Bonneville Mountain is the unofficial name of the ridge that rises above Aneroid Lake and divides east and west Wallowa River. It's high point consists of two summits almost identical in height. The East summit holds the summit register and appears higher from most angles, but according to one fellow's note in the summit register the west summit is 10 ft higher.
Bonneville Mountain will not appear on any peakbagging lists due to its low "clean" prominence. However I consider it to be a very prominant landmark. It dominates the view to west from Aneroid lake, and is recognizable from many wallowa peaks.
This peak does not recieve many summits, about one party every year signs the summit register dateing back to 1988. This is probably do to it's intiminating appearence. Dispite it's jagged looks the summit can be obtained by a fairly easy class 3 scramble along the south ridge.
The best way to get to the start of the south ridge is by first hiking to Jewett Lake from Wallowa Lake Trailhead. To get to Wallowa lake from Portland take I-84 east toward the Dalles for about 260 miles, then take exit 261 onto OR-82 and follow it to the town of Joseph. The trailhead is found at the "Head of the lake" tourist area.
From the trailhead take the main pack trail to Aneroid lake. About a mile past Aneroid lake there is a split in the trail, take a right and follow it for about a mile (or untill you see Jewett lake) Jewett lake will be to your right (west).
A Northwest Forest Pass is required to park at the trailhead ($5/day or $30/year)
And a self-issued, free backcountry permit can be filled out at the trailhead.
There is good camping at Jewett lake.