In the context of irrigation systems, when measuring setbacks, which feature's elevation is used?

In the context of irrigation systems, when measuring setbacks, it is crucial to use the normal pool elevation. This reference point is vital because it represents the typical water level of a body of water, such as a pond or lake, during its normal operating conditions. Understanding the normal pool elevation helps in determining the proper distance that irrigation systems should be set back from bodies of water to prevent potential contamination and ensure compliance with regulations.

By relying on the normal pool elevation, installers can establish safer distances that consider variations in water level due to climatic conditions, seasonal changes, and water management practices. This practice helps mitigate risks associated with water overflow or runoff that could affect the surrounding environment and maintain the integrity of both the irrigation system and the natural water body.

Other options would not provide the necessary accuracy or safety margin. For instance, ground level could change due to erosion or other factors, while average high tide would only be relevant for coastal areas and not suitable for inland environments. The lowest point of the land might also vary significantly across a landscape and does not reflect the water body's actual behavior. Thus, relying on normal pool elevation is the most reliable and standardized approach for measuring setbacks in relation to irrigation systems.