BriCASFR

Globally, approximately 70% of freshwater is used for agriculture / food systems, and many freshwater supplies are declining.

And examples of why supplies are declining follow: 

First, increasing temperatures result in increasing evaporation rates and in turn lower water levels.

Second, changing rainfall patterns may decrease annual precipitation rates in specific areas. Increasing frequency of droughts may result in insufficient water supplies crop growing areas.

Third, runoff from glacial melt peaks during the summer months.

Fourth, decreasing glaciers result in decreasing meltwater volumes. This reduction impacts future water supplies in downstream ecosystems, habitats, and agricultural watersheds.

Fifth, Groundwater depletion is primarily caused by sustained groundwater withdrawals or over pumping.

And the result of the unsustainable lowering of groundwater supplies include increasing costs for pumping, reducing surface water supplies, and land subsidence.

Plus, additional concerns are water quality and water contamination issues. And one example is saltwater intrusion and contamination of the water supply.