The Regional Conjunctive Use Project evaluated opportunities to increase the use of surface water supplies and precision irrigation strategies within the Wyandotte Creek Subbasin. Essentially, the GSA worked with water agencies and water rights holders to identify available surface water, and with growers to identify more efficient ways to water crops and reduce water use. By developing strategies to coordinate surface water and groundwater management, the project supported a more flexible, resilient water-use option for the subbasin. The project comprised three phases: 

1. Intra-Basin Water Exchange Feasibility Study: Collaborate with water purveyors within the subbasin to expand their ability to deliver water supplies to agricultural users in the subbasin. 
2. Agricultural Surface Water Supplies Feasibility Study: Assess and use existing surface water resources in the region to provide water to agricultural users in the Wyandotte Creek subbasin. 
3. Agricultural Irrigation Efficiency: Enhance subbasin sustainability by reducing consumptive water use. This program used a mobile irrigation lab to assess landowners’ irrigation methods, provide recommendations for improvements, assist in implementing changes, and monitor and evaluate the effectiveness of those improvements.   

Work on this project has been conducted in coordination with the Thermalito Water and Sewer District (TWSD) and South Feather Water and Power Agency (SFWPA), with funding support from a California Department of Water Resources (DWR) Sustainable Groundwater Management grant.

Regional Conjunctive Use Project Fact Sheet.pdf

 

Key Accomplishments 

Intra-Basin Water Exchange Feasibility

• Completed a feasibility study evaluating opportunities for intra-basin water exchange and submitted the summary report to DWR.
• Coordinated with TWSD and SFWPA to assess the feasibility of redirecting excess surface water supplies to agricultural users.
• Developed a draft framework for a potential water exchange agreement, including a roles-and-responsibilities matrix for the GSA, water purveyors, and landowners.

Intra-Basin Water Exchange Analysis.pdf

Agricultural Surface Water Supplies Feasibility

• Completed a feasibility study and preliminary design plans and specifications, identifying infrastructure improvements needed to support surface water delivery. Reports were submitted to DWR.
• Implemented a Surface Water Conveyance Pilot Project (fall 2025 – January 2026) that included:
  • Vegetation removal to restore channel capacity
  • Berm improvements to enhance flow containment
  • Land-leveling activities to improve flow routing and conveyance efficiency
• Completed pilot project documentation and submitted all materials to DWR.

Agricultural Irrigation Efficiency

• Completed a feasibility study evaluating irrigation practices, potential efficiency improvements, and the applicability of precision irrigation techniques within the subbasin. The study was submitted to DWR.
• Based on stakeholder input and feasibility findings, the project team — with DWR approval — shifted the pilot effort from irrigation efficiency to surface water conveyance improvements, better aligning the project with community-identified priorities around flood management and conveyance capacity.

Ag Irrigation Efficiency Analysis.pdfPalermo Pilot Project Summary.pdf

 Project Benefits

• Reduced Groundwater Demand: By enabling growers to use surface water instead of groundwater pumping, the project lays the foundation for reducing groundwater demand and improving groundwater conditions over time.
• Improved Conveyance Infrastructure: Vegetation management, berm improvements, and enhanced channel capacity improved the efficiency of surface water delivery throughout the subbasin.
• Flood Risk Reduction: Pilot project improvements enhanced flow routing and reduced the potential for flood-related impacts in areas prone to seasonal high flows.
• Groundwater Recharge: Use of existing conveyance pathways supports direct recharge through seepage in addition to reduced pumping.
• Strengthened Collaboration: Engagement with the GSA, water purveyors, agricultural users, and community members has strengthened partnerships and positioned the subbasin for future implementation of conjunctive use projects.

Final Project Recap Presentation 03.19.2026.pdf

 

Consultant: Larry Walker Associates  

Total Project Budget: $753,000

WyC Surface Water Supplies Public Meeting Presentation 11.07.2024.pdfRegional Conjunctive Use Presentation to Board_04.24.2025.pdf

 Project Timeline