In Lotus v. Department of Transportation (2014) 223 Cal.App.4th 645, the court held that an EIR prepared by Caltrans did not comply with CEQA because it failed to evaluate the significance of a project's impact on the root systems of old growth redwood trees adjacent to a planned roadway. (Lotus, supra, 223 Cal.App.4th at p. 653.) The court noted that the EIR disclosed that the project activity would "take place within the root zones of specific old growth redwood trees" and would also result in changes to the "impermeable area covering the root zones of some of the old growth redwood trees." (Id. at p. 654.) The EIR did not, however, "include any information that enables the reader to evaluate the significance of these impacts." (Ibid.) The appellants in that case argued that the proper measure of significance was found in a publication by another agency, namely the State Parks Natural Resources Handbook. (Ibid.) This handbook contained various standards for determining the probability that a given tree would be damaged by construction on or around its root system. (Ibid.) Caltrans "implicitly acknowledged the value of the handbook" by referring to its standards in its appellate brief. (Ibid.) Nonetheless, the "EIR itself . . . did not reference the handbook or apply the standards it prescribes to evaluate impacts to the old growth redwoods that may be expected to result from the highway construction." (Id. at p. 655.) The error by Caltrans in Lotus, however, was not its failure to apply the significance standards in the State Parks' Handbook in the EIR. Rather, the agency erred by failing to adopt any standard for determining whether the planned project would have significant effects on old growth redwood trees: "The EIR fails to identify any standard of significance, much less to apply one to an analysis of predictable impacts from the project." (Lotus, supra, 223 Cal.App.4th at p. 655.) While the court discussed the State Park Natural Resources Handbook standards at length because the parties were in apparent agreement that they were relevant, the court did not hold that Caltrans had been required to apply those standards. Rather, the court stated: "We do not suggest that the handbook is the only or necessarily the best measure for determining significance. The standard of significance applicable in any instance is a matter of discretion exercised by the public agency 'depending on the nature of the area affected.'" (Id. at p. 655, fn. 7.)