Terminal Reservoir Report

Last Updated: December 5, 2025

Terminal, also known as Lopez Reservoir, is a local government-owned dam located in Arroyo Grande, California.


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Summary

Completed in 1969, this earth-type dam stands at 53 feet in height and has a storage capacity of 844 acre-feet. Its primary purpose is water supply, serving the surrounding area with a maximum discharge capacity. The dam is regulated by the California Department of Water Resources and is inspected regularly to ensure its structural integrity and safety.

Situated on the Tr Arroyo Grande stream, Terminal dam plays a crucial role in managing water resources in San Luis Obispo County. With a hazard potential classified as high, the dam has undergone satisfactory condition assessments, last conducted in September 2017. Emergency action plans are in place, although the specifics of preparedness and risk management measures are not detailed in the available data. The dam's inspection frequency is set at 1 year, with the most recent inspection taking place in November 2020, showcasing a commitment to maintaining safety standards and compliance with regulatory agencies.

For water resource and climate enthusiasts, Terminal dam presents a fascinating case study of infrastructure designed to meet the water supply needs of a local community. Its strategic location, efficient design, and state-regulated operations highlight the importance of sustainable water management practices in the face of changing climate patterns and growing demands. As stakeholders continue to prioritize the safety and efficiency of water infrastructure like Terminal, this reservoir serves as a reminder of the critical role dams play in ensuring water security for communities in California and beyond.

Year Completed

1969

Dam Length

550

Dam Height

53

River Or Stream

Tr Arroyo Grande

Primary Dam Type

Earth

Surface Area

37

Hydraulic Height

47

Drainage Area

0.63

Nid Storage

844

Hazard Potential

High

Nid Height

53
       
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.