Valuing Wildlife Crossings and Enhancements for Mitigation Credits (2020)

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Valuing Wildlife Crossings and Enhancements for Mitigation Credits 40 5.0 CASE STUDIES 5.1.1 Background California’s Road Repair and Accountability Act of 2017 officially established the Caltrans Advance Mitigation Program to oversee the administration, planning, delivery, implementation, and tracking of Caltrans advance mitigation projects (Caltrans 2018). Codified in California Streets and Highway Code (SHC) 800 et. seq., advance mitigation projects eligible for funding consist of authorized activities pursuant to SHC §800.6(a), if Caltrans determines that the activity would provide appropriate compensatory mitigation of the anticipated potential impacts of planned transportation improvements. In general, the authorized activities pursuant to SHC §800.6(a), consist of (1) purchasing existing advance mitigation credits from conservation or mitigation banks or contributing to an HCP; or (2) establishing advance mitigation credits through existing regulatory processes and/or instruments (i.e., mitigation bank prospectus and instrument) (Caltrans pers. comm. 2019). Prior to the Advance Mitigation Program’s formal establishment, the Laurel Curve Wildlife Connectivity Project piloted Caltrans’ first advance mitigation project that established mitigation credits for constructing a wildlife crossing structure and fencing that may be applied to meet the compensatory mitigation needs of future transportation projects. The connectivity project was triggered by WVCs on a stretch of U.S. Highway 17 (Keeley et al. 2018). The Laurel Curve Project has been supported by research and data collected by a regional partnership among Caltrans, CDFW, county natural resource management agencies, land trusts, university researchers, and NGOs. Multiple species, especially mountain lions (Puma concolor) regularly use a corridor where Caltrans will install a wildlife crossing structure across the four-lane highway in the Santa Cruz Mountains, between the San Francisco Bay and Santa Cruz areas. Funding sources include, but are not limited to, Advance Mitigation Program funds from the 2016 State Highway Operation and Protection Program (SHOPP). Implementation of the crossing structure is slated for completion in 2020. The Laurel Curve wildlife crossing will enhance permeability across Highway 17, which was later identified as a conservation action for habitat connectivity in the Draft Santa Clara County RCIS (Santa Clara Valley Open Space Authority 2017). Before the RCIS program was established, Caltrans and CDFW signed a “pilot” credit agreement in 2017 for Caltrans’ financial contribution to the Laurel Curve Project (Caltrans and CDFW 2017). The Laurel Curve Project Credit Agreement established credits under the California Environmental Quality Act (CEQA) for a wildlife crossing structure and fencing that can be used to mitigate impacts of future transportation projects. The credit agreement allows Caltrans to apply wildlife crossing credits as compensation for the CEQA-significant impacts of transportation projects performed under the SHOPP within a specific service area. As CEQA-lead agency, Caltrans determines when credits may be applied to a transportation project. Funded through the SHOPP, the credits must be applied to SHOPP-funded transportation projects and may not be transferred or sold outside Caltrans (Caltrans pers. comm. 2019). Caltrans’ financial contribution to the Laurel Curve Project and its associated credit agreement, is one of the 12 projects funded through the 2016 SHOPP. 5.1.2 Mitigation Crediting The Laurel Curve Project Credit Agreement included a methodology reviewed by CDFW for establishing the credits associated with the installation of the new wildlife crossing (Caltrans and CDFW 2017). For this valuation of credits, Caltrans used a simple structural approach to calculate the total number of credits as 368, using the following explanation: “For the purposes of tracking and accounting, a credit was

