YOUR BEST PRACTICE


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The field flooding of trees in winter represents the relatively newer (and chancier) practice of groundwater recharge.


Drought & laws spark interest in GROUNDWATER RECHARGE


BY SARGEANT J. GREEN T


here is recent renewed interest in groundwater recharge in California, bringing new science, institutions, markets and investments into practice.


The interest has been driven by a couple of linked factors: drought and a law change. The


policy change was the adoption of a new California law requiring groundwater controls to arrest the decline of water levels in many aquifers in California. The new law, called the Sustainable Groundwater Management Act, was instigated by a recent intense drought. That drought drastically reduced the availability of water from California’s vast river water storage and delivery systems. Shallow wells went dry, especially rural community and individual water systems. Deep wells also lost production and had to be drilled deeper causing subsidence, which is the irreversible sinking of the land surface where deep, water-swollen clays get squeezed, lose their water and collapse.


30 Irrigation TODAY | Fall 2020


These impacts prompted the California legislature to act and deliver this new law that controls groundwater use. California has had groundwater management plans for some time, but they were not enforceable. The law creates new local agencies chartered to implement controls as necessary. Avoiding the most drastic controls drives the need for more groundwater recharge.


Groundwater recharge occurs on sandy soils with deeper geology that allows for deep percolation. California’s recent renaissance in groundwater recharge is both a redeployment of what has been done in the past with a significant reinvestigation as to “where,” as well as “how.” Natural recharge continues to occur in the main rivers and streams where the coarsest materials reside. Irrigation district canals also recharge water because they often follow older stream beds that are no longer the main channel.


irrigationtoday.org


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