GMU 372 - Rattlesnake Hills, Washington

Large east-west trending ridge system anchored by Rattlesnake Mountain (elev. ~3,400 ft), rising ~2,000 ft above the valley floor. Unit spans elevation 350-3,400 ft across roughly 1,260 square miles. Terrain includes shrubsteppe slopes, basalt rimrock, coulees, and river breaks. The Yakima River borders the southwest; the Columbia River and Priest Rapids Lake define northern and eastern edges. The Hanford Reach National Monument occupies a major portion of the northern interior. Rolling channeled scabland features appear in the eastern margins. Upland habitats are Columbia Plateau Ecoregion shrubsteppe historically dominated by sagebrush, bitterbrush, and native bunchgrasses, now fragmented by invasive cheatgrass, dryland wheat, and irrigated agriculture in the Yakima River valley. CRP and SAFE program fields provide cover adjacent to croplands.

Approximately 17% public land. Primary public hunting areas: (1) WDFW Sunnyside Snake River Wildlife Area — Thornton and Rattlesnake Slope units provide the best deer scouting and hunting access within GMU 372; (2) Scattered BLM parcels in the checkerboard interior of the unit; (3) Washington DNR parcels. The Hanford Reach National Monument and Yakima Training Center (YTC) are closed to public hunting. Elk Area 3722 (Blackrock) and Elk Area 3721 (Corral Canyon) are largely private — hunters pursuing elk through these designated areas must use WDFW private land access programs (Hunt by Written Permission, Hunt by Reservation, Register to Hunt, Feel Free to Hunt) or win a special permit hunt. Deer Area 3372 (Sunnyside, Benton and Yakima counties) provides an early muzzleloader opportunity along the Yakima River from Prosser to Union Gap.

Columbia Plateau shrubsteppe: big sagebrush, bitterbrush, rabbitbrush, native bunchgrasses (bluebunch wheatgrass, Idaho fescue). Invasive cheatgrass is widespread and fuels frequent fast-moving fires; sagebrush recovery post-fire takes decades. Riparian corridors along the Yakima and Columbia rivers support cottonwood, willow, and dense shrub cover. Dryland wheat and irrigated crops (orchards, vineyards, row crops) in valley floors. CRP and SAFE fields provide transitional cover. The Hanford Site interior is largely undisturbed native shrubsteppe — one of the largest intact shrubsteppe landscapes in the Pacific Northwest.

The Rattlesnake Hills elk sub-herd (part of the Yakima Elk Herd) uses the Hanford Site and Hanford Reach National Monument as a daytime refuge and moves onto adjacent private lands and WDFW wildlife area units at night and in early morning, especially during hunting season. Herd was estimated at 2,497 animals in January 2024 — far above the 350-animal management objective. Elk numbers have grown dramatically since the 1980s. Harvest success correlates with forage conditions on the Hanford Site and availability of crops outside the restricted zone; hunters are more successful early in the season. Mule deer in the Rattlesnake Hills are a resident population with some movement to lower elevations in winter. White-tailed deer make up less than 1% of deer observed on surveys district-wide.

Access is the defining challenge of GMU 372. The elk herd is large and growing but the best habitat is on off-limits federal land (Hanford DOE site, YTC). Private land access for elk is high-demand; plan well ahead. Special permit hunts — Blackrock Ranches and Silver Dollar — are the best route to Hanford-adjacent private elk hunting; permits include youth, disabled, quality elk, and antlerless elk categories. For deer, the Thornton and Rattlesnake Slope units of Sunnyside Snake River WA are the most reliable public entry points. GPS-based land ownership mapping is essential to avoid trespassing in this checkerboard landscape. CWD testing not required for District 4 GMUs as of 2025-2026 season. Elk hoof disease (TAHD) not currently known in District 4 elk. Rattlesnake Hills is in WDFW South Central Region 3, District 4 (Benton and Franklin counties). District wildlife biologist: Jason Fidorra.