Valuing Wildlife Crossings and Enhancements for Mitigation Credits 41 identified as being 0.1 acre.” The methodology to determine the number of credits generated was calculated as “the footprint of the highway reach” (36.8 acres) was divided into 0.1-acre credits, yielding 368 credits or 10 credits per acre (Caltrans and CDFW 2017). Valuing credits as equivalent to 0.1 acre was based on the fact that California mitigation banks often sell credits in this increment. This approach did not explicitly consider ecological conditions of the site, so the process does not directly measure the conservation gain from the project; however, the placement of the crossing is based on the research and data collected by the regional government, educational, research, and NGO partnership described above and hence is based on a putative increase in connectivity due to changing (increasing) the highway’s permeability. Credits established by the Laurel Curve Project will be debited as compensation for future transportation projects with significant impacts to wildlife under CEQA, as determined by Caltrans, the lead agency. The Caltrans and CDFW Credit Agreement specifies the types of potential impacts to which the project’s CEQA credits could be applied (debited) and provides notes about their use, presented in attachment B, table B-1 of the agreement, and provided in Table 3 (Caltrans and CDFW 2017). Although CEQA credits only require Caltrans’ internal approval to be applied to a transportation project, as a proof-of-concept, the credit agreement anticipates a future situation where, for example, ESA credits are issued, and agency permitting staff would have actual approval authority (Caltrans pers. comm. 2019). The agreement also defined the service area where eligible future transportation projects will be able to use the CEQA credits. U.S. Department of Agriculture, Forest Service ecoregional maps, other wildlife habitat data, and predictive models were used to define an appropriate service area. Table 3. Debiting guidelines for future transportation projects using credits generated from the Laurel Curve Wildlife Habitat Connectivity Project Type of Potential Impact to Wildlife Applicable Transportation Project Type Application of CEQA Credit(s) Notes SHOPP Repair and replacement of existing barriers without wildlife enhancements included Collision severity reduction, guardrail upgrades, upgrade median barriers Not applicable This is an example of maintaining a barrier and this scenario is not applicable to Caltrans projects funded through the SHOPP. When maintaining an existing barrier does not result in additional impacts above baseline conditions, it is not a significant impact under CEQA. Impacts from improvements of existing state highway system roads that that may decrease permeability of existing roads. Impacts of less Safety Improvements (e.g., curve corrections and re-alignments, lane or shoulder widenings); construction of guardrails Roadway Credits will be applied on a project-by-project basis. 10 credits per acre impacted OR 14 credits per lane mile impacted (see Attachment A for CEQA significance would be determined on a project-by- project basis. Avoidance and minimization measures are still required and determined on a project- by-project basis during

Valuing Wildlife Crossings and Enhancements for Mitigation Credits 42 Type of Potential Impact to Wildlife Applicable Transportation Project Type Application of CEQA Credit(s) Notes than 1 acre, such as permanent loss of roadside habitats during road construction. rehabilitation (e.g., road stabilization or shoulder rehabilitation), pavement preservation, pavement rehabilitation, drainage system restoration Major damage restoration (emergency opening) Major damage restoration (permanent restoration) Roadside safety improvements Slope stabilization conversion) transportation project planning and environmental review. When semi-permeable metal beam guardrail and three-beam median barriers are replaced with concrete, permeability may decrease. Caltrans may decrease permeability and discourage or redirect wildlife crossing due to adjacent land use(s) and/or road engineering constraints. Credits may be useful to local agencies where, based on a local entity's significance criteria, permeability has been unavoidably significantly impacted. State Transportation Improvement Program Impacts from improvements to state highway system roads that would increase traffic speeds or road capacity, resulting in greater danger to wildlife attempting to cross Construction of express lanes, lane additions, new interchange construction or interchange reconfiguration are examples of State Transportation Improvement Program projects. To be determined by separate future agreements CEQA significance would be determined on a project-by- project basis. Avoidance and minimization measures are still required and determined on a project- by-project basis during transportation project planning and environmental review. Impacts from new highways or major transportation features Construction of express lanes, lane additions, new interchange construction or interchange reconfiguration are examples of State Transportation Improvement Program projects. To be determined by separate future agreements CEQA significance would be determined on a project-by-project basis. Avoidance and minimization measures are still required and determined on a project- by-project basis during transportation project planning and environmental review. Source: Caltrans and CDFW (2017)

