Mary Rhodes Phase 2 Sedimentation Basin Dam Reservoir Report

Last Updated: December 5, 2025

The Mary Rhodes Phase 2 Sedimentation Basin Dam, located in Matagorda, Texas, is a crucial structure managed by the local government to regulate the off-channel Colorado River.


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Summary

Designed with a stone core and a soil foundation, this dam stands at a height of 13 feet and has a length of 3300 feet. It serves as a key component in maintaining water resources and climate control in the region.

With a storage capacity of 131 acre-feet and a normal storage of 74 acre-feet, this dam plays a vital role in flood control and water management. The uncontrolled spillway with a width of 40 feet ensures effective discharge during high water levels. The dam's satisfactory condition assessment and moderate risk rating highlight its importance in providing essential services to the surrounding area.

Managed by the Texas Commission on Environmental Quality (TCEQ), the Mary Rhodes Phase 2 Sedimentation Basin Dam is subject to state regulation, inspection, and enforcement. Its role in maintaining water resources and mitigating climate-related risks underscores the significance of this structure in safeguarding the local community and environment.

Dam Length

3300

Dam Height

13

River Or Stream

OFF CHANNEL COLORADO RIVER

Primary Dam Type

Other

Surface Area

12

Hydraulic Height

13

Drainage Area

0.02

Nid Storage

131

Structural Height

13

Outlet Gates

Uncontrolled - 1

Hazard Potential

Not Available

Foundations

Soil

Nid Height

13
       
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.