Trillium Lake

Trillium Lake is an earth dam located in Clackamas County, Oregon, built in 1960. It carries a Low hazard potential classification.

About Trillium Lake

The primary purpose of Trillium Lake is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Oregon Department Of Fish And Wildlife (state). It impounds the Mud Creek near Welches.

The dam stands 21 feet tall and stretches 985 feet across, creates a reservoir covering 65 acres, has a maximum storage capacity of 380 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1960, the structure is well into its service life at over 50 years old.

This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. The most recent inspection on record was 06/12/2019.

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Low HazardNot Rated ConditionEmergency Action Plan: Not Required

Location

StateOregon
CountyClackamas
Nearest CityWelches
River/StreamMud Creek
Coordinates45.26731, -121.74231

Physical Characteristics

Dam TypeEarth
NID Height21 ft
Dam Height19 ft
Dam Length985 ft
Year Completed1960 (66 years old)

Storage & Hydraulics

NID Storage380 acre-ft
Max Storage380 acre-ft
Normal Storage353 acre-ft
Surface Area65 acres
Drainage Area0 sq mi
Max Discharge450 cfs

Ownership & Safety

PurposeRecreation
OwnerOREGON DEPARTMENT OF FISH AND WILDLIFE
Owner TypeState
Hazard ClassificationLow
Condition AssessmentNot Rated
Last Inspection06/12/2019
Emergency Action PlanNot Required

Identifiers

NID IDOR00350
Federal IDOR00350
More InfoState Dam Safety Program

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