Valuing Wildlife Crossings and Enhancements for Mitigation Credits 43 Lastly, it is important to note that, regardless of whether advance mitigation is in place, Caltrans transportation projects will still proceed under standard environmental and permitting processes and must demonstrate avoidance and minimization of environmental impacts prior to considering the use of compensatory mitigation (Caltrans 2018). Caltrans would still consult with USFWS and CDFW about on- site effects to federal- and state-listed species and incorporate any recommended or required avoidance and minimization measures determined on a project-by-project during project planning and environmental review (Caltrans and CDFW 2017). In cases where adverse impacts to wildlife connectivity are unavoidable, on-site mitigation could still be performed. The types of Caltrans transportation projects that would likely purchase credits would be existing alignments that provide limited opportunity for avoidance and minimization (Caltrans pers. comm. 2019). In cases where adverse impacts on wildlife are unavoidable, on-site mitigation could still be performed. If a transportation project manager can find compensatory mitigation at a lower cost, Caltrans expects that they would choose that mitigation. Thus, for an individual transportation project to justify the expense of wildlife connectivity mitigation credits, the cost of any alternative compensatory mitigation credit/opportunity would need to be about the same or more. 5.1.3 Lessons Learned Under the Advance Mitigation Program framework, Caltrans demonstrated that it has been able to take ecosystem and landscape-level concerns into account (Sciara et al. 2015b), which bodes well for conserving wildlife connectivity via mitigation crediting. Advance mitigation has also been shown to reduce delivery times for projects in California by 1.3 to 5 months (Sciara et al. 2017). The Laurel Curve Project Credit Agreement describes how Caltrans may apply wildlife crossing credits as compensation for the CEQA-significant impacts of transportation projects performed under the SHOPP in a specific service area. As the CEQA-lead agency, Caltrans determines when credits may be applied to a transportation project. Funded through the SHOPP, the credits must be applied to SHOPP-funded transportation projects and may not be transferred or sold outside Caltrans. Caltrans believes that advance mitigation funds could be used for wildlife crossings if there were a crediting mechanism that (1) is acceptable by an agency with permitting authority; and (2) establishes credits where the credit cost is competitive with other mitigation source costs (Caltrans pers. comm. 2019). Strategies that facilitated the implementation of the Laurel Curve Project were the collection of extensive wildlife data from camera traps, collar data, roadkill, and linkage models (Caltrans pers. comm. 2019). A media campaign and land trust partners securing adjacent land were also important (Keeley et al. 2018). The approach taken by Caltrans to generate credits for the Laurel Curve Project did not directly measure the ecological improvement from the project. However, the project was a proof-of-concept effort to demonstrate the framework for developing credit agreements for wildlife crossing structures, and how credits generated from a wildlife crossing could be applied as mitigation for future transportation projects. Although other function-based or model-based metrics could have been used, a condition-based metric was straightforward, repeatable, and inexpensive to calculate. Caltrans practitioners acknowledged that other metrics could have been used that relate to the ecological gain from the project (Caltrans pers. comm. 2019). CDFW’s RCIS program is now in place and will enable future credit agreements to be developed in California for wildlife connectivity mitigation measures under the CEQA and other regulations under their authority, and future transportation projects can use the credits to satisfy compensatory mitigation requirements. CDFW (pers. comm. 2019) anticipates that future MCAs for wildlife crossing structures and other connectivity mitigation measures will consider other factors to quantify ecological gain, such as improved access to breeding sites or improved gene flow.

