McMullin On-Farm Flood Capture and Recharge Project — California Department of Water Resources
The San Joaquin Valley (SJV) faces two large hydrologic issues: severe and chronic groundwater overdraft and flooding risks along major rivers. Capturing sufficient flood flow volumes for groundwater recharge could help address these two pressing issues of groundwater overdraft and flood risks. However, snow pack, precipitation, reservoir volume and flood risks affect reservoir releases, leading to flood flows along the major rivers which vary greatly in their frequency, duration and magnitude. This variance makes dedicated, engineered recharge approaches using public lands expensive.
Within this complex regulatory and hydrologic environment, groundwater recharge opportunities still remain. Promoting flood flow capture and recharge on private agricultural lands is an untapped opportunity that could increase groundwater supplies through direct and in lieu groundwater recharge. This project follows upon the NRCS Conservation Innovation Grant (CIG) pilot project envisioned and led by Dr. Philip Bachand of Tetra Tech (dba Bachand & Associates) (Project number 68-9104-0-128, Focusing on demonstrating cost effective agricultural BMPs - On-Farm Flood Flow Capture - to retain and infiltrate storm waters, Kings Basin, CA). That project quantified achievable infiltration rates, identified logistical challenges, modeled long-term effects to groundwater and estimated the on-farm economics. This project extends those findings to a farm-scale project under Phase 1, with over 1100 acres of farmland planned for dual use (farming, flood capture), nearly 400 acres in flood easement and 4500 acres for farming. Subsequent phases are planned to include 16,000 acres of farmland enrolled in the program.
This project is awarded to Kings River Conservation District through a $5M grant from Flood Corridor program, Department of Water Resources. A $2M matching grant is provided by Terranova Ranch. This project focuses on demonstrating cost effective agricultural BMPs to retain and infiltrate stormwater. These methods are alternative approaches to more engineered retention basins and could provide flexibility to farmers in implementing stormwater retention programs that are compatible with the logistics of crop production. Integral to this project will be demonstrating the related infrastructure to distribute water to fields during stormflow conditions. The project’s goal is to evaluate the effectiveness of this approach, identify potential constraints, and quantify infiltrated water through a hydrologic budget. Deliverables planned for this project includes infrastructure improvements, a validation study and fact sheets for technology implementation.
KRCD serves at the project prime and contracting agency with DWR. Dr. Philip Bachand at Tetra Tech serves as the Technical Lead on the project. Tetra Tech has completed an Hydrologic and Hydraulic Study showing a benefit:cost ratio of nearly 2 over a 50-year period. Tetra Tech will conduct the CEQA, develop the specifications for necessary infrastructure, work with neighboring farmers to develop a regional plan for capture and recharge of flood water, and design and implement necessary studies to validate the technology at the larger farm complex scale and address technical challenges associated with water resources, water quality and economics.