50 Years of Successful Groundwater Recharge Using Recycled Municipal Wastewater, Montebello Forebay Spreading Grounds, Los Angeles County, California

Managed aquifer recharge utilizing recycled municipal wastewater has occurred successfully at the Montebello Forebay Groundwater Recharge Project (MFGRP) in southern Los Angeles County, California, since August 20, 1962.  This is the oldest planned groundwater recharge project using recycled water in California.  The MFGRP is a joint surface-spreading project between the Water Replenishment District of Southern California (WRD), which manages artificial replenishment of the groundwater basins, the Los Angeles County Sanitation Districts (LACSD), which provides the recycled water and oversees permit compliance, and the Los Angeles County Department of Public Works (LACDPW), which operates and maintains the Rio Hondo and San Gabriel River spreading grounds.  To date, over 1.6 million acre-feet (AF) of recycled water has been recharged at the MFGRP to help replenish the Central and West Coast Groundwater Basins. 

 The MFGRP is an indirect potable reuse project heavily regulated by the California Department of Public Health (CDPH) and Los Angeles Regional Water Quality Control Board (LARWQCB) for protection of human health and of beneficial uses of groundwater.  There are over 400 drinking water wells in the groundwater basins of which 23 wells are within 500 feet of the spreading grounds and have been receiving the recharged recycled water for decades.  Currently, about 44,000 AF per year of disinfected tertiary municipal wastewater is being delivered to the spreading grounds for groundwater recharge. 

 Recycled water is a sought-after replenishment source since it is highly reliable, cost effective, locally controlled, and drought resistant. A summary of the last 50 years of the project, including the scientific research performed, and plans for the future will be presented at the conference.