Valuing Wildlife Crossings and Enhancements for Mitigation Credits 44 5.2.1 Background The Florida panther, a subspecies of mountain lion, is a federally listed focal species for wildlife connectivity mitigation. Collisions with Florida panthers are not a high safety risk for drivers, but collisions with vehicles are a leading cause of Florida panther deaths. The prioritization of Florida panther connectivity mitigation has been driven by biological requirements of the subspecies rather than motorist safety. Data from GPS-collared Florida panthers showing travel corridors and panther-vehicle collisions have been the primary data source for identifying the locations of wildlife crossing structures (FDOT pers. comm. 2019). Smith et al. (1999) developed a decision-based GIS model for FDOT road improvement projects associated with road mortality of wildlife and other environmental impacts that is integrated to other state environmental initiatives and programs for conservation and recreation land protection. This decision-based priority model has enabled FDOT, in coordination with USFWS, to identify potential wildlife crossing projects according to the conservation needs of Florida panthers, 5.2.2 Mitigation Crediting USFWS provided guidelines to FDOT for determining the appropriateness of including wildlife crossings (upland or wetland) and/or exclusionary devices (fencing, walls, temporary barriers, etc.) on proposed FDOT projects or on existing highways as retrofits (USFWS 2015). These guidelines recommend that “wildlife crossings and/or exclusionary devices should only be considered when the project is a capacity improvement that involves the addition of travel lanes.” FDOT previously explored the idea of implementing wildlife crossings or retrofits to existing structures as mitigation measures for Florida panthers. However, although three conservation banks have been finalized within the Florida panther’s breeding range and connectivity across highways is a primary focus for the species’ conservation, USFWS does not allow wildlife crossings to qualify for compensatory mitigation for panther habitat loss. Although wildlife crossings reduce the likelihood that panthers will be struck by vehicles, they do not compensate for habitat lost due to a road project (FDOT pers. comm. 2019). Thus, where appropriate, USFWS requires wildlife crossings for transportation projects that adversely affect the Florida panther and habitat mitigation credit purchases to offset the loss of habitat. Because some development projects do not cause substantial habitat loss for Florida panther but do generate increased traffic that contributes to panther mortality, USFWS considers increases in traffic an indirect effect from a project (USFWS 2012b). Although USFWS does not provide a mechanism to generate mitigation credits from wildlife crossings, the USFWS (2012b) Panther Habitat Assessment Methodology provides a method for calculating mitigation credit requirements for development projects that would indirectly affect panthers via increased traffic. For projects that would increase traffic and reduce highway permeability, the number of mitigation credits are calculated by converting the average cost of a wildlife crossing structure to the equivalent acreage of land that could be purchased for that amount. This methodology is intended to incentivize the construction of wildlife crossings by assessing mitigation credit requirements as follows: we are providing a habitat surrogate of 500 acres per year of habitat loss for these types of projects, with a not to exceed value of 2,500 acres over the 5-year period. The 500 acres per year is based on average cost of FDOT bridge/box culvert crossings (3.6 to 5 million dollars) converted to acreage equivalent costs ($8,500/acre). This 2,500-acre habitat surrogate adds an additional 28 acres per panther to the above adjusted base for a new base of 32,951 acre per panther (2,500 [acres] / 90 [panthers] = 28 +288+352+31,923=32,591). Therefore, [USFWS] has added another 0.02 to the base

Valuing Wildlife Crossings and Enhancements for Mitigation Credits 45 ratio to address traffic impacts, which could provide an incentive to implement crossings in key locations. 5.2.3 Lessons Learned The method used by USFWS in south Florida to assess mitigation credit requirements due to increased traffic is informative about current efforts to monetize the indirect impacts of transportation projects on a focal species. The approach is unique in that it uses the average cost of a wildlife crossing structure as the reference value (price) for quantifying the acreage equivalent of habitat. Under a crediting system for wildlife connectivity mitigation, the impacts on wildlife from future increases in traffic could be estimated with a similar approach and mitigation credits generated from wildlife crossings or other connectivity enhancements could be applied to compensate for the impacts. 5.3.1 Background State Road 40 (SR 40) bisects large areas of undeveloped natural habitat in central Florida that provide wildlife movement corridors in an increasingly fragmented region. Much of the adjacent land is public, including the Ocala National Forest, Silver River State Park, Heart Island Conservation Area, and Marjorie Harris Carr Cross Florida Greenway State Recreation and Conservation Area. These lands are important to several threatened and endangered or special-status species, including the Florida scrub-jay, red-cockaded woodpecker, eastern indigo snake, sand skink, and Florida black bear. To address wildlife connectivity, FDOT took an innovative approach to incorporate the ecological benefits of enhancing wildlife connectivity at existing drainage structures and dedicated upland wildlife crossings into calculations of project wetland mitigation requirements. FDOT collaborated with several key stakeholders to evaluate whether improvements to SR 40 would be feasible given the nature and complexity of the wildlife concerns. The