Unified Interior Regions
California
The Southwest Region includes California, Nevada, and Arizona. The Regional Office, headquartered in Sacramento, provides Center oversight and support, facilitates internal and external collaborations, and works to further USGS strategic science directions.
States L2 Landing Page Tabs
The Southwest Region includes California, Nevada, and Arizona. The Regional Office, headquartered in Sacramento, provides Center oversight and support, facilitates internal and external collaborations, and works to further USGS strategic science directions.
Remote Sensing Coastal Change
We use remote-sensing technologies—such as aerial photography, satellite imagery, structure-from-motion (SfM) photogrammetry, and lidar (laser-based surveying)—to measure coastal change along U.S. shorelines.
January 2021: Evaluation of debris flow activity in recent California Burn Areas following atomospheric river event
The January 2021 atmospheric river event produced heavy rainfall in some areas burned by wildfires in 2020. The Landslide Hazards Program (LHP) staff has evaluated the debris-flow activity in several areas. The locations are: The Carmel Fire, the CZU Lightning Complex Fire (San Mateo and Santa Cruz), the Dolan Fire, and the River Fire burn areas.
Reports by date are below. Photos will...
Longfin Smelt Distribution in the Coastal Pacific Ocean
Longfin Smelt (Spirinchus thaleichthys) is a pelagic fish species found in waters along the Pacific coast, from Alaska to central California. Its complex life cycle makes it vulnerable to threats in both freshwater and at sea. Longfin Smelt is listed as a threatened species by the state of California.
Dynamic coastlines along the western U.S.
The west coast of the United States is extremely complex and changeable because of tectonic activity, mountain building, and land subsidence. These active environments pose a major challenge for accurately assessing climate change impacts, since models were historically developed for more passive sandy coasts.
U.S. West Coast and Alaska Marine Geohazards
Marine geohazards are sudden and extreme events beneath the ocean that threaten coastal populations. Such underwater hazards include earthquakes, volcanic eruptions, landslides, and tsunamis.
Devastating earthquakes in Japan (2011) and Chile (2010) that spawned pan-oceanic tsunamis sent a sobering reminder that U.S. coastlines are also vulnerable to natural disasters that originate in...
Cascadia Subduction Zone Marine Geohazards
Societal Issue: Uncertainty related to rupture extent, slip distribution, and recurrence of past subduction megathrust earthquakes in the Pacific Northwest (northern CA, OR, WA, and southern BC) leads to ambiguity in earthquake and tsunami hazard assessments and hinders our ability to prepare for future events.
Assessing Sediment Nutrient Storage and Release in California's Sacramento-San Joaquin Delta
Sediments represent an important pool of nutrients in the Sacramento-San Joaquin Delta (Delta). The exchange of nutrients between the water column and the benthos impacts water quality and effects phytoplankton, harmful algal blooms, aquatic vegetation, and drinking water quality. To date, there is very limited information about nutrient pools in Delta sediments, nor how these nutrients are...
Sediment transport between estuarine habitats in San Francisco Bay
This research is part of the project “Sediment Transport in Coastal Environments”
San Francisco Bay geomorphology
This research is part of the project “Sediment Transport in Coastal Environments”
Drag and sediment transport: conditions at the bottom boundary
Research on bed sediment grain size, bedform morphology, vegetation characteristics, and sediment resuspension and transport is part of the Sediment Transport in Coastal Environments project.
2013 Springs Fire, Ventura County, California Landslide Monitoring Site
Recent Monitoring Data
U.S. Highway 50, CA Landslide Monitoring Site
Recent Monitoring Data
Hydrodynamic and sediment transport data from San Pablo Bay and Grizzly Bay, California, 2019
USGS scientists collected hydrodynamic and sediment-transport data at shallow water sites in San Pablo Bay and Grizzly Bay, in northern San Francisco Bay between June and November 2019. The data were collected to determine hydrodynamic forcing, bed roughness, suspended-sediment concentration, and physical properties of the sediment bed. This data release includes hydrodynamic and sediment...
Diets and Stable Isotopes of Fishes in Rodeo Lagoon, California, 2016-2017
This dataset includes lab data for fish, fish diets, and stable isotopes for fish tissue, vegetation, and invertebrates collected during daylight hours in the Rodeo Lagoon and Lake in Golden Gate National Recreation Area at the Pacific Coast, USA during 2016 and 2017. This data release includes all animal taxa, and isotope values included in the analysis.
Hydrogeology of the Adelaida Area, San Luis Obispo County, CA
The USGS is conducting a comprehensive evaluation of groundwater resources of the Adelaida area. Use this map to explore the hydrogeology of the area, including land use, geology, and USGS hydrologic data by watershed or water management district.
