Pioneer Tailings Reservoir Report

Last Updated: December 5, 2025

Pioneer Tailings is a local government-owned earth dam located in St.


°F

°F

mph

Wind

%

Humidity

Summary

Louis, Minnesota, with a primary purpose of containing tailings. Completed in 1961, this dam stands at 25 feet in height and spans 2000 feet in length, with a storage capacity of 590 acre-feet. Situated near Lonsdorf Creek, this structure has a low hazard potential and has not been rated for condition assessment.

The dam is regulated by the Minnesota Department of Natural Resources, with state permitting, inspection, and enforcement in place. Despite being in operation for several decades, the last inspection occurred in August 2016, with an inspection frequency of 8 years. While the dam has not been assessed for condition, it is important to note that emergency action plans, risk assessments, and inundation maps have not been prepared or updated.

For water resource and climate enthusiasts, Pioneer Tailings presents an intriguing case study in dam management and regulatory oversight. With its historical significance dating back to the 1960s, this structure serves as a reminder of the importance of regular inspections, maintenance, and emergency preparedness in ensuring the safety and integrity of water infrastructure in Minnesota.

Year Completed

1961

Dam Length

2000

Dam Height

25

River Or Stream

LONSDORF CREEK

Primary Dam Type

Earth

Surface Area

63

Drainage Area

0.5

Nid Storage

590

Structural Height

25

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

25
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.