recomended).
Although a nice trail, I have a feeling locals dont care for the offroad traffic as there was not many tracks. Plan on turning around at the end, but if you have the time its a decent trail.
I just went there for my weekend adventure (6/10/12) knowing that this trail is easy to moderate. If the Subaru Forester can manage to pass this trail, I can do it easy with my 2002 Jeep Liberty Limited Edition 4x4. First 4 miles is ok but after that the road is all wash out and it's really bad even I'm on L4WD I'm still sliding and got stuck several times. I need to jack my jeep up and put a rock under my tire. About 3/4 of the trail I need to stop and turn around coz its really bad. And the worst part is my radiator fan broke, hit my radiator and punch a hole. It's good it happened near the house of this generouse couple who help us tow all the way out the trail. So if you don't have a truck with a serious lift don't even try to go in here and if you do go in group. I learn my lesson in a hard way.
I just went in December 2013. Vehicle is a lifted Jeep Wrangler Rubicon with 35" tires. Be careful on this trail. There are ruts deep enough to come up to the windows of the lifted jeep. Most of the big ruts can be avoided, but not all. One bonus that I found. Mud. Lots of good mud holes to drive through. You can definetely get muddy on this trail. The road gets very narrow going past El cap. Some really good views of the lake. There are at least two wash outs on the road above the lake. Both of them have abandoned vehicles below them. Since the outboard track of the road appears to give way, I would not recommend driving in a heavy vehicle. Actually I don't think I would go this way again period. Not sure what conditions caused the road to give way and drop two vehicles down the mountain, but I wouldn't want to risk replicating them again.