The lake was formed about 20,000 years ago when rising magma encountered groundwater resulting in violent steam explosions. The resulting explosions formed a broad shallow crater, which later filled with water.
This site is a popular swimming and picnicking area in the summer months. There is a boat ramp here for non-motorized boats.
PLEASE NOTE: This area is one of the few recreation sites on the Forest where DOGS ARE NOT ALLOWED because of safety and sanitary issues.
The two primary reasons that dogs are not allowed in the swimming area are sanitation and safety concerns related to the high numbers of people, including young children, who visit the lake. Sanitation is a concern because no outlet exists for the small lake and water quality becomes an issue, especially later in the season as the water warms.
If you plan to go to visit South Twin Lake, the Forest Service encourages you to leave your dog at home or visit another lake where dogs are allowed. Suttle Lake, located on the Sisters Ranger District, offers four day use areas where dogs are welcomed.
People may be fined $100 if they bring onto or possess a dog in a swimming area where dogs are prohibited (36 CFR 261.17(k)).
Recreation Fee Site: Parking at this site requires a recreation pass. Passes are available at this site, but can also be purchased from Forest Service offices or vendors. Please check here for more information about recreation passes and where they can be purchased.
Acceptable passes include:
- $5 Day Pass
- Northwest Forest Pass
- Interagency Annual Pass
- Interagency Senior Pass (America the Beautiful, Golden Age)
- Interagency Access Pass
- Interagency Military Pass
- Every Kid in a Park Pass
- Northwest Forest ePass
