Rendering of the wildlife overpass above I-25
In Douglas County, wildlife crossings are a key part of regional efforts to balance public safety, transportation needs and long-term wildlife conservation. Douglas County and its partners, including Colorado Parks and Wildlife (CPW), Colorado Department of Transportation (CDOT), and the Federal Highway Administration, have been working together since 1996 to safeguard wildlife habitat and strategically engineer wildlife crossing structures along 18 miles of I-25 between Castle Rock and Monument (known as the Gap).
This multi-decades-long process includes the new, history-making Greenland Wildlife Overpass under construction just north of the El Paso County/Douglas County line. Once completed, it will be one of the largest wildlife overpasses in the world, spanning six lanes of Interstate traffic, connecting 39,000 acres of habitat on both sides of I-25 and completing a vital safe-crossing network for wildlife, including elk, deer, antelope (pronghorn), bear, mountain lion, coyote and at least a dozen other species of mammal.
The overpass will complete the 18-mile-long system of underpasses and fencing, essentially preserving one of the only remaining regional corridors connecting the mountains to the Eastern Plains for many species.
A wildlife crossing is a structure designed to allow animals to safely cross human-made barriers such as roads, highways or railways. These crossings help prevent wildlife-vehicle collisions, reduce injury to motorists and maintain habitat connectivity for native species. There are two main types of wildlife crossings:
Underpasses: tunnels, culverts or large openings that pass beneath roadways
Overpasses: vegetated bridges built over roads that mimic natural terrain
Wildlife crossings are often paired with wildlife exclusionary fencing, which guides animals toward the crossing and keeps them off the road. These structures are customized based on the local landscape and species.
Between Castle Rock and Monument, I-25 bisects 55 square miles of protected land. This is the largest contiguous preserved habitat on the Front Range. This area of southern Douglas County is home to large elk and deer herds, among dozens of other migrating animal species which rely upon safe passage to the east and west sides of I-25 for critical access to food, water and shelter.
Before the construction of 5 underpasses and the Greenland overpass, at least one deer or elk was hit on I-25 every day in the summer and early fall. Between 2011 and 2015, vehicle-wildlife collisions accounted for 785 crashes, or 6% of crashes each year.
This slide is from the Douglas County Wildlife Planning & Corridor System presentation linked in the section below.
Douglas County has worked closely with local, state and federal partners since 1996 to identify long-term solutions that support both safe, efficient Front Range transportation and the preservation of wildlife habitat and movement corridors. The agreed-upon approach was to establish a series of functional wildlife crossings along the I-25 corridor.
Crossing locations were selected based on a combination of data: typography, areas with high wildlife-vehicle collision rates, known movement paths and the presence of large, contiguous habitat areas on both sides of the roadway. Studies and recommendations from CDOT, CPW and the I-25 Planning and Environmental Linkages (PEL) Study helped guide these decisions.
This page is from the I-25 PEL Executive Summary linked in the section below.
This page is from the I-25 PEL Executive Summary linked in the section below.
This map of wildlife crossings is from the Douglas County Wildlife Planning & Corridor System presentation linked below.
Douglas County and its partners have invested over $300 million in habitat conservation and wildlife connectivity projects over the last 30 years. Funds have been used toward planning, research, easements, construction and investing in open spaces.
Funding has come from a combination of sources, including Douglas County’s voter-approved Parks, Trails, Historic Resources and Open Space sales tax, state and federal grants, private land purchases under conservation easement and partnerships with municipalities and conservation organizations.
Yes! 2023 and prior data show there have been nearly 5,300 instances of mule deer using the wildlife corridor underpasses to safely cross I-25. The Monument Hill and Greenland underpasses are the most heavily used by deer.
This page is from the I-25 Wildlife Mitigation Data document linked in the section below.
This page is from the I-25 Wildlife Mitigation Data document linked in the section below.
As Douglas County grows, it’s critical to balance development with the conservation of natural resources. Section 9 of the County’s Comprehensive Master Plan includes policies to protect wildlife habitat and ensure that infrastructure projects are planned with conservation in mind.
