Pub. Resources Code, § 29114

(a) “Development” means on land, or in or under water, the placement or erection of any solid material or structure; discharge or disposal of any dredged material or of any gaseous, liquid, solid, or thermal waste; grading, removing, dredging, mining, or extraction of any materials; change in the density or intensity of use of land, including, but not limited to, subdivision pursuant to Subdivision Map Act (commencing with Section 66410 of the Government Code), and any other division of land including lot splits, except where the land division is brought about in connection with the purchase of such land by a public agency for public recreational use; change in the intensity of use of water or in access thereto; construction, reconstruction, demolition, or alteration of the size of any structure, including any facility of any private, public, or municipal utility; and the removal or harvesting of major vegetation other than for agricultural purposes.

(b) “Development” does not include either a change in the intensity of use of water or the removal or harvesting of major vegetation where such change, removal, or harvesting is to maintain or improve wildfowl habitat and does not have a significant, adverse effect on other fish and wildlife resources in the marsh.