Cougar Hot Springs (Terwilliger Hot Springs) | Oregon Cascades

Nestled in a forest canyon of the Willamette National Forest, Terwilliger (Cougar) Hot Springs is a popular destination for all who enjoy bathing in a natural geothermal spa surrounded by a beautiful scenery of the old-growth forest.

There is a series of cascading soaking pools built up from the rocks and logs. Thermal water flows out of a small cove at a temperature of 116-degree Fahrenheit into the upper which is, also, the hottest pool and then cascades down to other five pools. Each descending pool is a few degrees cooler than that one above. The hot springs with blue crystal-clear water create a gorgeous contrast with the deep green color of the forest.

The hot springs can be accessible by an easy quarter-mile trail from the small kiosk. Pay a fee (only cash) and start your way to the scenic hot spring area.

No services and no drinking water are available. There are two compost toilets and a changing shelter near the pools. Also, there is a vault toilet at the parking area.

This is a day-use site, open from sunrise to sunset during the week. Every Thursday from 8 am to 12 pm pools are closed for cleaning and maintenance.

Be advised that the site gets crowded on weekends and holidays.

Officially by the Forest Service, the site is called Terwilliger Hot Springs, after one of the first settlers Hiram Terwilliger who found this site in the 1860s and used the hot mineral water benefits for decades. In 1906, he filed a mineral-rights claim but it was denied by the Forest Service.

Because of its proximity to the Cougar Reservoir, it is also known as Cougar Hot Springs.

The hot springs were an isolated area until the 1960s. Built by the US Army Corps of Engineers, the Cougar Dam and paved roads made the hot springs more accessible and, eventually, it became extremely popular.

Between the 1960s and 1990s, there were hundreds of people bathing and camping near the hot springs. In the summer months, it could be over a thousand people at the same time in this area.

The growth of visitors led to a number of problems including loud night parties, littering, drug dealing, and alcohol abuse, loitering and panhandling, and, finally, a murder that occurred in 1996.

In 1998 the Forest Service decided to charge a fee for a day-use and prohibit camping within 9 miles of the hot springs. The fee system, a night-closure policy, and an alcohol ban helped to make Cougar Hot Springs cleaner, safer, and more attractive for hot spring lovers.

Location: 55 miles east of Eugene • Cascade Mountains • Oregon • USA
Open: Year-round from sunrise to sunset
Development: Primitive
Clothing: Optional
Amenities: Changing shelter and compost toilets; Vault toilet at the parking area
Accommodations: No camping nearby is allowed; the closest campgrounds at the Cougar Reservoir is about 3.5 miles away
Hiking distance: 0.25 miles
Road Access: Any vehicle
Day-use: Yes with fees
Managed by: US Forest Service

Elevation: 1,700 ft (518 m)

Water T° (source): 116°F (47°C)
Water T° (pools): 95°F (35°C) to 110°F (43°C)
Water acidity level: Neutral (pH=7.76)
Springs type: Sodium Chloride
Flow rate: 29 gallon/min (110 l/min)
Chemical used: None

Average dissolved solids: 1,800 Mg/L

Cations

Sodium (Na) - 392 Mg/L
Calcium (Ca) - 225 Mg/L
Potassium (K) - 6.3 Mg/L
Boron (B) - 5.1 Mg/L
Lithium (Li) - 0.52 Mg/L
Magnesium - 0.1 Mg/L

Anions

Chloride (Cl) - 788 Mg/L
Sulfate (SO4) - 260 Mg/L
Silica (SiO2) - 50 Mg/L
Carbonate (CO3) - 21 Mg/L
Fluoride (F) - 0.8 Mg/L