Taking the long road: A 10-year approach for valuing and evaluating wildlife crossings for compensatory mitigation on Florida’s roadways

Florida is the third most populous state in the U.S. at 22 million, adding 1,000 new residents daily. The vast majority of the state’s population growth occurs in central and south Florida, where large urban centers and roads have displaced and fragmented habitat for many wildlife species, including the Florida black bear and federally endangered Florida panther. Roads can also cause wildlife-vehicle collisions (WVC), resulting in injury and death to animals and motorists and reducing genetic exchange between wildlife populations.
The Florida Department of Transportation (FDOT) has collaborated with permit and wildlife agencies, non-governmental organizations, and research universities to address road effects on wildlife and people. Wildlife crossings are a successful and often-recommended mitigation strategy for reducing WVC and improving road permeability. However, wildlife crossings are expensive. For example, the cost for a single wildlife crossing at I-4 and SR 557 in central Florida will exceed $10 million and may not be cost-feasible for other roadways.
In order to control the costs of wildlife crossings, some FDOT districts have had to think outside the box. The Clean Water Act and state rules require compensatory mitigation for unavoidable impacts on aquatic resources. Private mitigation banks offer “credits” for compensatory mitigation, but those credits are expensive and may not provide localized mitigation. Certain banks are more than 70 miles from the project. Instead, FDOT has used the state’s Uniform Mitigation Assessment Method (UMAM) to calculate the improved functional values and compensatory mitigation from new wildlife crossings. We first proposed this strategy at the 2013 ICOET.
UMAM evaluates habitat functions based on four parameters: 1) location and landscape support, 2) water environment, 3) community structure, and 4) assessment area. FDOT calculated current and post-construction UMAM scores for two wildlife crossing projects in central Florida: I-4 at SR 557 and SR 40. We focused on the size of the assessment areas (i.e., where we expect to see the greatest wildlife benefits), which dramatically affect mitigation values. Our analyses support the position that wildlife crossings improve habitat values and can provide compensatory mitigation. Our analyses and permits reduced the compensatory mitigation for each project by 25%, at a cost savings of more than $2 million.
Currently, FDOT has prepared a state-wide UMAM concept for wildlife crossing projects in coordination with our Central Office and permit and wildlife agencies. The concept includes considerations for 1) traffic volumes, 2) poorly connected habitats, 3) critical habitats, 4) data gaps, and 5) crossing design. The concept also addresses the Florida panthers, which have a private mitigation bank industry focusing on land preservation rather than wildlife crossings. Our concept intends to incentivize new wildlife crossings through mitigation savings.