result was a memorandum of agreement between FDOT, USFWS, Florida Fish and Wildlife Conservation Commission, and FDEP, referred to as the SR 40 Task Force. A Wildlife Crossing Committee (WCC) was established that included biologists, planners, and wildlife advocates. As the project moved from the NEPA phase into design, the WCC met regularly (Lyon and Houck 2018). The design phase included breaking the NEPA study into four separate design projects, two in Marion County and two in Volusia County. To address wildlife connectivity mitigation for the SR 40 project, FDOT applied the scoring system of FDEP’s UMAM to calculate mitigation credits in terms of the functional gain provided by wildlife crossing structures. Functional gain is the term used to identify the UMAM score a project’s overall ecological benefit in the post‐construction condition attained and is typically used for wetland mitigation credits requirements and evaluating restoration sites (Lyon and Houck 2018). The UMAM was not specifically used to score wildlife crossings previously, so FDOT had to develop a method for consistently applying it for the SR 40 project. 5.3.2 Mitigation Crediting Wildlife crossing structures (culverts and bridges) were sited specifically to connect existing conservation lands where they abutted the SR 40 corridor. For each proposed crossing structure, an assessment area, or the potentially impacted geographic area, was defined based on the home range or dispersal distances of aquatic or wetland-dependent focal species. The UMAM was then used to determine the mitigation needed to compensate for adverse impacts on wetlands and other surface waters by assessing their ecological functions according to three categories. One category of wetland function, Location and Landscape Support, evaluates an area’s value as a corridor for wildlife movement. As defined in Florida Administrative Code, Chapter 62-345,

Valuing Wildlife Crossings and Enhancements for Mitigation Credits 46 The location of the assessment area shall be considered to the extent that fish and wildlife utilizing the area have the opportunity to access other habitats necessary to fulfill their life history requirements. The availability, connectivity, and quality of offsite habitats, and offsite land uses which might adversely impact fish and wildlife utilizing these habitats, are factors to be considered in assessing the location of the assessment area. The Location and Landscape Support category is intended to specifically address the pre‐ and post‐ construction connectivity for wildlife to and from habitats outside the project area. Two of eight attributes for quantifying an area’s Location and Landscape Support measure wildlife connectivity, which is scored numerically on a scale from 0 to 10, as not present (0), minimal (4), moderate (7), or optimal (10). These two attributes are: (1) the extent to which “habitats outside the assessment area represent the full range of habitats needed to fulfill the life history requirements of all wildlife” … and the extent to which these habitats “are available in sufficient quantity to provide optimal support for wildlife;” and (2) the extent to which “functions of the assessment area that benefit downstream fish and wildlife downstream are not limited by distance or barriers that reduce the opportunity for the assessment area to provide these benefits.” (Florida Administrative Code 62-345) The UMAM scores calculated an increase to the Location and Landscape Support score by 1 point, which translated to a 10% increase in habitat quality due to the inclusion of the wildlife crossings. The number of mitigation credits generated for each wildlife crossing structure, the relative functional gain, was calculated for each assessment area, and adjusted for two additional factors, time lag and risk. Time lag accounts for the time at which the ecological functions are lost due to an impact (e.g., construction) and when the project has achieved the outcome of increased wildlife permeability. A time lag factor was used for wildlife crossing structures that did not include exclusionary fencing to funnel wildlife towards the structure, based on the assumption that, due to the lack of fencing, it would take 3 years to achieve increased wildlife permeability. A risk factor was also incorporated into the calculations for the crossing structures to account for the degree of uncertainty that wildlife would use the structures. This methodology was used for one of the Volusia County design sections of SR 40. USACE issued a permit for the project in October 2017, which included the following conditions specific to the wildlife crossings: (1) FDOT shall maintain the crossings and fencing areas as initially permitted in perpetuity; (2) post-construction photos are to be collected by wildlife cameras mounted on the crossing structures and will be included in an annual monitoring report; (3) FDOT will perform a monitoring event within 60 days and provide a report to USACE; and (4) FDOT will perform annual monitoring for no less than 2 years and submit a report to USACE within 60 days of the monitoring completion (Lyon and Houck 2018). On the Marion County sections of SR 40 that cross through the Ocala National Forest and Silver River State Park, based on the same NEPA study, the WCC identified the need for up to 26 additional wildlife crossing structures. However, the same method as described above could not be applied because the proximity of the crossing structures, if assessed the same way, would double or triple count the assessment area of each crossing structure and result in an artificially high relative functional gain. The solution was to overlap the assessment areas into enhancement zones and calculate the UMAM scores accordingly, as multiple wildlife crossing structures would work together to provide wildlife connectivity. The result is one UMAM score for each enhancement zone. This project is currently under review with USACE (Lyon and Houck 2018).

