GMU 505 - Mossyrock, Washington

Mostly flat to rolling topography in the Cowlitz River lowlands with transition to steeper, rugged terrain on the eastern ridgelines above the Tilton River drainage. Elevation ranges from roughly 100 ft at the Cowlitz River bottom to approximately 2,800 ft on the eastern ridgeline near Bellicum Peak (2,310 ft). The landscape is a patchwork of small private farms, rural residences, second-growth Douglas-fir and western red cedar timberlands, and riparian corridors along the Cowlitz River, Mayfield Lake, and Riffe Lake (Riffe Reservoir on the Cowlitz). The eastern fringe approaches the Gifford Pinchot National Forest transition zone but the unit itself is dominated by lower-elevation valley and foothill habitat.

Access is the primary challenge in GMU 505. Approximately 20% of the unit is public land (Cowlitz Wildlife Area units at Peterman Hill and Swofford Pond, plus scattered DNR state forestland); roughly 45% is industrial timberland (Rayonier, Weyerhaeuser, Manulife/Hancock, and small private timber holders); and about 5% is urban/suburban. The Peterman Hill Unit of the Cowlitz Wildlife Area (~6,840 acres) along the western border is the most significant publicly accessible block and is the primary recommended hunting area for deer. State Routes 12 and 505, Winston Creek Road, Peterman Hill Road, and the Weyerhaeuser 1900 mainline are the primary access corridors. Private timberland operators including Rayonier have very limited or permit-required access; Weyerhaeuser motorized permits run $250-$400/year. Fire-danger closures may restrict vehicle access on private timberlands August through October.

Dominant vegetation is second-growth Douglas-fir and western red cedar with bigleaf maple and red alder in riparian areas. Understory includes sword fern, salal, Oregon grape, and elderberry. Agricultural clearings, active and regenerating clearcuts, and wetland edges around Riffe Lake provide the browse and forage that concentrate deer. Ruffed grouse habitat is rated good; waterfowl habitat along the lakes is modest.

Black-tailed deer move between the agricultural bottomlands and the timbered hillsides on a classic edge-habitat pattern. Deer concentration is highest along field edges, clearcuts, and the riparian corridors around Riffe and Mayfield lakes. Elk numbers are limited — the unit holds a small resident elk population with little seasonal migration into higher Cascade drainages given the low-elevation character of the unit. Black bear use the second-growth timber and berry patches in the transition zone. Cougar follow deer and are incidentally encountered; most cougar harvest in the district comes from opportunistic encounters during deer or elk seasons.

GMU 505 is one of the top five District 10 units for modern-firearm general-season buck harvest (340 bucks/year 5-yr avg, 29.0% hunter success rate, 2020-2024). Elk opportunity is limited — only 11 elk harvested per year on average with a 5.8% success rate (2020-2024), but a 20-permit antlerless elk special hunt (modern firearm, approx. Nov. 6-17) provides an additional drawing opportunity. General elk season allows 3-point-minimum or antlerless bulls. Black bear harvest averaged 5-14 bears/year 2022-2024 with modest 3-8% success. Cougar season runs Sept. 1 through March 31 (or until harvest cap met in the applicable Cougar Hunt Management Unit). Late archery and late muzzleloader deer seasons (Nov. 25-Dec. 15) allow any deer and overlap with late elk archery/muzzleloader seasons. No wilderness area restrictions within the unit boundary itself; the nearby Mt. St. Helens National Volcanic Monument special permit elk hunts (Mudflow, Pumice Plain, Mt. Whittier, Norway Pass, Upper Smith Creek elk areas 5099+) are in adjacent GMUs 522/524, not in 505. Treacherous angler access hoof disease (TAHD) program encourages harvest of limping elk in 500-series GMUs.