California cities and towns only get 10% of the water. Farmland gets 80% (or somewhat less depending on how you account for it), yet only produces 2% of the state's GDP. The problem is that they are STILL growing the size of the agriculture sector, planting more almond trees for example, even while the existing almond trees are dying from salt poisoning. The reason the overall GDP hasn't been hurt yet is due to the fact that so much of the water is used for so little of the state's income. When the groundwater is all gone due to lack of planning, things may actually change.