Islands tend to be more complex than mainland because of the...

Islands tend to be more complex than mainland because of the geographic isolation. This means that you tend to get either: (a) species that are endemic to the island and not found on the mainland; or (b) different genetic diversity of otherwise common species that are confined to the island and making them important in their own right. For reasons like these, I'd say that an EIS for Irvine is likely to be a little more complicated than for a similar sized operation on the mainland.