Elevation: 5,896 ft
This peak is not in the book.
This somewhat-isolated Boise Mountain summit is a great destination for hikers in the spring. Grape Mountain sits east of the Irish Creek boat ramp on Arrowrock Reservoir. It is the highest point on the West End of the land that separates the Middle and South Forks of the Boise River. A road (gated and closed) leads to the summit. The peak was burned over at some point in the past. The forest is recovering nicely on the North Slopes. The peak is approachable from the east via Slide Canyon Road [(C)(1)] that connects the Middle Fork Boise River Road [(C)(1)] and the Upper Blacks Creek/South Fork Boise River Road [(G)(1) and (1.1)].
Follow the twisting, rough Middle Fork Boise River Road from ID-21 past Lucky Peak and Arrowrock Reservoir. Turn onto Slide Gulch Road about 8 miles past Cottonwood Road. You will cross a pass in 3.5 miles. Descend 1.7 miles from the pass and turn west/right onto an [unsigned] dirt road and follow this road for 1.0 miles until you reach the gate closing on the road that leads to the summit.
I recommend climbing the peak via the road. The peak’s slopes are mostly open for cross-country travel but the road offers an easy, albeit long, walk to the summit. My GPS watch recorded a 9.3-mile round-trip journey. A notation in the summit register reported that another GPS calculated the route at 5.5 miles one way. I doubt that either figure is accurate. If you want to try something different, Zach Vickery climbed the peak from the West after kayaking across Arrowrock Reservoir.
See John Platt’s trip report for additional access information.