Summary
This gravity dam was completed in 1962 and serves primarily for recreational purposes, with a storage capacity of 90 acre-feet and a normal storage level of 50 acre-feet. The dam has a height of 9 feet and a length of 220 feet, impounding the Ashippun River to create a surface area of 19 acres and a drainage area of 24 square miles.
Despite being classified as having a low hazard potential and fair condition assessment, Alderly Mill has state regulation and permitting in place, with regular inspections conducted by the Wisconsin Department of Natural Resources. The dam's spillway is uncontrolled and has a maximum discharge of 206 cubic feet per second, indicating moderate risk management measures. Located in a picturesque setting, the dam offers opportunities for outdoor recreation while also contributing to the local water resource management and climate adaptation efforts in the region.
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15-Day Weather Outlook
Year Completed |
1962 |
Dam Length |
220 |
Dam Height |
9 |
River Or Stream |
ASHIPPUN |
Primary Dam Type |
Gravity |
Surface Area |
19 |
Hydraulic Height |
7 |
Drainage Area |
24 |
Nid Storage |
90 |
Structural Height |
9 |
Hazard Potential |
Low |
Nid Height |
9 |
Seasonal Comparison
5-Day Hourly Forecast Detail
Nearby Streamflow Levels
Bark River At Nagawicka Road At Delafield
|
48cfs |
Rock River At Watertown
|
1690cfs |
Menomonee River At Menomonee Falls
|
117cfs |
Fox River At Waukesha
|
350cfs |
Rock River At Horicon
|
926cfs |
Little Menomonee River Near Freistadt
|
35cfs |
Dam Data Reference
Condition Assessment
SatisfactoryNo existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.
Hazard Potential Classification
HighDams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.
Alderly Mill
Ashippun Lake -- Access