What is the test for discussing the cumulative impact of a project in an environmental review?

"An EIR must discuss a project's cumulative impacts 'when the project's incremental effect is cumulatively considerable, as defined in section 15065(a)(3).' (Guidelines, 15130, subd. (a).) ' "Cumulatively considerable" means that the incremental effects of an individual project are significant when viewed in connection with the effects of past projects, the effects of other current projects, and the effects of probable future projects.' [Citations.] 'A project's contribution is less than cumulatively considerable if the project is required to implement or fund its fair share of a mitigation measure or measures designed to alleviate the cumulative impact.' (Guidelines, 15130, subd. (a)(3).)" (Preserve Wild Santee v. City of Santee (2012) 210 Cal.App.4th 260, 276-277.)