Valuing Wildlife Crossings and Enhancements for Mitigation Credits 47 Similar to the SR-40 projects, FDOT also plans to use a proposed wildlife crossing of I-4 as partial mitigation for proposed impacts to waters of the United States (Stantec Consulting Services, Inc. 2019). UMAM was used to quantify the total number of mitigation credits generated from a proposed wildlife crossing structure to demonstrate the benefits to rare species like the Florida panther and black bear. The primary goal of the wildlife crossing will be to restore an important landscape connection for wildlife that was severed by the original construction of I-4 in the early 1960s. Because of the significance of the I-4 habitat fragmentation effect and the potential benefits of a wildlife crossing to upland and wetland species based on the UMAM results, Florida Fish and Wildlife Conservation Commission supported the concept of allocating wetland mitigation credits for this project (Stantec Consulting Services, Inc. 2019). 5.3.3 Lessons Learned The SR 40 project demonstrates that using an existing wetland assessment methodology to calculate mitigation credits can effectively reduce overall mitigation requirements of a large transportation project by valuing the functional gain provided by wildlife crossings or enhancement of drainage structures for safe wildlife passage. Because most transportation projects include culverts and bridges across natural features, there are typically cost-effective opportunities to enhance wildlife connectivity via retrofitting culverts or modifying bridges to better serve focal species. Providing an option to generate mitigation credits for enhancing existing drainage structure would provide state DOTs with a great incentive to mitigate impacts by pursuing proven wildlife connectivity mitigation in locations where many species naturally cross over or under highways. In such situations, the use of UMAM demonstrates that there are existing wetland mitigation assessment methodologies that include useful metrics to value wildlife connectivity mitigation. UMAM is not the only wetland mitigation assessment methodology that considered wildlife connectivity. In its Ecological Performance Standards for Wetland Mitigation, NatureServe (Faber-Langendoen et al. 2008) includes a “Landscape Context” metric as a categorical performance standard for wetlands mitigation, which measures “the percent of unfragmented landscape within 1 km area (non-riverine), or degree to which the riverine corridor above and below a floodplain area exhibits connectivity with adjacent natural systems (riverine).” A simple metric such as this could be incorporated into calculations of a transportation project’s mitigation requirements for the benefit of species that use wetlands and watercourses as movement corridors between large blocks of intact habitat. Also, the formation of an interagency working group focused on wildlife crossings was effective at overcoming many years of disagreement and led to a collaborative solution to incorporate in-kind wildlife connectivity mitigation. The effort exemplifies the first step of an ecosystem approach to developing transportation projects, to “build and strengthen collaborative partnerships” (Brown 2006). 5.4.1 Background Colorado has increasing highway traffic and relatively high WVCs, so CDOT is working diligently to address wildlife connectivity. Colorado does not have any wildlife connectivity mitigation projects that have used a mitigation crediting framework; however, CDOT’s experience with advance mitigation and its planning for wildlife connectivity is a good example of interagency cooperation to develop a consistent strategy for measuring both the relative ecological impacts of transportation projects and the restoration benefits of wildlife crossings and other connectivity enhancements. CDOT has been identifying WVC hotspots and linkage areas for more than two decades (Barnum 2003, Crooks et al. 2008, Southern Rockies Ecosystem Project 2005). The results of the ALIVE analysis were incorporated into long-term commitments along the I-70 corridor. CDOT recently performed the West

