Flood Control & Design Criteria Manual

Horizon Water and Environment (Horizon) is working closely with the Sonoma County Water Agency (SCWA) to revise the County’s existing Flood Control Design Criteria (FCDC) manual. The FCDC Manual provides prospective builders, engineers, and city and county planners with procedures to guide hydrologic and hydraulic analysis. The FCDC Manual also provides performance criteria to design and build flood management and drainage facilities. However, the current manual is long out-of-date.

Horizon, along with project partner PWA, is updating the existing FCDC Manual to include revised approaches for precipitation analysis, runoff calculation, hydraulic evaluation, and sediment transport analyses. The revised Manual will also incorporate new design guidance for a host of conveyance and detention facilities. While the revised FCDC Manual is primarily an engineering handbook, it is also a useful planning document that includes runoff management policies, strategies, and performance criteria. Creative solutions are being developed to manage hydrology and runoff at the project-site scale, subwatershed scale, and regional scale.

The Horizon team is working closely with representatives from the North Coast and San Francisco Bay Regional Water Quality Control Boards, as well as local municipalities and Sonoma County to guide and review the program. Sub consultant PWA is providing important contributions in the development of the technical analysis and design work.

SCWA’s vision is to develop a revised FCDC Manual that will guide hydrologic analysis and design in Sonoma County for the next generation.