Wynoochee River

Total streamflow across the Wynoochee River was last observed at 964 cfs, and is expected to yield approximately 1,912 acre-ft of water today; about 72% of normal. Average streamflow for this time of year is 1,335 cfs, with recent peaks last observed on 2025-12-17 when daily discharge volume was observed at 22,850 cfs.

Maximum discharge along the river is currently at the Wynoochee River Above Black Creek Nr Montesano reporting a streamflow rate of 394 cfs. This is also the highest stage along the Wynoochee River, with a gauge stage of 27.62 ft at this location. This river is monitored from 3 different streamgauging stations along the Wynoochee River, the highest being situated at an altitude of 632 ft, the Wynoochee River Near Grisdale.

It originates in the Olympic Mountains and flows northwest into Wynoochee Lake, which is created by the Wynoochee Dam. The river then continues west and eventually flows into the Chehalis River near Aberdeen. The Wynoochee River is primarily used for hydroelectric power generation, with the Wynoochee Dam being the main source of power. The reservoir created by the dam is also used for recreational activities such as fishing, camping, and boating. The river has a rich history, with the Wynoochee Dam being built in the 1970s to provide power to the growing population of western Washington. The river also supports various agricultural activities along its banks. Despite the dam's benefits, it has had negative impacts on the river's ecosystem, including a decline in fish populations.