The 6400 South Tributary Stabilization project was initiated by Castle Rock Development Company to stabilize an unnamed tributary near 6400 S. Monarch Boulevard in Castle Rock, Colorado. With design services provided by AECOM and construction by Naranjo Civil Constructors, the project addresses ongoing channel erosion and protects adjacent infrastructure, utilities, and nearby school facilities. The improvements include comprehensive grading and channel realignment, construction of multiple drop structures, and installation of bank stabilization measures to improve long-term channel resiliency and reduce sediment transport. In addition, the project features riprap armoring, site revegetation, and coordination with surrounding development to ensure stormwater compliance and minimize downstream impacts. The work supports future growth while enhancing drainageway stability and protecting community assets.