Black Diamond Hill is a prominent highpoint in East King County, just east of the small town of Black Diamond. At this time, this access is posted Private Property. According to King County records, it is owned by the Weyerhaeuser Real Estate Division. In 2012, signs were up selling the property, so who knows what the future holds. It's possible the summit was used as a lookout prior to 1937 (see bottom of page).
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Black Diamond Hill

Distance: 1.5 miles
Summit Elevation: 1,270 feet
Elevation Gain: 500 feet
Access: Paved
Access:
The Basement
From Black Diamond, turn east on Lawson Street which becomes SE Green River Gorge Road. Follow it NE, then E, then SE. Look for the second gate on the right, just before crossing a small bridge. If you hit 290th Ave SE, turn back. Park in the turnouts on the north side of the highway a bit east of the gate.

Route:

Hike the road behind the gate as it slowly climbs southeast. After a few stream crossings, the road eventually reaches a minor saddle. Here is a 4 way intersection. Take the first right, on the least used road of the four. This road switchbacks climbing slowly but eventually reaching the saddle between the two summits. At that Y, go left for the summit with a view, the eastern summit. The right summit didn't seem higher and it certainly has nothing to offer. The highest spot was just inside the woods from the summit landing, on an ATV trail that drops down the other side of the mountain.
Washington Hiking
McDonald Mountain black diamond hill Sugarloaf Mountain black diamond hill forest road storm damage black diamond map
Sugarloaf Mountain Trip Report
Sugarloaf Mountain
The road walk
The road walk going bad
McDonald Mountain
NE from the east summit
The old landing on the east summit
Former Lookouts
Black Diamond Hill Lookout
It seems the hill was used as a lookout at some point based on information from the benchmark located just below the summit. Benchmark SX1344 located at N 47 18.853 W 121 57.632 (NAD 83) Altitude: 1204
Documented History (by the NGS)
1.1.1937 by WAGS (MONUMENTED)
DESCRIBED BY WASHINGTON GEODETIC SURVEY 1937 STATION IS ABOUT 3/4 MILE W OF FRANKLIN (AIR LINE) AND 100 YARDS N OF GROVE OF FIRS ON HIGHEST POINT OF THE HILL WHICH IS THE NE EDGE OF HILL ABOVE AND S OF THE W END OF PASTURE. STATION AND REFERENCE MARKS ARE STANDARD STATE SURVEY DISKS WEDGED IN DRILL HOLES IN BOULDERS. STATION IS REACHED AS FOLLOWS--FROM CHAPMANS UNION SERVICE STATION IN FRANKLIN GO S 0.4 MILE, TURN RIGHT AND FOLLOW MAIN TRAVELED ROAD 1.5 MILES TO HOUSE AND FARM BUILDING, CONTINUE 100 YARDS TO WHERE THERE IS A TURN INTO THE FIELD, 50 YARDS W OF TURN THERE IS A TRAIL GOING UP HILL. TAKE TRAIL COMING OUT AT TOP OF HILL BY HOLLOW CEDAR STUMP THAT HAS BEEN USED AS A LOOKOUT. STATION IS 104 FEET E OF STUMP.
1.1.1966 by BPA (MONUMENTED)
RECOVERY NOTE BY BONNEVILLE POWER ADMINISTRATION 1966 THE STATION RECOVERED IN GOOD CONDITION. THE TIMBER HAS GROWN AT THIS SITE AND IT WILL TAKE A CONSIDERABLE AMOUNT OF CLEARING FOR A LINE OF SIGHT OUT IN ANY DIRECTION.
Note: Benchmark triangle just down from the NE corner of summit area