Deep Groundwater Conditions Report - Westlands Water District

Safe YieldSafe yield or current perennial yield is the amount of groundwater that can be extractedwithout lowering groundwater levels over the long term. Current perennial yield can be determinedby plotting the amount of groundwater pumped in one year versus the average change in groundwaterlevel in the basin for that year. Data for 1976 to present were plotted and a “best fit” was drawn.The intersection of the best fit with the line showing zero groundwater level change as shown inFigure 10 indicates the current perennial yield of groundwater to be approximately 200,000 AF.150ChangeLinear (Change)100Change in Groundwater Elevation in Feet500(50)(100)(150)0 100,000 200,000 300,000 400,000 500,000 600,000 700,000Pumpage in Acre/Feet 1976 through 2010Figure 10: Change in Groundwater Elevation versus Pumping.16