Types of Water

MODFLOW is the USGS's modular hydrologic model. MODFLOW is considered an international standard for simulating and predicting groundwater conditions and groundwater/surface-water interactions. MODFLOW 6 is presently the core MODFLOW version distributed by the USGS.

The Delta of the Sacramento and San Joaquin rivers provides drinking water supplies to two-thirds of Californians, and is a fragile ecosystem home to threatened and endangered species. The CASCaDE project builds on several decades of USGS science to address the goals of achieving water supply reliability and restoring the ecosystems in the Bay-Delta system.

Did you know that earthquakes can cause changes in groundwater levels? Very large earthquakes can even cause water-level fluctuations in some wells thousands of miles away, depending on the local geological conditions around the well.

Karst terrain is created from the dissolution of soluble rocks, principally limestone and dolomite. Karst areas are characterized by distinctive landforms (like springs, caves, sinkholes) and a unique hydrogeology that results in aquifers that are highly productive but extremely vulnerable to contamination.

The U.S. Geological Survey is integrating its water science programs to better address the Nation’s greatest water resource challenges. At the heart of this effort are plans to intensively study several Integrated Water Science (IWS) basins—medium-sized watersheds (10,000-20,000 square miles) and underlying aquifers—over the next decade. The IWS basins will represent a wide range of environmental...

The Next Generation Water Observing System (NGWOS) supports water availability assessments, management, and prediction by enhancing water observations in basins that represent major U.S. hydrologic regions. NGWOS provides high-resolution, real-time data on water quantity, quality, and use, as well as advance the development and application of new sensor technologies and remote sensing methods.

The Next Generation Water Observing System provides high-fidelity, real-time data on water quantity, quality, and use to support modern water prediction and decision-support systems that are necessary for informing water operations on a daily basis and decision-making during water emergencies. The Illinois River Basin provides an opportunity to implement the NGWOS in a system challenged by an...

The Next Generation Water Observing System (NGWOS) provides high-fidelity, real-time data on water quantity, quality, and use to support modern prediction and decision-support systems that are necessary for informing water operations on a daily basis and decision-making during water emergencies. The headwaters of the Colorado and Gunnison River Basins provide an opportunity to implement NGWOS in a...

The Next Generation Water Observing System (NGWOS) supports water availability assessments, management, and prediction by enhancing water observations in basins that represent major U.S. hydrologic regions. The Delaware River Basin was the first Integrated Water Science basin selected, providing an opportunity to implement the NGWOS program in a nationally important, complex interstate river...

The Water Quality of San Francisco Bay Research and Monitoring Project measures changes in water quality along the deep channel of the San Francisco Bay-Delta system using submersible sensors and discrete water samples. Learn more about how we collect and measure water-quality data.

The Research Vessel David H. Peterson begain service with the U.S. Geological Survey in 2015. Named after a founder of the Water Quality of San Francisco Bay Research and Monitoring Project, this vessel is a high-tech scientific platform for estuarine research. Learn more about how the R/V David H. Peterson makes our research possible.

This website compiles USGS resources and data related to principal aquifers including Aquifer Basics, principal aquifers maps and GIS data, and the National Aquifer Code Reference List.