What is the test for establishing a threshold of significance?

^9. A "threshold of significance" assists in determining the significance of a project's environmental impacts. (Mejia v. City of Los Angeles (2005) 130 Cal.App.4th 322, 342.) "Each public agency is encouraged to develop and publish thresholds of significance that the agency uses in the determination of the significance of environmental effects. A threshold of significance is an identifiable quantitative, qualitative or performance level of a particular environmental effect, non-compliance with which means the effect will normally be determined to be significant by the agency and compliance with which means the effect normally will be determined to be less than significant." (Guidelines, 15064.7, subd. (a).)