Heil Valley Ranch Cal-Wood Fire Recovery
Cal-Wood Fire at Heil Valley Ranch

Heil Valley Ranch Cal-Wood Fire Recovery

Recovery work is underway at Heil Valley Ranch from the devastating Cal-Wood Fire. Recovery operations include hazard tree removal, aerial mulching, erosion mitigation, and replacing damaged visitor amenities and park infrastructure including bridges, fencing, parking stops, and signs.

Cal-Wood Fire

The Cal-Wood Fire started on Oct. 17, 2020, and raced downwind and downslope through Heil Valley Ranch. It consumed 5,000 acres in about five hours. In the end, it covered over 10,000 acres with more than half of that on Boulder County owned property (4,400 acres) and conservation easements (1,400 acres).

What Is Open

The northern section of Heil Valley Ranch is open to on-trail use only, including the Picture Rock Trail, the Wild Turkey Trail, the Ponderosa Loop, and the northern 1.2 miles of the of the Wapiti Trail. Those trails can be accessed from the Picture Rock Trailhead near Lyons.

What Is Closed

The south side of the park is closed through spring 2022. That includes the Corral Trailhead, Main Trailhead, the southern section of the Wapiti Trail, the Lichen Loop, the Overland Trail, the Schoolhouse Loop, and the Grindstone Quarry Trail.

Due to continued instability in the upper watershed, the complexities of recovery projects, and the dynamic construction timeline, there is no safe and cost-effective way to bring visitors into the south side of the park during construction. However, staff will escort volunteers and community groups to assist with recovery projects when conditions are safe and access to the area is practicable.

Safely reopening the entirety of Heil Valley Ranch remains a priority for staff. Thanks for your patience.

Safety Hazards in Closed Areas

We ask that all visitors be respectful of the closures due to safety hazards in the burn areas and the fragile landscape that needs a chance to heal.

Falling Trees

Falling trees are a serious hazard. While hazard trees have been removed from the trail corridors of open trails (see details below), there are still lots of trees in the closed areas that could fall at any time, especially during windy conditions.


Flash floods are a real concern in burn areas. The severely burned landscape is likely to flood all small and large canyons and deposit tons of debris and mud in many areas including the Heil Valley Ranch main trailhead. It is expected that rain events as small as 0.35 inches in 15 minutes or 0.75 inches in one hour could cause a flash flood at Heil Valley Ranch. Because of this, Flash Flood Warnings will be issued when rainfall at these levels are detected by radar or reported by spotters. Small Stream Flood Advisories will be issued for lower rainfall amounts, 0.5 inch in one hour. A Flash Flood Warning means immediate action is needed to protect life and property. An Advisory is issued for minor flooding that is not forecast to be a threat to life or property. However, the Advisory may be upgraded to a Flash Flood Warning if additional rain falls (see below for National Weather Service term definitions). Keep in mind that these rainfall thresholds are commonly seen as frequently as 2-3 times per year. It doesn’t take much rain on a burn scar to cause flash flooding and debris flows.

The risk of flash flooding with associated debris flows and mud flows is increased by soils previously saturated by snow or smaller rain events. The combination of conditions that can trigger a debris flow can make them unpredictable. Saturated soils are more common in the spring, and afternoon thunderstorms are common during the monsoon season (approximately June 1 through Sept. 30).

Flash flooding and debris flows may affect:

  • Marietta and Plumley canyons
  • Fire access road north from Main Trailhead parking lot to Plumley canyon
  • Main Trailhead parking lot
  • Geer Canyon and Geer Canyon Road
  • Corral Trailhead parking lot
  • Lefthand Canyon Drive
  • Lefthand Creek between Geer Canyon Drive and US36 and downstream to Longmont

Flooding is likely to be seen in Lefthand Creek all the way to Longmont and beyond. Discolored, muddy, sediment-laden, and/or ashy water is expected and water may have higher levels of certain contaminants than normal runoff.

