LONG LAKE DAM - AK00044-2651

Dam Name: LONG LAKE DAM
State: AK
Downstream Hazard Potential: L
Incident Type: Non-Failure
Incident Date: 09/11/2015
Incident Driver: Hydrologic/Flooding
Incident Mechanism 1: Gate/Valve Failure
Incident Mechanism 2
Incident Mechanism 3
Incident IDAK00044-2651
Incident DescriptionHeavy rain event (7.73 in 24 hrs & 2.8 in earlier in the week) resulted in a rainfall induced flood event during which a section of the wooden flashboards failed.
Named Hydrologic Event
EAP Enacted (Y/N) due to Incident
Fatalities (Number)0
Number of People Evacuated0
Number of Habitable Structures Evacuated0
Number of Habitable Structures Flooded0
Other Infrastructure Impacts
Economic Damages (in $)
Response
Volume released at failure (ac-ft)
Additional Remarks or Updates“The flashboards include a 20ft.x1ft. notch, near the south end of the dam, that will pass a nominal flow of 75 cfs. All additional flows will overtop the flashboards along the length of the dam. Based on the 1999 stability analysis, the flashboards are expected to fail at flood flows above 4500 cfs. This is a storm with a return interval of 10 years.
The dam is located in a very remote area and
there is no development downstream of the dam.
Owner TypeU
Dam TypeCNPG
Primary Purpose(s)H
EAPNR
Dam Height30 ft
Max Storage (ac-ft)147000.00
Surface Area (acres)1375.00
Year Completed1973
NID NumberAK00044
River NameLONG RIVER
Latitude58.1667
Longitude-133.733
Year Modified
Regulatory Agency(ies)AKDNR
Incident Time
Incident Duration
Incident Report ProducedYes
Information SourcesAK DNR
AttachmentsY