GMU 215 Sinlahekin
Border-country deer factory where a state wildlife area, Loomis State Forest and the Cascade crest stack mule deer and valley whitetail into one high-public-access unit.
WDFW Region 2 — District 6, Okanogan County (North Central WA) · Last reviewed 2026-07-12
Area
431
sq mi
Public land
73%
approx.
Elevation
1,000–7,800
feet
Motorized
moderate
access
Overview
GMU 215 "Sinlahekin" is a ~431-square-mile unit in northern Okanogan County running from the Sinlahekin/Similkameen valley bottoms near the Canadian border up into the eastern Cascades. It is unusually public for eastern Washington — roughly three-quarters open ground — anchored by the Sinlahekin Wildlife Area (Washington's oldest state wildlife area), the adjacent Chopaka Unit of the Scotch Creek Wildlife Area, the sprawling WDNR Loomis State Forest, and Okanogan-Wenatchee National Forest along the west. Mule deer are the headline animal, part of District 6's large migratory herd, with a strong valley whitetail population layered underneath and good bear, cougar and turkey opportunity. The far western edge sits inside the North Cascades grizzly recovery zone.
Terrain
A steep transition from the Sinlahekin/Similkameen valley floors and eastern scablands (~1,000 ft) up through timbered benches to rugged 7,000-ft-plus peaks in the northern and western high country. South-facing slopes and open shrub-steppe dominate the lower southern tip; heavy conifer and rock cover the crest.
Cover: Bunchgrass and sagebrush shrub-steppe with bitterbrush and serviceberry on the valley slopes and coulees; ponderosa pine and Douglas-fir on the mid benches grading into denser mixed conifer, old growth and subalpine timber up high; riparian brush and aspen in the creek bottoms.
Landmarks: Sinlahekin Wildlife Area (Washington's oldest state wildlife area, valley core) · Sinlahekin Creek and Valley · Chopaka Unit of Scotch Creek Wildlife Area / Chopaka Mountain · Palmer Lake and the Similkameen River (north) · Toats Coulee drainage · Cecil, Sarsapkin and Sinlahekin creek drainages (west) · Loomis State Forest (WDNR, western uplands) · Canadian border (northern boundary)
Access
One of District 6's most public-friendly units — roughly 73% open ground. The Sinlahekin and Chopaka wildlife area units plus Loomis State Forest and adjacent National Forest give walk-in and drive-in access across most of the unit, with private ranch and orchard ground concentrated in the valley bottoms and along the eastern edge. Ownership is intermingled, so run onX/GPS before crossing fences. Road hunting off the valley and forest-road network is common in general season; deeper mule deer live above the roads.
Managers: WDNR Loomis State Forest, WDFW Sinlahekin Wildlife Area, WDFW Scotch Creek Wildlife Area (Chopaka Unit), USFS Okanogan-Wenatchee National Forest (western border), Private ranch/ag land (valley bottoms, eastern edge)
Access points: Loomis-Oroville Road and the Sinlahekin Valley road through the wildlife area · Toats Coulee Road / FS roads west into Loomis State Forest and the National Forest · Palmer Lake / Chopaka Lake access on the north end · Forest Service road network off the western Cascade crest (walk-in above gates)
Species notes
Mule Deer
common qualityThe primary target and part of District 6's large migratory mule deer herd. Bucks summer high in the northern and western mountains and drop into the valleys and south-facing slopes as snow pushes them down. WDFW steers late-season permit hunters to south-facing slopes in the Toats Coulee drainage, the open portions of the Sinlahekin Wildlife Area, and the Cecil, Sarsapkin and Sinlahekin creek drainages to the west.
- →Glass south-facing slopes and open benches at first and last light, then plan a stalk on bedded bucks.
- →In early general season hunt higher timber and basins near the crest; time a late permit hunt to the migration when deer stack on lower south faces.
- →Work the open shrub-steppe and coulee edges of the Sinlahekin and Chopaka units where deer feed at the timber/grass interface.
- →Cover ground and burn boot leather above the roads — the mature bucks separate from the road-hunted valley deer.
