Dad Clark Gulch Downstream of Wild Iris Run
Highlands Ranch, Colorado
This 1,900-foot reach of Dad Clark Gulch, located in Highlands Ranch, Colorado, was severely eroding with downcutting up to 7-feet, which triggered extensive channel widening and bank erosion that threatened storm sewer outfalls, a pedestrian trail crossing, and the health of riparian vegetation. Several large cottonwood trees and shrubs masses were undermined from the erosion and starting to fall into the stream. A natural stream restoration approach was undertaken to raise the stream bed and restore floodplain connectivity and groundwater levels supporting the riparian vegetation.
Restoration involved developing a riffle-pool system and reclaiming the meandering channel. Bioengineering methods integrating willow logs and stakes, herbaceous riparian plugs, and large wood from downed trees were incorporated to stabilize banks. An extensive revegetation plan reclaimed the corridor and included native seeding and variety of riparian trees, shrubs, and wetland herbaceous plugs. Fallen trees were also repurposed for floodplain overbank areas and strategically placed to provide habitat and hydraulic roughness. The natural restoration approach was viewed favorably by the U.S. Army Corps of Engineers with regards to Section 404 permitting, allowing the project to be authorized under Nationwide 27 Permit for Aquatic Habitat Restoration, Establishment, and Enhancement Activities. Floodplain permitting included preparation of a Conditional Letter of Map Revision prior to construction and preparation of a Letter of Map Revision following construction.
Mile High Flood District
Stormwater & Floodplain Management