Recovery Plan

Task Details Approx Start Date Approx End Date
Mulching Contract
Aerial Operations complete as of Aug. 9, 2021. Final demobilization of equipment week of August 16, 2021. In house seeding of Landings 2 and 3 will occur as available prior to October 15, 2021. Jan-2021 Aug-2021
Access Roads Maintenance & Restoration
The access roads have been actively maintained by BCPOS staff in the spring and summer of 2021, and will continue to be maintained by BCPOS or Boulder County Road Maintenance staff as needed. Mar-2021 Aug-2021
Park Bench Replacement Two benches were burned and will be replaced with new plaques. Aug-2021 Nov-2021
Bridge Replacement Anticipation of dangerous debris flows at the main trailhead has created uncertainty. We are currently getting a fluvial geomorphic evaluation of the upper parking lot and Wapiti bridge area, and making sure we have a better understanding of the appropriate size and location of the bridges for post-fire floods. The current plan for bridge installation at the parking lot bridge area is January/February 2022 by the Design-Build Contractor. Apr-2021 Mar-2022
Culvert Replacement Smaller road drainage culverts installed by Rec&Facilities August 2021; Larger stream crossing culverts to be designed by Design-Build team in the summer of 2021 and installed in the Fall of 2021 and the Winter of 2022. Aug-2021 Feb-2022
Mitigation and Restoration Measures Contract Start date of design delayed three months beyond anticipated start date, construction actively started August 2021, EWP funding agreement extended through March 2022. May-2021 Mar-2022
Cultural Resources Survey Project start anticipated to begin the first week of October. Fieldwork to last 11 days. Remainder of project is data processing and reporting. Oct-2021 Mar-2022
Temporary Signage, Flash Flood Signage, and Permanent Signage Some flash flood signage has been allocated to County Road Maintenance. Signposts can be removed at any time – perhaps a volunteer project. Signpost construction can start at any time. At this time, it is unknown exactly what would need to be reinstalled permanent vs. reinstalled for temporary detours. Procurement of space for raw goods or readied goods has not been made. Material cost for signposts and other raw goods have doubled in the last four months. Oct-2020 Apr-2022
Trailheads/Parking Lots & Amenities Stream and floodplain restoration work will be needed near the Corral Parking Lot due to debris flows, flash floods, and the need to protect downstream roads, houses, and the traveling public. It is anticipated that construction work will continue through June 2022 if the 2021 monsoon season brings substantial debris flows. Oct-2020 Jun-2022
Fencing (Volunteer Projects) Extension from April 2021 to November 2022 due to eagle buffer closings and heavy-equipment construction timelines; extended end date. Apr-2021 Nov-2022
Tree Planting in Critical Need Areas Trees have been ordered and should be available for planting in select areas in 2022. Jan-2022 Dec-2022
Trail Protection and Restoration Flash floods and debris flows will continue to make trail protection and restoration necessary in these first years post-fire. Apr-2021 Sep-2023
Vegetation Recovery & Protection Seeding in landing pads and other disturbance areas resulting from contract work has begun in some places, and will continue to be addressed as contract work continues. Tree planting approach at trailheads and in strategic areas throughout the park are in discussion between Forestry, Plant Ecology, Urban Forestry, and Project Manager. Three “diversity seeding” volunteer projects are earmarked for October 2021 with input from staff needed. Oct-2020 Oct-2023
Forest Disease/Insect Control Selective treatments were applied in 2021 and forest health will continue to be monitored. Jan-2021 Jan-2024
Hazard Tree Removal Trees will continue to die over the next 10 years, tree health will continue to be monitored and trees removed if they become a hazard along trails, roads, or parking lots. Nov-2020 Dec-2025
Wildlife Resources Habitat Restoration Continuous coordination with other disciplines to discuss mitigation of potential impacts to wildlife, per other project activities. Also planning for habitat enhancement or maintenance as opportunities arise Nov-2020 Dec-2025
Weed Management Weeds are a substantial problem post-fire and while we have good native growth we also have weed challenges that will need to be addressed in multiple ways Mar-2021 Dec-2025

Trail Work

Trails in the closed areas have become overgrown with weeds and vegetation. Work needs to be done to restore the trails. Almost 11 miles are currently open, just over 8 miles are closed. Of those 8, about 5 miles of trail need work.

Wildlife Concerns

Staff is working with NRCS and US Fish and Wildlife Service to ensure protection of sensitive species occurring in the project area. Staff follows federal guidance such as the Bald and Golden Eagle Protection Act when planning restoration activities.

During the 2021 nesting season, one of the three golden eagle nests that had been burned was rebuilt and had a successful fledge! Staff worked hard to keep restoration efforts away from the nest buffer to reduce disturbance.

