Managed Aquifer Recharge: Lessons Learned in Southern California

For over 75 years, the Central and West Coast Groundwater Basins in southern California have practiced managed aquifer recharge (MAR) to overcome serious overdraft that had led to plunging groundwater levels, depletion of supply, drying up of wells, and seawater intrusion.   Over time, the various MAR activities implemented by numerous agencies to combat the overdraft included the construction and operation of a thousand acres of spreading grounds to capture and infiltrate stormwater, urban runoff, imported water, and recycled water, construction of nearly 300 injection wells along 16-miles of coastline to form a hydraulic ridge as a barrier to seawater intrusion, and an “In-Lieu” program to reduce pumping.  Since the formation of the Water Replenishment District of Southern California (WRD) in 1959, nearly 9.5 million acre-feet of water has been returned to the aquifers under MAR programs to maintain balance in the groundwater basins.  Over this time frame, lessons have been learned at all three MAR operations which have led to improvements in recharge activities.  The history of MAR operations in the Central and West Coast Basins, along with the lessons learned, will be discussed at the conference.