Hill Annex No. 3 (south)

Hill Annex No. 3 (south) is an earth dam located in Itasca County, Minnesota, built in 1920. It carries a Low hazard potential classification and has a satisfactory condition assessment.

About Hill Annex No. 3 (south)

The primary purpose of Hill Annex No. 3 (south) is tailings. Tailings dams contain waste material from mining operations — typically a slurry of finely ground rock left over after valuable minerals have been extracted. These structures require ongoing monitoring because tailings can contain heavy metals and other contaminants. The dam is owned by Mndnr (private). It impounds the Swan River-tr near Local Residents.

The dam stands 65 feet tall and stretches 1,500 feet across, and has a maximum storage capacity of 910 acre-feet. Completed in 1920, the structure is over a century 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. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. The most recent inspection on record was 10/08/2019.

At 65 feet, this dam is taller than 96% of all dams in the United States.

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Low HazardSatisfactory ConditionEmergency Action Plan: Not Required

Location

StateMinnesota
CountyItasca
Nearest CityLocal Residents
River/StreamSwan River-tr
Coordinates47.30316, -93.25037

Physical Characteristics

Dam TypeEarth
NID Height65 ft
Dam Height65 ft
Dam Length1,500 ft
Year Completed1920 (106 years old)

Storage & Hydraulics

NID Storage910 acre-ft
Max Storage910 acre-ft
Normal Storage910 acre-ft

Ownership & Safety

PurposeTailings
OwnerMNDNR
Owner TypePrivate
Hazard ClassificationLow
Condition AssessmentSatisfactory
Last Inspection10/08/2019
Emergency Action PlanNot Required

Identifiers

NID IDMN00784
Federal IDMN00784
More InfoState Dam Safety Program

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