FL S1646

Defines "proximity factor" as a new term in Florida law, meaning the variable measurement used to determine the amount of wetland mitigation credits required based on a project site's location relative to the wetland mitigation bank and its significance within the basin

Requires the Department of Environmental Protection and water management districts to allow the use of mitigation credits from surrounding basins when credits are unavailable in a project area basin, with unavailability demonstrated by a signed letter from the mitigation bank in that basin

Establishes a tiered proximity factor system for out-of-basin credits: up to 1.5 credits for projects within a contiguous basin, up to 2 credits for projects within the watershed but not contiguous, and an additional 0.25 credits for each additional basin beyond the project site

Adds a new category of projects eligible to use mitigation banks outside their mitigation service area: projects approved on a case-by-case basis when sufficient credits are not available to offset imminent and otherwise allowable adverse impacts within the service area

Requires the Department of Environmental Protection to publish proposed rules implementing the new provisions by September 1, 2024, and specifies that the use of out-of-basin mitigation credits may not affect U.S. Army Corps of Engineers credits