I'm calling this route the East Ridge as it more or less comes up from Minam Lake on the east side of Brown Mountain, but it's not a real defined ridge and might also be considered the Northeast Ridge if you are looking at it on a Topo map. This is probably the easiest and most direct way to summit Brown Mountain. The west side is generally steep scree and who wants to mess with that. The East Ridge starts just a bit north of Minam Lake from Trail 1670 and heads generally west up a gentle open granite and meadow ridge to about 8100 feet. There you transition to loose basalt and you remember what state you are really in. You'll skirt a couple bands of basalt columns and then scramble up to the summit ridge where you'll cross over to the west side of the ridge for the final scramble to the summit.
I know everyone says the same thing about every summit but I'm telling you, the views are so flipping awesome. You can see most of the Wallowas from here including east to Sacajawea, Matterhorn and Aneroid Peaks; south to Eagle Cap and Glacier Peak and even Needle Point and China Cap. Plus, you are overlooking lakes, lush meadows with snaking streams and can see over to the Elkhorn Range as well. Directly north are Elkhorn Peak (not to be confused with the other range SE of here) and Glacier Mountain. It doesn't get much better than this.
The approach from the trailhead is probably around 3 hours in and the climb will take a couple hours at least. The descent will take you the rest of the day though because you will want to lounge in the meadows on the east side of this peak. I'm not kidding you. There are at least a half dozen you'll want to kick back and watch Nature's tv show for an hour, nap, snack, then realize that you need to get back down at some point. Enjoy the heck out of this one! It can be done as a day hike if you want but most will camp at Minam Lake and make an awesome weekend out of it.
See the Getting There section of the Brown Mountain page for directions to Two Pan Trailhead.
From the Two Pan Trailhead at 5606 feet, hike south following signs for the Lostine River Trails (the right fork out of the trailhead by the signage). After a short distance (about .15 miles), bear right onto Trail 1670 to Minam Lake. At 2.6 miles from the trailhead, you will come to a junction at 6425 feet. Fork left to signs for Minam Lake. At 4.15 miles from the trailhead, you will round the ridge coming down on your right from Glacier Mountain and start to have some views of Brown Mountain to your right.
If you are not heading in to camp at Minam Lake and are making this a dayhike, at 5 miles in and about 7300 feet, you can bear right and start heading up the ridge toward Brown Mountain. (See first photo below.) It's a gentle slope and treed here. This is also about the point, or close to it, where you will see an obvious tan dirt/sand flat campsite in the middle of the valley off about 40 yards from the trail. This makes an excellent spot to start heading up the ridge as you don't want to go too far south or you'll see the obvious granite cliffs on the south side of this ridge. You want to head up towards the summit on the gentle side of the slope inside the cirque.
If you are heading in to camp at Minam Lake, you still have about a half mile to go and 100 feet of elevation. You'll want to return to this spot to head up or you can try to pick your way up NW from the lake to the ridge staying to the right of the cliffs. It's also possible to get into the lower part of the cliffs and find breaks to scramble up through to gain the ridge.
(The above photo shows the point in the trail where you want to leave the trail and head cross country up onto the grey granite ridge running left to right in this photo. The further to the right, the easier it will be to gain the ridge. Note the flat campsite in the dirt center left in this photo. The high brown point above is the summit pinnacle.)
From Minam Lake head north through the campsites on the north side of the lake. The object is to gain the obvious ridge east of where they are granite cliffs. The closer you are to the Lostine River (flowing out of the lake to the north as a small creek), the easier this is going to be. If you are able to see an obvious open sandy campsite near the main trail, you can angle northwest from there into the bottom slopes of the East Ridge. As long as you can see the big cliffs on your left, you should be able to pick your way up through the granite blobs and forest as you ascend. You will want to stay as close to the cliffs on the south side of the ridge as possible as the north side of the ridge will slowly fall into a basin of meadows in the cirque created by Brown Mountain and Glacier Mountain. Ascend this ridge coming across small flat meadows on the way that are great for taking breaks.
(The above photo is just at about 8000 feet where you will transition from granite to basalt. You can see the first basalt column band through the dead trees left of center. Once you reach treeline, change your heading to skirt this on the left. It will peter out after a short distance.)
Above you will be the brown summit pinnacle looking like a castle guarded by short brown walls. Just keep heading towards this. At 8100 feet you will come to a large plateau/meadow area. The right side now falls down into the cirque will snowfields at its head. The left is a gentle plateau where you want to hang out and look for goats and elk. But keep going up to the brown wall.
(The above photo is above the trees as you reach the base of the first basalt band. Head left around this first rock band.)
You will skirt the lower basalt columns on the left (south) as they die out. Head straight up here and you will now start scrambling among brown blocks of fallen basalt.
(The above photo is just as you skirt the first basalt band (see it ending in the right side of the photo) looking up to the next.)
(The above photo is taken between basalt bands looking down at the meadowy plateau at the top of the East Ridge.)
As you look at the summit pinnacle now you will see another wall of basalt columns. Skirt that next band again to the left and you will see as it wraps around the left (south) side of the summit pinnacle a shallow groove heading up to the right of a thumb of rock sticking up just before you come to the summit ridge.
(The above photo is taken from south of the summit pinnacle in the meadow on top of the East Ridge almost to the cliffs on its south side. You can see the second basalt band at the base of the summit pinnacle. You will head up where the basalt band ends in a shallow groove - probably a goat path - up towards the notch in the main pinnacle on the right.)
Take this loose staircase that looks like a goat path (it probably is) up to the ridge and you will be between two basalt gendarmes.
(The above photo is taken from the notch in the summit pinnacle watching a climber come up the little Class 3 groove)
(The above photo shows the scramble up the groove from below.)
At the saddle between these gendarmes, you will now see over to the backside of the ridge. Downclimb about 20 feet staying on the upside of several small trees and snags until you can completely see the backside of this ridge. It may look like the gendarme to your right is the high point but it is not. Angle up and left where it is easiest scrambling (anything over Class 3 is off route) to the ridgeline and then pick your way north to the high point where there is a little cairn and enough room for 3 people and a dog (our party) to sit. Wonder about why no one has ever brought a register to sign up here.
(The above photo shows the backside of the summit ridge. The summit is behind me. The notch that you just scrambled up to is just out of sight in the right of this photo.)
(The above photo shows the scramble over to the summit (I am standing at it.) The notch is between the dark humps on the ridge in the right of the photo.)
(I'm standing on the summit looking north along the summit ridge to Glacier Mountain in the above photo.)
Approach is 5 miles and 1700 feet. From the trail to the summit is about 1.5 miles and 1650 feet. (Total round trip is 13 miles and 3350 feet. Add 1 mile and 100 feet if camping at Minam Lake.)
Descend the same route but take your time and enjoy the meadows in the cirque on your way down.
Nothing needed but a camera for the amazing views. Be cognizant of afternoon thunderstorms that develop regularly here. This is more like the Rocky Mountains than the rest of Oregon. Showers are common from about noon on during the summer and sometimes that means lightning.