Groundwater Study Assesses Potential for Contamination of Drinking-Water Aquifers in LA

Contaminated groundwater found at shallow depths in southern Los Angeles County has the potential to migrate to deeper aquifers, according to a scientific study just published by the U.S. Geological Survey and the Water Replenishment District of Southern California. These results confirm previous studies conducted by WRD and the U.S. Environmental Protection Agency. Over two million residents get approximately 60 percent of their drinking water supply from these deeper aquifers.

The study focused on aquifers in the 280-square mile Central Groundwater Basin, one of the most heavily used groundwater basins in southern California. The study did not analyze treated tap water delivered to consumers. Groundwater is typically treated by water distributors prior to delivering it to customers to ensure compliance with water quality standards for human health. The regionally coordinated investigation used new and existing data, supplemented with new geologic interpretation techniques. Water chemistry data and groundwater simulation models were used to understand the interconnections and water flow between different aquifer layers.

"Our investigation concluded that contaminated groundwater found at shallow depths in the northeastern portion of the Central Groundwater Basin could migrate to greater depths where many drinking water supply wells are located," said Eric Reichard, Director of the USGS California Water Science Center. "Now that we've established that the potential for migration is there, the next step is to assess the specific risk this may pose to the main drinking water aquifers."

There are multiple sites in the northeast portion of the basin where shallow groundwater contamination is already being investigated and remediated under the oversight of several federal and state regulatory agencies. The results of this new study will allow WRD to anticipate possible future contaminant migration and to plan accordingly to protect uncontaminated areas. Additionally, regulatory agencies can use the study results to inform future monitoring and cleanup actions for contaminated sites located in the Central Groundwater Basin.

Source

Media

Taxonomy

• Groundwater Recharge
• Aquifer Recharge