Between 2023 and 2025, the City collaborated with Kittitas County and outside consultants to execute several interrelated projects designed to provide an in-depth analysis within the City limits and Urban Growth Area (UGA) of urban flooding associated with Whiskey and Mercer Creeks.
Supported by two Department of Ecology grants ($400,000.00 from the Flood Control Assistance Account Program and $130,000 from the Stormwater Capacity Grant program) as well as City and County match funding, the following activities were completed:
- Stormwater Asset Data Collection of the City’s entire Storm System
- Drainage basin mapping
- Re-mapping and Modeling of the City’s Storm System
- Identification of undersized storm system components
- Identification of long-term capital projects aimed at culverts and outfalls
- Integration of Storm System Modeling into the Urban Flood Model
- Comparison of the Urban Flood Model with the existing County model
- Re-evaluation of current flood maps
These projects, completed in June 2025, strengthened the City’s ability to track, manage, and maintain stormwater infrastructure, improving flood mitigation and long-term planning. These projects also helped to identify mitigation actions for the 2024 Kittitas County Hazard Mitigation Plan and will be used to inform Kittitas County’s flood map updates for Whiskey and Mercer Creeks.