The mitigation rule does not establish minimum ratios for mitigation proposals, but does establish that, for preliminary planning purposes only, ratios typically are 2 acres created : I acre affected. The ultimate ratios that are accepted are adjusted up or down, based on:
- Time to restore wetland functions
- Special classifications of waterbody (OFWS)
- Type of wetland to be created
- Condition and value of functions being performed by the impacted area compared to the character and quality of wetlands to be created
- Uniqueness of the impacted wetlands
- Presence of exotic or nuisance species in the impacted wetlands
- Whether the project eliminates wetlands or changes wetlands from one type to another
Based on past permitting histories, the following ranges of ratios are assigned to mitigation proposals:
- Restoration and creation ratios:
- Mangrove swamps, cypress swamps, and hardwood swamps: 2:1 to 5:1
- Saltwater and freshwater marshes: 1.5:1 to 4:1
- Enhancement ratios: 4:1 to 20:1, based on criteria in Section 62-312.340(3), F.A.C., including the degree, type, and cause of stress, whether the enhancement method is low maintenance or self regulating. and the likelihood of success in offsetting adverse impacts.
- Preservation ratios: 10: 1 to 60: 1
The lowest end of the ratio range is most appropriate when a high degree of reasonable assurance exists hat the mitigation will be successful and capable of offsetting the otherwise unpermittable aspects of the project, which can best be achieved through preconstruction mitigation efforts.