Golden eagle

Hazard Tree Removal

Heil Valley Ranch trail and road sections that experienced high/moderate severity required complete removal of burned trees to provide safe work areas and prepare for future safe public access. The following trails and roads required clearing all trees approximately 60 feet on either side.

  • Wild Turkey Trail: 1,328 ft.
  • Wapiti Trail: 5,543 ft.
  • Lichen Loop: 4,609 ft.
  • Overland Loop: 2,251 ft.
  • Grindstone Quarry Trail: 454 ft.
  • Main Access Road: 6,479 ft.
  • Total linear distance: 20,664 ft. (3.91 miles)

Aerial Mulching

Mulching operations on Heil, private, and USFS lands began in early May and were completed in August. Wood shred mulch was applied over 2,115 acres utilizing 10,870 tons of wood.

Mulch was used to replace the cover (vegetation, litter, duff, and even the canopy of trees) that was lost during the fire. Mulching is one of the most effective emergency stabilization techniques to use post fire (Robichaud et al. 2000; Bautista et al. 2009). Mulch stabilizes soil, reduces sediment movement, prevents loss of soil productivity, and reduces risk of flooding (Bautista et al.)

The trees killed by the Cal-Wood fire were processed onsite to create the wood mulch for this effort. This was a win-win, removing hazard trees along trails and roads and reducing the need to import material. Wood shreds also have the benefit of being weed free, when compared to commonly used straw, and are not moved as easily during wind events.


Recent Photos

Emergency Alerts

Sign up to receive reverse 911 emergency messages for potential flooding. Messages are generated by the Office of Emergency Management using Everbridge Alerts. To add Heil Valley Ranch trailhead, use the following address:

  • Heil Valley Ranch Main Trailhead – 1188 Geer Canyon Rd.

Sign Up

National Weather Service Term Definitions


A warning is issued when a hazardous weather of hydrologic event is occurring, imminent or likely. A warning means weather conditions pose a threat to life or property. People in the path of the storm need to take protective action.

Cal-Wood Rainfall Guidance

  • > ¾ (.75”) of an inch in < 1 hour  > .35 inch in < 15 minutes.

Lefthand Canyon Rainfall Guidance

  • > 1 of an inch in < 1 hour  > ½ (.5”) inch in  < 15 minutes.


A watch is used when the risk of a hazardous weather or hydrologic event has significantly increased, but its occurrence, location or timing is still uncertain. A watch means that the hazardous weather is possible. People should have a plan of action in case a storm threatens, and they should listen for later information and possible warnings especially when planning travel and outdoor activities.


An advisory is used when a hazardous weather or hydrologic event is occurring, imminent or likely. Advisories are for less serious conditions than warnings, which cause significant inconvenience and if caution is not exercised, could lead to situations that may threaten life or property.

Cal-Wood Rainfall Guidance

  • ½ (.5”) inch  in < 1 hour

Lefthand Canyon Rainfall Guidance

  • 3/4 (0.75″)  inch  in < 1 hour

Post-Fire Risk Meetings

Boulder County held two Post-Fire Flood Risk Virtual Meetings in April. The potential for hillslope erosion may cause small or large landslides and debris flows in a flash flood scenario. Post-fire flood risks were discussed at the meetings, including how residents and visitors can prepare, stay alert, and be forewarned of potential risks.

Projected Costs & Funding

  • Boulder County is the local sponsor for USDA Natural Resource Conservation Service Emergency Watershed Protection Program funding for $5.3 million. This program is for post-fire interventions on local, state, and private land aimed at reducing the potential for massive flooding and soil erosion this summer. This funding covers aerial mulching, sediment control, and improved early warning systems. Boulder County, as the local sponsor, will contribute 25% of this amount ($1.2 million) to implement these important emergency actions.
  • The State of Colorado has committed to sharing the non-federal match for the Natural Resource Conservation Service Emergency Watershed Protection Cal-Wood Fire Recovery federal programs. This will cover approximately $660,000 of the county’s 25% match for the aerial mulching and erosion control.
  • The Colorado State Water Board has awarded Boulder County $550,000 for additional aerial mulching on severely burned and highly erodible soils owned by the USFS. This will cover 220 additional acres targeted to reduce soils erosion and establish vegetation.

Post-Fire Photos

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Parks & Open Space

Sharla Benjamin