- USGS webpage for Groundwater Quality
- A Guide to Water Quality Requirements Under the Sustainable Groundwater Management Act (Stanford’s Water in the West)
- Guide to Protecting Drinking Water Quality under SGMA (Community Water Center)
- Protecting Groundwater Quality in California (Environmental Defense Fund)
Groundwater quality can be impacted by a host of natural and anthropogenic sources.
Additionally, contamination can occur from a single “point” source, like a decommissioned military base or by many distributed sites, commonly referred to as “non-point” source contamination, like nitrate contamination resulting from fertilizers used on many fields collectively.
Groundwater quality can vary between aquifers in the same basin, with shallow “unconfined” aquifers being particularly prone to contamination. Thus, groundwater monitoring is usually preformed in “nested” monitoring wells that enable sampling of individual aquifers separately.
Even within a single aquifer, groundwater quality can change with elevation. Groundwater quality generally degrades with increasing depth within an aquifer. Thus declining groundwater levels can lead to poorer water quality and concentration of contaminant.
State Water Board Groundwater Quality Information
The Groundwater Ambient Monitoring and Assessment (GAMA) Program is California’s comprehensive groundwater quality monitoring program that was created by the State Water Resources Control Board (State Water Board) in 2000. The GAMA Program is based on interagency collaboration with the State and Regional Water Boards, Department of Water Resources, Department of Pesticide Regulations, U.S. Geological Survey, and Lawrence Livermore National Laboratory, and cooperation with local water agencies and well owners.
The main goals of GAMA are to improve statewide comprehensive groundwater monitoring and increase the availability to the general public of groundwater quality and contamination information.