The Willow Creek Falls trail has been decommissioned by Colorado Parks and Wildlife between its junction with Douglas County Road 5 (listed on OSM as Iron Bark Drive) and its junction with the Bear Canyon Trail. Access is now via the the Bear Canyon Trail, which now extends farther than is shown on this map. I have information from Tim Mastic
Visitor Services Manager & Volunteer Coordinator Roxborough State Park that this segment of trail should be removed. "Willow Falls Trail is no longer a legal trail and has been decommissioned. I give you authorization if you'd like to submit the requests!"