Tmpa Gibbons Creek Mine Dam Sp-1 Reservoir Report

Last Updated: December 5, 2025

Tmpa Gibbons Creek Mine Dam Sp-1, located in Grimes, Texas, is a local government-owned structure designed by Morrison Knudson.


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Summary

This earth dam, standing at a height of 25 feet, was completed in 1987 and serves a primary purpose that is classified as 'Other'. The dam has a storage capacity of 1095 acre-feet, with a normal storage level of 440 acre-feet and a surface area of 87.5 acres.

The dam, situated on Rock Lake Creek, is regulated by the Texas Commission on Environmental Quality (TCEQ) and undergoes state permitting, inspection, and enforcement. With a spillway type classified as 'Uncontrolled' and two uncontrolled outlet gates, the dam has a moderate risk assessment rating. Despite not having a hazard potential or condition assessment rating available, the structure is considered to have a moderate risk level (3) associated with it.

Overall, Tmpa Gibbons Creek Mine Dam Sp-1 presents an intriguing case study for water resource and climate enthusiasts due to its unique design elements, regulatory oversight, and risk assessment profile. The dam's historical significance, operational details, and environmental impact make it a noteworthy subject for further research and analysis in the field of water resource management and climate resilience.

Year Completed

1987

Dam Length

4750

Dam Height

25

River Or Stream

ROCK LAKE CREEK

Primary Dam Type

Earth

Surface Area

87.5

Hydraulic Height

25

Drainage Area

0.17

Nid Storage

1095

Structural Height

25

Outlet Gates

Uncontrolled - 2

Hazard Potential

Not Available

Foundations

Unlisted/Unknown

Nid Height

25
       
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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.