The presented economic solutions provide a good basis on which to gauge the advantage and drawbacks of policy instruments, which will be the object of the following two sections (demand-side and supply-side approaches). Moreover, even in one location, the choice of instrument will also depend on the desired level of reduction in water use: policy rankings are not necessarily invariant to changes in total water use or desired hydrologic conditions (Palazzo and Brozovic, 2014). While presented individually for clarity purposes, it should be noted that several of these are applied in combination. One core approach is to allocate allowable groundwater pumping to each well.