Culmback

Culmback is a rockfill dam located in Snohomish County, Washington, built in 1983. It carries a High hazard potential classification and has a satisfactory condition assessment.

About Culmback

The primary purpose of Culmback is hydroelectric. The dam generates hydroelectric power by channeling water through turbines, converting the energy of flowing water into electricity. The dam is owned by Pud #1 Of Snohomish County, Wa (public utility). It impounds the Sultan River, Skykomish River near Sultan, Wa.

The dam stands 262 feet tall and stretches 640 feet across, creates a reservoir covering 1,870 acres, has a maximum storage capacity of 193,440 acre-feet, and collects water from a drainage area of 68 square miles. Completed in 1983, the structure is 43 years old.

This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 05/14/2021.

At 262 feet, this dam is taller than 99% of all dams in the United States.

Living Downstream

If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Washington dam safety program can provide more specific information about emergency planning for this structure.

Search for dams near your address to see all dams in your area with hazard classifications and safety data.

High HazardSatisfactory ConditionEmergency Action Plan: Yes

Location

StateWashington
CountySnohomish
Nearest CitySultan, Wa
River/StreamSultan River, Skykomish River
Coordinates47.97492, -121.68600

Physical Characteristics

Dam TypeRockfill
NID Height262 ft
Dam Height262 ft
Dam Length640 ft
Year Completed1983 (43 years old)

Storage & Hydraulics

NID Storage193,440 acre-ft
Max Storage193,440 acre-ft
Normal Storage153,260 acre-ft
Surface Area1,870 acres
Drainage Area68 sq mi
Max Discharge57,132 cfs
Spillway TypeUncontrolled

Ownership & Safety

PurposeHydroelectric
OwnerPUD #1 of Snohomish County, WA
Owner TypePublic Utility
Hazard ClassificationHigh
Condition AssessmentSatisfactory
Last Inspection05/14/2021
Emergency Action PlanYes

Identifiers

NID IDWA00208
Federal IDWA00208
More InfoState Dam Safety Program

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