An immediate need following catastrophic fires like the Cameron Peak Fire is to reduce erosion on hillslopes. High severity fires burn away the majority of vegetation and topsoil on hillslopes leaving hydrophobic (water repellent) soil. Hydrophobic soils with little vegetation can be heavily impacted by even small rain events leading to severe erosion and sediment, ash, and debris flowing downhill into waterways. When our waterways are inundated with excess water, sediment, and debris, post-fire flooding occurs impacting downstream values, aquatic populations, communities, and roadways.
To address this need we took a two-fold approach: aerial mulching and volunteer hillslopes stabilization events. Aerial mulching utilizes helicopters to drop mulch onto high severity burn areas in priority subwatersheds. Subwatersheds are prioritized using burn severity mapping alongside other datasets which show the risk to waterways, roads, and communities. Using helicopters to mulch allows us to address larger swaths of land more efficiently. Mulch can be transported to helicopter landing sites or can be sourced on site by cutting and chipping burned trees. When mulch is dropped onto burned hillslopes it can help slow the flow of water moving downhill and aid in water retention. Water retention helps bring moisture back into the soil which is critical for revegetation. Our volunteer events utilized a mix of mulching, seeding with native seed, and installing wattles. Native seed helps to stabilize soils by reintroducing vegetation and their root structures while mulch helps to slow and retain water allowing vegetation to reestablish. Wattles are installed on slopes to prevent sediment from flowing downhill which reduces soil loss and incising of gullies and rills.
On average, aerial mulching costs $3,000 an acre. No small cost when Cameron Peak Fire burned over 208,000 acres. We sourced just under $5 million in grant funds for aerial mulching and this was used to treat 1,922 acres in the Big Thompson, which took less than three weeks!
Cameron Peak Hillslope Stabilization
1,922 acres mulched across North Fork and Buckhorn subwatersheds
Spread native seed across 50 acres
Nearly $5 million in federal, state, and local funds acquired for aerial mulching operations
Burned trees removed and mulched on 4 private properties
Installed 408 wattles with volunteers