Name of Waterfall

Rocky Brook Falls


Rocky Brook Falls is located near Brinnon, along the Dosewallips Road off Highway 101. The Dosewallips Road heads inland from Brinnon about 2/3 of a mile north of the bridge on Highway 101 across the Dosewallips River. Watch for signs for Olympic National Park. Follow the Dosewallips Road for three miles to the Rocky Brook Bridge, and park on the left on the far side. Follow the trail past the hydro facility to the falls in about 500 feet. The rocks at the base of the falls can be exceptionally slick if wet, so tread lightly.Rocky Brook Falls is among the tallest of the front-country waterfalls found on the Olympic Peninsula, and one of the easiest to access waterfalls on the Hood Canal side of the peninsula. The falls drop through a narrow gorge where Rocky Brook breaks over a hanging valley and pours into the Dosewallips River valley in spectacular fashion. The visible portion of the falls drops 229 feet in a narrow veiling horsetail type fall, with a nice pool at its base which is popular among locals for swimming during the summer months. Tucked in the gorge upstream of the main falls is at least one more tier which looks to drop perhaps another 75 feet (possibly more), but there is neither easy or developed access to that part of the falls.
Rocky Brook is the second largest tributary to the Dosewallips River after Silt Creek, draining an area of about 8-1/2 square miles and ranging from about 600 feet above sea level up to around 4200 feet or so. The basin receives heavy rain throughout the year, and a not insignificant amount of snow in the winter, so despite not having a terribly large basin the creek flows well all year long. This factor, plus the considerable height of the falls likely spurred the installation of a hydroelectric facility at the falls in 1986. Fortunately the falls are allowed to flow year round, and even with the diversion can still swell to an impressive volume after periods of heavy rain.
The diversion appears to occur perhaps a fifth of a mile upstream from the falls, and sends a portion of Rocky Brook into a penstock for most of the year to a small powerhouse near the base of the falls. A sign on the side of the powerhouse states the facility generates 446 feet of head (the elevation change between the diversion above the falls and the generators), which suggests that the upper tier(s) of the falls may be even taller than it lets on - topographic maps suggest the total height to be closer to 350 feet or so.We don't know how or when either the falls or the brook were named. The name of the falls has been in use for well over 100 years, and was likely adopted from the name of the stream. Because there aren't many streams in Washington referred to as a "brook", I suspect a settler from the eastern states probably named it at some point. At some point in the early 20th century (and perhaps earlier) the falls were known as Idlewild Falls. This name never made it to common usage it seems, as we've seen only a single citation of such.

Other Names

['Idlewild Falls']



IWC Rating (International Waterfall Classification)


Total Height (ft)


Tallest Drop


Number of Drops


Average Width


Average High Volume (Cubic ft per second)

35 cfs (7 months)

Average Low Volume (Cubic ft per second)

5 cfs (5 months)


77 degrees

Run (ft)


Watershed or Feeder Stream

Dosewallips River Rocky Brook