Frenchman's Flat Day Use Area serves as the primary access point for Piru Creek WSR, offering a 60-space parking lot, vault toilets, picnic tables, and a non-motorized paved trail (Old Highway 99) for walking and bicycling along the river.

The site experiences high use during peak season weekends (April-October) with overflow parking available on roadside shoulders, and provides access to swimming, fishing, and whitewater boating opportunities, though boating is limited to winter months when dam releases are sufficient (typically 200-300+ cfs minimum).