California Code, Fish and Game Code - FGC § 1790

Upon the successful creation of any wetlands of at least 20 acres, or in the case of vernal pools, upon successful creation of vernal pools on a site at least 20 acres in size, the operator may request a determination by the department of the number of acres in the mitigation bank site, and the relative habitat value thereof, that qualify for credit against prospective wetland loss in the qualifying urban area. In determining the amount of mitigation bank credit, no credit shall be provided for habitat values or acreage that was in existence prior to the establishment of the bank.