Valuing Wildlife Crossings and Enhancements for Mitigation Credits 48 Slope Wildlife Prioritization Study, a regional prioritization of highway segments for wildlife connectivity mitigation across the mountainous western one-third of Colorado, where wildlife connectivity issues are greatest (Kintsch et al. 2019). Due to the potential integration of this effort into CDOT project planning, budgeting, and design, CDOT is performing a similar prioritization of wildlife crossing locations in eastern Colorado (CDOT pers. comm. 2019). The West Slope Wildlife Prioritization Study is a multi-agency comprehensive approach to valuing future high-priority wildlife connectivity mitigation projects. Note that CDOT practitioners stressed that the agency mission is focused on motorist safety (CDOT pers. comm. 2019), so WVCs were the primary metric of concern, in combination with migration and habitat data for mule deer and elk. The main objective for CDOT was to identify wildlife-highway conflict areas under both current conditions and future land use and traffic scenarios to identify where mitigation could have the greatest impact on reducing WVCs. The West Slope Prioritization Study produced the following products: (1) a prioritized list and maps of highway segments with wildlife-highway conflicts; (2) milepost-specific recommendations for potential wildlife crossings; (3) a benefit-cost analysis for the highest priority segments; and (4) a decision-support toolbox that includes best practices for integrating prioritized wildlife-highway segments into transportation planning and project development, or, in select cases, identifying potential stand-alone mitigation projects. 5.4.2 Mitigation Crediting This project did not use mitigation credits to value wildlife crossings or other connectivity enhancements. However, the function-based and avoided cost metrics used for prioritizing wildlife connectivity on a regional basis are among the most useful metrics that state DOTs could use to quantify credits under a mitigation program for wildlife connectivity. The data available for analysis included current and predicted traffic volumes; 10 years of reported WVC accident report data; 10 years of WVC carcass data; GPS collar data from 10 studies of mule deer and five studies of elk; and seasonal habitat and migratory corridor mapping. The GPS collar data were used to develop models predicting the probability of mule deer and elk crossing highways but were not used to prioritize wildlife crossings because the models poorly predicted mule deer and elk habitat selection along highways. Alternatively, WVC risk was modeled for both mule deer and elk based on observed WVCs crash and carcass data (Kintsch et al. 2019). Kintsch et al. (2019) also explored several additional prioritization criteria, which could foreseeably be used as metrics to value wildlife crossings or other connectivity enhancements focused on mitigating impacts from deer and elk collisions. These include the density of mule deer and elk herds in winter concentration areas along highways; the distance of mule deer and elk migration movements multiplied by herd sizes; the 5-year average annual WVC count as a proportion of mule deer and elk herd sizes; and the modeled connectivity value for other potential focal species, such as Canada lynx. 5.4.3 Lessons Learned The West Slope Wildlife Prioritization Study is a good example of a state DOT completing step 5 of the IEF as it would relate to wildlife connectivity. The study demonstrates that the prioritization of wildlife connectivity mitigation is useful for identifying potential metrics that are informative for valuing wildlife crossings and other enhancements in the western United States. The study revealed that GPS collar data from studies of mule deer and elk in proximity to highways, but not focused on highway impacts, may not be predictive of their highway crossings. WVCs and accident report data were most informative for prioritizing mitigation and would be among the most useful metrics. Furthermore, the cost-benefit model identified locations where wildlife connectivity mitigation could generate the most value if the credits were to be based on the model results or its input parameters.