In an opinion filed on December 29, 2020, the First Appellate District in Santa Clara Valley Water District v. San Francisco Bay Regional Water Quality Control Board upheld a Responsible Agency’s imposition of additional mitigation more than a year after it had issued an initial approval for the project. Although the court was careful to say that it was addressing “unique circumstances” that would “seldom arise,” the decision is potentially problematic for project proponents, and especially for public agencies trying to pursue necessary public-infrastructure projects.