Coho Day Use Area is the public picnic and swimming shore at Coho Campground on the west side of Wynoochee Lake, a reservoir in the Olympic National Forest about 35 road miles north of Montesano. The Forest Service lists it as the Coho Day Use/Picnic Area, and the campground around it is run by a concessionaire for the Hood Canal Ranger District. The lake was created in 1972 when the Army Corps of Engineers finished Wynoochee Dam, which the City of Aberdeen owns and Tacoma Power runs for hydropower. The swim shore sits in the lake's southwest corner, a short walk north of the dam, with forested ridges rising on every side.

From US 12, turn north on Wynoochee Valley Road about a mile west of Montesano. It becomes Forest Road 22, now paved most of the way. After roughly 35 miles, stay left on FR 22 at the big junction, then turn right on Forest Road 2294 and drive about a mile to the campground. Park in the day use lot inside the campground; a dirt path drops from there to the shoreline near the picnic tables by the dam. A second route comes in from Highway 101 near Shelton by way of Matlock, but parts of it are still gravel. Nothing is for sale at the lake (no gas, no store), so fill the tank in Montesano.

This is a cold mountain reservoir fed by the upper Wynoochee River and the creeks coming off the southern Olympics, so expect it to feel cool even in August. None of the managing agencies lists a lifeguard or a developed sand beach. Swimmers wade in from the natural shoreline and choose their own depth. Recreation.gov and Tacoma Power both point swimmers to this stretch of shore near the dam, and the Forest Service lists swimming at Coho. Floating log booms cross the water in front of the dam; stay well up the lake side of them and away from the spillway. The boat launch is a few hundred feet north, so watch for paddlers and boats coming and going.

Day use is free. The Forest Service charges $5 a day only to launch a boat, and its Wynoochee Lake Shore Trailhead page inside the campground says no fees are required to park. Overnight sites cost extra and are booked through Recreation.gov. The campground runs from about mid-May to the start of October, and the Forest Service closes seasonal gates on Forest Road 2294 in the fall, so plan a visit for late spring through September. Check Tacoma Power's lake page for the launch status before bringing a trailer. The Coho ramp has been closed to trailered boats at times, while kayaks, canoes and other car-top boats can still hand launch.

Coho also has flush toilets and drinking water during the season, a group picnic area with stoves, and the half-mile Working Forest Interpretive Trail, which starts in Loop B. The 16-mile Wynoochee Lake Shore Trail, a National Recreation Trail open to hikers and mountain bikes, circles the lake from here. At the dam there's a vista overlook with exhibits and a view down into the river gorge, and Tacoma Power gives free tours of its powerhouse by appointment. Spoon Creek Falls and Wynoochee Falls are short drives up the valley.