Whitetail Deer
common opportunityWhitetail are abundant on the Sinlahekin Wildlife Area and Chopaka Unit and concentrate in the Sinlahekin Valley and surrounding creek drainages, giving hunters a second deer option in the brushy bottoms and ag fringe. Densities are highest in the valley farm-forest edge; mature bucks hold tight in heavy creek-bottom cover.
- →Still-hunt or stand-hunt the brushy creek bottoms, aspen pockets and ag/timber edges of the Sinlahekin Valley.
- →Hunt the feeding edges at dawn and dusk, then set back in the cover deer retreat to during daylight.
- →Time the November rut for a chance at a mature valley buck moving in daylight.
Black Bear
common opportunityBlack bears are well distributed through the timbered mid and upper elevations and berry basins. Note the western edge of the unit falls inside the North Cascades grizzly bear recovery zone — carry bear spray and be certain of your target.
- →Glass avalanche chutes, old cuts, burns and berry fields in late summer and early fall.
- →Hunt the timber/meadow edges and green-up along creek drainages.
- →Learn to distinguish black bears from grizzlies before hunting the western high country.
Cougar
common opportunityHealthy cougar numbers follow the strong deer base across the unit's timbered country. Mostly taken incidentally by deer hunters or with fresh tracking snow.
- →Cut timber-road and ridge edges for tracks after fresh snow.
- →Hunt near winter deer concentrations where cats follow the herds.
Pro tips
- →Use the high public share — pull off the valley road and hunt above the gates and roadless benches where pressured bucks live.
- →Late in the season, glass south-facing slopes in Toats Coulee and the west-side creek drainages for migrating mule deer.
- →Hunt whitetail and mule deer as two different games: bottoms and ag edges for whitetail, open high slopes for muleys.
- →The Sinlahekin and Chopaka wildlife-area units offer some of the easiest legal foot access in the unit — learn their boundaries.
- →Carry bear spray on the western edge and be sure of your target; it is inside the North Cascades grizzly recovery zone.
Watch out for
- !Intermingled private ranch/orchard ground in the valley bottoms and along the eastern edge — verify ownership before crossing.
- !North Cascades grizzly recovery zone on the western edge — grizzlies are possible; misidentification is a legal and safety risk.
- !Upper forest and Loomis roads snow shut early; a storm can strand vehicles and close access mid-hunt.
- !Fire-closure potential in dry years across the timbered and shrub-steppe country.
- !Canadian border along the north boundary — do not cross.
Logistics
Base out of Tonasket or Oroville for fuel, groceries and lodging; Loomis is the closest hamlet to the valley core. Dispersed camping is available on the National Forest and Loomis State Forest, and the Sinlahekin Wildlife Area has designated campsites. Cell service is spotty to nonexistent in the western drainages — download offline maps. Forest and valley roads are gravel and can turn greasy when wet or snowed in.
Nearest towns: Loomis, Tonasket, Oroville, Nighthawk, Riverside
Seasons & regulations
This page carries no season dates or regulations. Get current rules from the official Washington sources:
Research sources: WDFW District 6 Hunting Prospects (Okanogan County) · GOHUNT — Washington Unit 215 Sinlahekin profile · HuntScore — Deer Hunting in Washington's Sinlahekin GMU 215
FAQ
- How big is GMU 215 in Washington?
- GMU 215 (Sinlahekin) covers about 431 square miles, ranging from roughly 1,000 to 7,800 feet in elevation. Area is computed from the unit boundary polygon.
- How much public land is in GMU 215?
- Approximately 73% of the unit is public land. Primary managers: WDNR Loomis State Forest, WDFW Sinlahekin Wildlife Area, WDFW Scotch Creek Wildlife Area (Chopaka Unit), USFS Okanogan-Wenatchee National Forest (western border), Private ranch/ag land (valley bottoms, eastern edge). Always verify ownership boundaries on the ground.
- What species does the catalog list for GMU 215?
- Mule Deer, Whitetail Deer, Black Bear, Cougar. For seasons, tags, and regulations, use the official Washington agency resources linked on this page — this page carries no regulatory information.
Put GMU 215 on your map.
Boundary lines, public/private ownership, topo, and offline maps for this unit — in Baseline Maps, free for 14 days.