McMullin On-Farm Flood Capture and Recharge Project: Hydrologic and Hydraulic Analyses (H&H), final report | McMullin Project, Phase 1

Approval of a Hydrologic and Hydraulic Analyses (H&H) by California Department of Water Resources (DWR) is a pre-requisite for projects being funded through DWR’s Flood Corridor Program. The H&H needs to show early in the project schedule in analysis acceptable to DWR that the project will produce the anticipated flood risk reduction benefits. A Benefit:Cost (B/C) ratio provides a metric for comparing benefits from a project in relation to DWR costs for the project. In our analysis, we calculated a B/C of 1.86 for Phase 1, the diversion of 150 cubic feet per second (cfs) from the Kings River onto the project during flood flow conditions between December and May, and of 1.98 for Phase 2/3, the diversion of 500 cfs from the Kings River onto the project during the same conditions. We provide background on the project and the area that will be affected by the project (the study area), summarize our methods, and present our findings.Two large hydrologic issues face the Kings Basin: severe and chronic overdraft of about 0.16M ac-ft annually, and flood risks along the Kings River and the downstream San Joaquin River. Since 1983, downstream communities along the Kings and San Joaquin Rivers have suffered over $1B in flood damages (2013$). To help mitigate these two issues, this project proposes diverting and capturing Kings River floodwater at the James Bypass onto agricultural lands adjacent to the Kings River for conjunctive use purposes (e.g. recharge, in lieu recharge, irrigation). This project is planned in three phases: Phase 1 (Ph1) will divert 150 cubic feet per second (cfs) onto agricultural fields from December through May and 100 cfs from June through September. Fifty-five hundred acres are planned for enrollment in Ph1 with 375 acres under flood easements; 1,125 acres managed under dual purpose of accepting flood flows and being managed for farming; and the remaining acreage receiving flood flows when available for in lieu recharge. Phases 2 and 3 (Ph 2/3) together will expand enrollment to 16,000 acres with expected equivalent ratios for flood easements, dual purpose and farming. Ph2/3 is planned to have a 500 cfs flood diversion and capture capacity. We assessed hydrologic and hydraulics conditions and economics for these planned phases following the scope of work defined in Task Order 1 between Kings River Conservation District (KRCD) and Tetra Tech.

California Department of Water Resources

Flood Protection Corridor Program (FPCP)

Report by Tetra Tech Research and Development Group and Tetra Tech Surface Water Group, prepared for Kings River Conservation District for submittal to California Department of Water Resources (DWR).