Pollution (Chemical and Biological)

From the second half of the 19th century, land reclamation has transformed the Sacramento-San Joaquin Delta (Delta). The landscape of the Delta has gone from a network of shifting waterways and tidal marshland to channels and islands fixed in position by hardened levees.

Regional Water Availability Assessments are scientific assessments of water availability in different hydrologic regions across the Nation. In the Upper Colorado River Basin, the USGS will conduct a focused assessment of how snowpack and snowmelt influence hydrology and water quality, and an integrated and comprehensive assessment of multiple water quantity, quality and use factors.

Regional Water Availability Assessments are scientific assessments of water availability in different hydrologic regions across the Nation. In the Delaware River Basin, the USGS will conduct a focused assessment of increasing freshwater salinity and an integrated and comprehensive assessment of multiple water quantity, quality and use factors.

The Proxies Project is a series of studies to improve our understanding of water contaminants and water quality hazards. These studies develop models and technical approaches for estimating concentrations and assessing risk associated with: - harmful algal blooms (HABs) - per- and polyfluoroalkyl substances (PFAS) - 12 elements of concern (EoC)

Wildfires pose a substantial risk to water supplies because they can lead to severe flooding, erosion, and delivery of sediment, nutrients, and metals to rivers, lakes, and reservoirs. The USGS works with federal and state land managers and local water providers to monitor and assess water quality after wildfires in order to help protect our Nation’s water resources.

Lead Researcher: Travis Schmidt Project Manager: Melissa Schaar Water-Quality Field Lead: Chad Reese

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 previous core version, MODFLOW-2005, is actively maintained and supported as well.

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.

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 at least 10 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...

Substantial advances in water science, together with emerging breakthroughs in technical and computational capabilities, have led the USGS to develop a Next Generation Water Observing System (NGWOS). The USGS NGWOS will provide real-time data on water quantity and quality in more affordable and rapid ways than previously possible, and in more locations.

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...