Lake Thunderbird Lower Dam Reservoir Report
Last Updated: March 4, 2026
Lake Thunderbird Lower Dam, also known as Thunderbird Lake Dam, is a private structure located in Callaway County, Missouri, specifically in the city of Portland.
Summary
Built in 1968 by designer Bill Crockett, this earth dam stands at 68 feet tall and stretches 400 feet in length. The dam serves primarily for recreational purposes, with a storage capacity of 612 acre-feet and a surface area of 20 acres.
Managed by the Dam and Reservoir Safety Program of Missouri, Lake Thunderbird Lower Dam is regulated, permitted, inspected, and enforced by the state. Despite being classified as having a low hazard potential, its condition was assessed as satisfactory as of November 2011. The dam features an uncontrolled spillway with a width of 65 feet and a maximum discharge capacity of 1056 cubic feet per second. With a moderate risk assessment rating, the dam is closely monitored to ensure the safety of the surrounding area and the Auxvasse Creek, which it regulates.
Water resource and climate enthusiasts interested in Lake Thunderbird Lower Dam will appreciate its unique design, purpose, and regulatory oversight. As a key component of the local recreation scene, this dam plays a vital role in water management and safety within the region. The collaboration between private ownership and state agencies ensures that the dam continues to function effectively while minimizing potential risks and hazards.
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15-Day Weather Outlook
Year Completed |
1968 |
Dam Length |
400 |
Dam Height |
68 |
River Or Stream |
TR-AUXVASSE CREEK |
Primary Dam Type |
Earth |
Surface Area |
20 |
Drainage Area |
916 |
Nid Storage |
612 |
Structural Height |
68 |
Outlet Gates |
None |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
68 |
Seasonal Comparison
5-Day Hourly Forecast Detail
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.
Lake Thunderbird Lower Dam