The campground is easily accessible from HWY 26. A paved road leads all the way to the campground at the base of the mountain. Facilities include a vault toilet.
Something that I really liked is that the sites are very well secluded from one another. Each primitive site is tucked away and surrounded by trees and bushes. So you can't see the other campers. Which is the #1 goal of camping. Each site has a fire pit and picnic table.
The hike up to the top is tiring, if you're not feeling up to it there's a shorter hike that branches off the main trail around quarter mile in. The views along the way are incredible and the view from the top amongst the clouds is worth every step it takes to get there. The trail is 2.5 miles to the top and gains a little over 1,500 ft in elevation. Bring a raincoat in case the weather changes.
Making our way to Breitenbush Lake we passed lake after lake packed full of campers, not a single open campsite. By the time we were passing Ollalie Lake, the road was still totally drivable. Soon after the road got a lot worse, but I knew what I was getting into because I'd read some reviews. I drive a '16 Forester with off-road wheels and tires and we made it just fine. After a mile or two we arrived at Breitenbush Lake Campground and there were only two or three other people there. It was amazing to break away from the crowd. The road doesn't require very much clearance, as long as you have AWD and know how to handle your car off-road you will be just fine. That being said we ran into a couple driving an older Forester who came in from the other direction, from the west instead of going past Olallie Lake, who said they barely made it because the road was so bad. I would only recommend coming in from that direction if you have a truck with high clearance.
Warning: do not plan on swimming at Breitenbush Lake, it is located on the Warm Springs Reservation NOT within the Wilamette NF. There are stricter rules than at the other nearby lakes. If you wonder too far out of the campground you'll run into large yellow signs restricting you from trespassing onto the reservation.
Most of the sites were suited for car camping. At the southern end of the campground there were some walk-in sites as well, which is where we camped. These sites were also closest to the lake. All sites seemed to have a fire pit and there was vault toilet as well. If you continue walking through the walk-in sites on the south end you'll walk over a small footbridge, then you'll reach a second footbridge which has a pipe spurting cold drinking water.
If you ignore the No Trespassing signs and continue past the second footbridge the path splits several ways. Take the path second from the right and eventually you will come to a gravel parking lot. Stay to the left, at the south-eastern end, and you will find a trailhead. I'm not sure if it has a name but it is a section of the PCT. Depending on what season you go you will only pass PCT attempters or backpackers. If you have made it this far, congratulations you are not a tourist.
The hike is easily one of the best I have ever done, and I've done quite a few. You will steadily climb roughly 6 miles and experience some absolutely incredible views before reaching the top of Jefferson ridge. Here you will have a massive basin sprawling out in front of you sprinkled with several alpine lakes, and before you Mt. Jefferson.