Lateral channel migration along a 1,500-linear-foot reach of Fountain Creek led to excessive bank erosion, subsequent agricultural land loss, and adverse sediment loading within and adjacent to the Masciantonio Trust Property boundaries in northern Pueblo County. Matrix and Tezak Heavy Equipment worked with the Fountain Creek Watershed Flood Control and Greenway District and the land owner to improve bank stability, reduce sediment loading, and protect agricultural property.
Geomorphic design principles, 1D and 2D hydraulic modeling, and sediment transport modeling guided both the realignment of the main channel to create a stable plan form and the reshaping of the channel cross-section. Parameters observed on stable, “healthy,” reference segments were used to reconfigure the stream system to convey sediment loads and withstand flows ranging from the 2,700 cfs bankfull flow to the 33,300 cfs 100-year flood flow.
The project involved constructing an earthen bankfull bench along the project reach and installing seven bendway weirs made from 36-inch, median-diameter (D50), void-filled riprap. The weirs extend an average of 70 feet into the creek, with an average of two feet above the thalweg and nine feet below the channel bottom. Channel and bank improvements were made to the Young Hollow Tributary, as well. The design also included a robust revegetation effort with over 5,000 willow and cottonwood plantings and both riparian and upland seeding.
The project reach was designated a high priority in Matrix’s Watershed Assessment of River Stability and Sediment Supply (WARSSS) study completed in 2017. This designation indicated bank instabilities were allowing water to encroach on private land and mobilizing large volumes of sediment. Our Team’s stabilization work is estimated to reduce sediment loads on Fountain Creek by over 13,000 tons per year and ultimately reclaim agricultural lands and critical habitat.