When using CEQA to challenge a land use decision a party must inform the public agency of an alleged CEQA violation before filing an action in court. (Pub. Res. Code, § 21177(a)(b); Don't Cell Our Parks v. City of San Diego(2018) 21 Cal.App.5th 338, 358.). Failure to exhaust your administrative remedies by voicing your concerns and appealing the environmental decision will preclude you from being able to litigate the matter. This exhausting doctrine even applies in San Diego with its bifurcated appeal process. So make sure to appeal not only the land use decision but also the environmental decision which is often two separate actions.
Next, if you choose to litigate a CEQA case, it is important to raise all the claims in the initial lawsuit since res judicata bars those issues that were litigated or could have been litigated. Citizens for Open Government v. City of Lodi (2012) 205 Cal.App.4th 296, 324. This rule can apply even when a City or County vacates the certification of an EIR and project approval based on court order and later certifies the EIR. Ione Valley Land, Air, and Water Defense Alliance, LLC v. County of Amador (Feb. 26, 2019, No. C081893) ___Cal.App.5th___ [2019 Cal. App. LEXIS 230], certified for partial publication March 20, 2019)