C-BT and WG Water Quality
Comprehensive Water Quality Monitoring Across Our Systems
Northern Water’s service area covers more than 2,574 square miles, including an extensive network of lakes, reservoirs, rivers, and canals. Protecting water quality across this system is vital—not just for drinking and recreation, but also for supporting aquatic life and healthy fish habitats. To safeguard these resources, Northern Water runs robust monitoring programs that track and assess water quality throughout our system. These efforts ensure the water we deliver meets rigorous standards and remains safe, reliable, and sustainable for all uses.
Colorado-Big Thompson and Windy Gap Water Quality Monitoring
Since 1991, Northern Water has collected and analyzed water quality data across the C-BT and Windy Gap systems. What began as a focused effort has evolved into a comprehensive monitoring network that spans the Continental Divide and includes eight major watersheds. Sampling takes place in streams, canals, lakes and reservoirs, with frequencies ranging from weekly to monthly depending on the site and program.
Monitored parameters include nutrients, major ions, metals, general chemistry, phytoplankton and zooplankton. Data collected through this program are used to:
- Track current conditions and long-term trends in water quality
- Evaluate the impacts of floods, wildfires, spills and other disturbances
- Assess the influence of C-BT and Windy Gap water deliveries on stream systems
- Support compliance with state and federal water quality regulations
- Inform water quality modeling, permitting and management decisions
Three Lakes Monitoring
The Three Lakes system—comprising Lake Granby, Shadow Mountain Reservoir and Grand Lake—is a critical component of the C-BT Project’s collection system in the Upper Colorado River Basin. Since 2008, Northern Water has conducted extensive monitoring in these water bodies, with targeted efforts to address specific concerns such as water clarity in Grand Lake. Data collected from the Three Lakes system are integrated into the broader C-BT and Windy Gap monitoring programs to track changes over time and support informed, long-term water management.
Aquatic Plants Monitoring
Algae and aquatic plant growth in East Slope canals can reduce flow capacity and create operational challenges. To manage these impacts, Northern Water collects algal samples to identify species and monitor changes over time. Targeted treatments are then applied only where needed, helping to minimize herbicide use, protect drinking water quality and maintain efficient canal operations.
Windy Gap Firming Project Monitoring
As Northern Colorado continues to grow, regional projects like the Windy Gap Firming Project (WGFP) are essential for meeting future water demands while also protecting the environment, supporting agriculture, and preserving the region’s quality of life. A key component of the WGFP is the construction of Chimney Hollow Reservoir on the East Slope in southern Larimer County.
As part of the project’s permitting requirements, Northern Water conducts extensive water quality monitoring to ensure environmental standards are upheld. This monitoring program:
- Confirms that project operations do not negativelyimpactwater quality
- Assesses the effectiveness of mitigation and enhancement measures
- Collects data from multiple West Slope sites to guide ongoing stewardship and adaptive management
