Shell Rock Milldam

Shell Rock Milldam is a rockfill dam located in Butler County, Iowa, built in 1928. It carries a Low hazard potential classification.

About Shell Rock Milldam

The primary purpose of Shell Rock Milldam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Shell Rock River Imp Comp (local government). It impounds the Shellrock River near Shell Rock.

The dam stands 7 feet tall and stretches 221 feet across, creates a reservoir covering 45 acres, has a maximum storage capacity of 229 acre-feet, and collects water from a drainage area of 1,752 square miles. Completed in 1928, the structure is well-established, with more than 75 years of service.

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 09/22/1989. That was over 36 years ago.

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Low HazardNot Rated ConditionEmergency Action Plan: Not Required

Location

StateIowa
CountyButler
Nearest CityShell Rock
River/StreamShellrock River
Coordinates42.71190, -92.58210

Physical Characteristics

Dam TypeRockfill
NID Height7 ft
Dam Height7 ft
Dam Length221 ft
Year Completed1928 (98 years old)

Storage & Hydraulics

NID Storage229 acre-ft
Max Storage229 acre-ft
Normal Storage152 acre-ft
Surface Area45 acres
Drainage Area1,752 sq mi
Spillway TypeUncontrolled

Ownership & Safety

PurposeRecreation
OwnerShell Rock River Imp Comp
Owner TypeLocal Government
Hazard ClassificationLow
Condition AssessmentNot Rated
Last Inspection09/22/1989
Emergency Action PlanNot Required

Identifiers

NID IDIA01293
Federal IDIA01293
More InfoState Dam Safety Program

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