Water Georgetown Lake Outlet Improvement

Project Highlights

• Supported flood recovery efforts following the 2013 St. Vrain Creek flood, with flows exceeding 12,000 cubic feet per second.
• Designed repairs for an embankment dam, two augmentation reservoirs, and seven embankment breaches along a four-mile stretch of the creek.
• Improved flood resilience while supporting reservoir capacity restoration and the recovery of riparian and wildlife habitat.

Project Description

Following the historic September 2013 flooding in Boulder County, CO, a four-mile stretch of St. Vrain Creek between Lyons and Hygiene experienced significant damage. Heavy rainfall in the mountains west of Lyons produced a 500-year flood event, with flows exceeding 12,000 cubic feet per second and causing widespread impacts to embankments, reservoirs, and surrounding areas.

The Georgetown Lake Outlet Improvement project was part of a broader effort to repair and restore critical infrastructure along the creek while improving long-term flood resilience. Engineering services included the repair of an embankment dam, two augmentation reservoirs, and seven embankment breaches. The project was designed to meet the requirements of the NRCS Emergency Watershed Protection Program and FEMA funding requirements.

Preliminary and final designs addressed repairs to an existing slurry wall and a 30-foot-tall embankment, along with replacement of low-level outlet works. Repairs to the embankment breaches were designed to better withstand future flood flows while reducing the potential for underseepage and internal erosion. The project also supported the restoration of reservoir capacity, riparian areas, and wildlife habitat throughout the affected reach.

Work performed by Engineering Analytics, Inc., now part of MacKay.