GMU 372 Rattlesnake Hills
Hanford-fringe elk — a 2,400-head herd that beds on a closed nuclear reservation by day
WDFW Region 3 — South Central (District 4, Benton/Franklin) · Last reviewed 2026-07-12
Area
1,255
sq mi
Public land
15%
approx.
Elevation
400–3,600
feet
Motorized
limited
access
Overview
GMU 372 Rattlesnake Hills wraps the shrub-steppe ridges north of the Tri-Cities around the access-restricted Hanford Site and Hanford Reach National Monument. It is the heart of the Rattlesnake Hills sub-herd of the Yakima elk herd — a January 2024 survey estimated 2,497 elk, far over the 350-animal objective — but harvest is genuinely hard because the herd knows to retreat onto the closed federal Hanford lands during daylight in hunting season. Most of the rest of the unit is private ag (vineyards, orchards, dryland wheat) with only a few WDFW, BLM, and DNR pieces open to the public, so success hinges on private access or drawing one of the landowner-coordinated permit hunts.
Terrain
Long east-west shrub-steppe ridges — the Rattlesnake Hills and Rattlesnake Mountain (~3,500 ft, itself on closed Hanford ground) — dropping to the Columbia's Hanford Reach and to irrigated valley floor. Treeless, open, and dry.
Cover: Native bunchgrass and big-sagebrush shrub-steppe on the ridges and monument, transitioning to dryland winter wheat, CRP/SAFE grass cover, and irrigated vineyards, orchards, and row crops on the lower private ground. Cheatgrass carpets burned areas.
Landmarks: Rattlesnake Mountain · Rattlesnake Hills · Hanford Reach National Monument · Hanford Site (closed) · Columbia River / Hanford Reach · Yakima River (west edge)
Access
Access is the whole game here and it is tight. The core elk range — Rattlesnake Mountain, the ALE Reserve, and most of the monument — is closed federal Hanford land with no public hunting; the elk use it as a daytime refuge. Public hunting is limited to WDFW's Thornton and Rattlesnake Slope units of the Sunnyside Snake River Wildlife Area (open during modern firearm season, high demand) plus scattered BLM and DNR parcels — know exactly whose ground you're on. The realistic way onto the good private elk ground is the Blackrock Ranches and Silver Dollar special permit hunts in Elk Area 3722, where drawn permit holders get a one-day landowner-coordinated hunt (youth, disabled, quality-bull, and antlerless permits). Corral Canyon (Elk Area 3721) has a disabled permit coordinated through the Region 3 office.
Managers: U.S. DOE / USFWS Hanford Reach National Monument (closed), Private ag (vineyards, orchards, wheat), WDFW Sunnyside Snake River Wildlife Area (Thornton & Rattlesnake Slope units), BLM, WA DNR
Access points: Sunnyside Snake River WA — Thornton Unit · Sunnyside Snake River WA — Rattlesnake Slope Unit · BLM / DNR parcels along the Rattlesnake Hills · Blackrock Ranches / Silver Dollar permit-hunt access (drawn only)
Species notes
Rocky Mountain Elk
common qualityThe Rattlesnake Hills sub-herd of the Yakima elk herd numbers roughly 2,500 animals and is well over objective, but it beds on the closed Hanford reservation by day and only filters onto huntable ground at the margins. Best real chances are the Blackrock Ranches / Silver Dollar landowner permit hunts (Elk Area 3722) and the WDFW Rattlesnake Slope / Thornton units.
- →Treat this as an access problem first — draw a Blackrock/Silver Dollar permit or lock in private permission well ahead of season
- →Hunt the edges of the closed monument at first and last light when elk move to and from refuge and forage crops
- →On the WDFW units, expect crowds during modern firearm season and hunt away from parking
- →Success tracks forage conditions on the Hanford Site and the crops just outside the fence
Mule Deer
limited opportunityMule deer are present but there is little public land open to hunt them in northern Benton County. Deer Area 3372 (Sunnyside) offers an early muzzleloader opportunity; otherwise it's scouting the WDFW units, BLM/DNR scraps, or private access.
- →Scout the Thornton and Rattlesnake Slope units and any BLM/DNR parcels before the opener
- →Glass shrub-steppe draws and CRP edges at dawn and dusk
- →Chase the early muzzleloader Deer Area 3372 window if you can
- →Line up private permission early — the best deer ground is locked up
Whitetail Deer
transient lowWhite-tailed deer make up under one percent of deer on district surveys; WDFW offers a whitetail season only so hunters can legally take one if encountered during mule deer season.
- →Watch riparian brush and cropland edges near water where the odd whitetail holds
- →Treat any whitetail as an incidental, not a target
Cougar
transient lowCougars occur at very low density following deer and elk through the ridges and river breaks.
- →Cut tracks in snow along the Rattlesnake Hills breaks and river corridor
Pro tips
- →This is an access hunt: put in for the Blackrock Ranches / Silver Dollar permit hunts or secure private permission months in advance
- →Hunt the seams between the closed Hanford monument and open forage crops at the edges of light
- →The WDFW Rattlesnake Slope and Thornton units are your public fallback — expect competition and hunt off the roads
- →Verify land ownership constantly; closed federal, private ag, and small public parcels are interwoven with no obvious lines
- →Bring water and fire discipline — this is the hottest, driest corner of the state
Watch out for
- !The Hanford Site, ALE Reserve, and Rattlesnake Mountain are closed federal land — no hunting, and the elk know it's a refuge
- !Very little public land; trespass risk is high in the patchwork of private ag and closed federal ground
- !High demand and crowding on the small WDFW units during modern firearm season
- !Fast cheatgrass wildfires and burn closures
- !Extreme dry heat and no water — plan accordingly
Logistics
I-82 and Hwy 224/225 rim the unit and the Tri-Cities (Richland, Kennewick, Pasco) supply everything within a short drive. This is the driest part of Washington (6–9 inches of precipitation a year) — carry water. Camping is limited; most hunters base out of town. Cell coverage is good near the highways and valley.
Nearest towns: Benton City, Prosser, Richland, West Richland, Sunnyside
Seasons & regulations
This page carries no season dates or regulations. Get current rules from the official Washington sources:
Research sources: 2025 District 4 Hunting Prospects (Benton & Franklin Counties), WDFW · The Rattlesnake Hills (Hanford) Elk Herd Strategic Management Plan, WDFW · WDFW Game Management Units
FAQ
- How big is GMU 372 in Washington?
- GMU 372 (Rattlesnake Hills) covers about 1,255 square miles, ranging from roughly 400 to 3,600 feet in elevation. Area is computed from the unit boundary polygon.
- How much public land is in GMU 372?
- Approximately 15% of the unit is public land. Primary managers: U.S. DOE / USFWS Hanford Reach National Monument (closed), Private ag (vineyards, orchards, wheat), WDFW Sunnyside Snake River Wildlife Area (Thornton & Rattlesnake Slope units), BLM, WA DNR. Always verify ownership boundaries on the ground.
- What species does the catalog list for GMU 372?
- Rocky Mountain Elk, Mule Deer, Whitetail Deer, Cougar. For seasons, tags, and regulations, use the official Washington agency resources linked on this page — this page carries no regulatory information.
Put GMU 372 on your map.
Boundary lines, public/private ownership, topo, and offline maps for this unit — in Baseline Maps, free for 14 days.