San Carlos v. State/resolution

Summary

The court held that Shaft 10 is not a "new source" under the Clean Water Act and that ADEQ acted within its discretion in renewing Resolution's discharge permit. It established a sequential three-step framework requiring courts to evaluate the regulatory definition of new source, the criteria concerning the construction's relationship to existing sources, and whether an independently applicable new source performance standard exists. Applying that framework, the court found Shaft 10 integrated with the existing mine, engaged in the same general type of activity, and lacking an independently applicable performance standard.