What is “adequate mitigation”?
Both CEQA and NEPA require historic properties to be protected to the greatest extent feasible. Assessing impacts is an iterative process that first examines the significance of the resource, its boundaries and character defining features, and then evaluates a project’s effects upon those characteristics. Impacts can be direct, indirect or cumulative. Direct impacts physically change character defining features and noticeably diminish the resource’s significance. Indirect impacts like noise, light and glare, do not physically alter the resource, but diminish its character. Cumulative impacts may not be individually significant, but collectively add up to great loss. After determining the type and extent of impact, determine how to avoid, minimize or mitigate the loss. Adequate mitigation lowers the impact to a “less than significant” level.