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U.S. Forest Service

Pacific Southwest Region Viewing Area


Looking east on Diamond Mountain. East along Diamond Mountain crest. Photo by Craig Odegard.

Bluebell. Tall fringed bluebell. Photo by Don Lepley.

Frittilary on bitter cherry. A Mormon fritillary savors bitter cherry. Photo by Don Lepley.

Quartz outcrop at Bear Flat. Quartz outcrop at Bear Flat. Photo by Don Lepley.

Snowplant and low phacelia. Snowplant and low phacelia. Photo by Don Lepley.

Copeland's owl's clover. Copeland's owl's clover. Photo by Don Lepley.

West ridge of Thompson Peak. West ridge of Thompson Peak. Photo by Craig Odegard.

Diamond Mountains

Forest and Districts: Lassen National Forest, Eagle Lake Ranger District and Plumas National Forest, Beckwourth Ranger District

Description: The Diamond Mountains bound Long Valley and the Honey Lake basin for about 40 miles between Hallelujah Junction and Susanville. Their Susanville terminus is a mass of Sierran granodiorite, cut or capped in various places by a gamut of volcanic rocks and conglomerates, towering more than 3000 feet above Susanville on the valley floor, with a high point at Diamond Mountain summit (7738 feet). This is the northernmost reach of the Sierra Nevada, and the crestline east and west of the summit forms the border between the Lassen National Forest on the north and the Plumas on the south. Open areas along the crest offer sweeping views to Lassen Peak, Mt. Shasta, and the Warner Mountains to the north and, if the air is clear enough, the Sierra Buttes to the south.

Viewing Information: The mountains’ heights are clothed in a mosaic of upper montane conifer forests (with red fir and Jeffrey pine often prominent), groves of aspen, vegetation associated with small streams and wetlands, extensive alpine shrublands and dry meadows, and gravel- and rock-fields sporting plants specialized for such harsh habitats. Diverse habitats make for diverse plant species. Streams and wetlands support taller, more dramatic plants such as lady fern, giant red Indian paintbrush, tall fringed bluebell, largeleaf lupine, Sierra bog orchid, leopard lily, and the aptly named elephant’s head. Many slopes that have burned in the past now put up broad, golden-flowered displays of woolly mule-ears. Under aspen, mule-ears keep company with California waterleaf sprouting coils of violet flowers. Under conifers, you may see Coville’s toothwort, with white flowers and 3- or 5-fingered leaves. Forest openings may host eye-stoppers like snowplant as well as more modest plants like the purple-flowered low phacelia and pinkish Copeland’s orthocarpus. Among the sagebrushes and other shrubs of open slopes are Douglas’s buckwheat, with a circle of leafy bracts midway down the stem below the flowerhead, and Modoc hawksbeard, with dandelionlike flower heads darkened below by black hairs. Gravelly and rocky slopes and crests support less common plants, including Gray’s bedstraw, Brewer’s cliffbrake, and the rare Janish’s beardtongue and moss phlox. Many other species call this home as well. If the mountain wildflowers call you, June into July is the best time to investigate (and be sure to take lingering snowpack and weather conditions into consideration).

Safety First: Use extra cautions where visibility is limited or when traction is poor. Watch out for wildlife using the roads—they’re more at home here than you are! Walking off-road on the Diamond Mountains is also off-trail: be careful of rough or loose footing or obstructing brush. Because of the high elevation and exposure, solar radiation can be intense, weather changeable, winds fierce and effective temperatures very cold—dress and equip accordingly. Please do not pick plants - doing so may further endanger rare species - leave them undisturbed in their habitat so that you and others may enjoy them another day.

Directions: Two principal approaches to the summit areas are, for the west end, via the Gold Run Road (County Rd. 204) from Susanville or, for the east end, from Highway 395 via the Janesville Grade (Country Rd. 208). Both roads connect with Forest Road 28N02, which traverses the south (Plumas) slopes of the mountain. Two miles west of Thompson Peak, Forest Road 29N43 forks north from Road 28N02 and provides access to the north (Lassen) slopes of the mountain; the road then drops through private timberlands north of the crest to join the Gold Run Road. Maps can be purchased at local Forest Service offices or on websites of the Lassen National Forest or the Plumas National Forest.

Ownership and Management: USDA Forest Service, Lassen National Forest, Eagle Lake Ranger District (530) 257-4188, and Plumas National Forest, Beckwourth Ranger District (530) 836-2575.

Closest Town: Janesville and Susanville, California.