Electrical Resistivity Tomography Data at Elizabeth Lake, Los Angeles County, California, 2019
The Santa Clara River Lakes, located along the San Andreas fault 19 miles northwest of Palmdale, California, were placed on the state’s “303(d) List” or “Impaired Water List” in 1996 for eutrophic conditions, high pH, and low dissolved oxygen. In 2016, the state adopted a Total Maximum Daily Load (TMDL) for nutrients (nitrogen and phosphorus) in the Santa Clara River Lakes. This study focuses...
California shorelines and shoreline change data, 1998-2016
Mean high water shorelines along the coast of California for the years 1998-2002, 2015, and 2016 were extracted from LiDAR digital elevation models using ArcGIS. The Digital Shoreline Analysis System was used to calculate net shoreline movement between the pre-El Niño and post-El Niño shorelines, as a proxy for sandy shoreline change throughout the El Niño winter season. For a longer-term...
Pilot study on bathymetric change analyses in the Sacramento-San Joaquin Delta, California
This pilot study explores historic bathymetric change in the Delta. The earliest comprehensive surveys that covered a large portion of the Delta were conducted in the 1930s. These historic surveys are compared to recent surveys to document how sedimentation and erosion have changed the Delta. We selected regions for the pilot study based on availability of data, critical habitats, and...
California Groundwater Ambient Monitoring and Assessment (GAMA) Program Shallow Aquifer Assessment Study Unit Boundaries and Grid Cells for Assessment of Groundwater Resources
The California Groundwater Ambient Monitoring and Assessment Program (GAMA) is a statewide assessment of groundwater quality designed to help better understand and identify risks to groundwater resources. GAMA is implemented by the California State Water Resources Control Board. The U.S. Geological Survey (USGS) is the technical lead for the Priority Basin Project (PBP), one of the
California Groundwater Ambient Monitoring and Assessment (GAMA) Program Shallow Aquifer Assessment Study Unit Boundaries and Grid Cells for Assessment of Groundwater Resources
The California Groundwater Ambient Monitoring and Assessment Program (GAMA) is a statewide assessment of groundwater quality designed to help better understand and identify risks to groundwater resources. GAMA is implemented by the California State Water Resources Control Board. The U.S. Geological Survey (USGS) is the technical lead for the Priority Basin Project (PBP), one of the
Zooplankton Survey of the Northern Sacramento-San Joaquin Delta, California, 2016-2018
This data set contains information on zooplankton and associated environmental parameters for sampling conducted in California's northern Sacramento-San Joaquin Delta between May 2016 and April 2018. Macrozooplankton were sampled with horizontal tows (water surface) of a 50 cm-diameter conical plankton net that was 150cm long with 102µm mesh. Samples were preserved in the field in 10%
Potential Explanatory Factors for Groundwater Quality in the Northern Sierra Nevada Foothills Domestic-Aquifer Assessment Study Units, 2015-2017: California GAMA Priority Basin Project
This data release codifies and attributes explanatory factors that could potentially impact groundwater quality at 142 groundwater sites (wells or developed springs) used for domestic water supply and 310 groundwater sites used for public water supply in the northern Sierra Nevada foothills. Water quality from domestic groundwater sites was assessed as part of the California State Water Resou...
Aquifer test data for the Belridge multiple-well monitoring site (BWSD), Kern County, California
To determine aquifer characteristics, pneumatic slug tests were performed on selected zones and aquifers at a monitoring site near the North and South Belridge oil fields in the Southern San Joaquin Valley in Kern County. On November 19th and 20th, 2018, pneumatic slug tests were performed at five monitoring wells located at the multiple-well groundwater-monitoring site BWSD (28S/21E-08
Bathymetry and acoustic backscatter data collected in 2008 offshore Tijuana River Estuary, California during USGS Field Activity S-5-08-SC
In 2008 the USGS collected bathymetry and acoustic-backscatter data offshore the Tijuana River Estuary, California. Mapping was conducted as part of the Tijuana Estuary Fine Sediment Fate and Transport Demonstration Project, which was developed by a number of State of California, federal, and private industry partners to provide information about the directions, rates, and processes of fine...
Prediction of Flooding Now and Into the Future: a geonarrative on coastal storms
The USGS is conducting a comprehensive evaluation of groundwater resources of the Adelaida area. Use this map to explore the hydrogeology of the area, including land use, geology, and USGS hydrologic data by watershed or water management district.
This USGS geonarrative (Esri Story Map) summarizes the USGS response and findings after the M6.4 on July 4 and M7.1 on July 6, 2019 in Searles Valley, Southern California, and includes links to USGS research publications and data releases.
A data visualization exploring the relationship between nutrient distribution and phytoplankton under different conditions across the San Francisco Delta and Estuary. Assessing distribution and abundance aids understanding of how managing nutrient supplies affects aquatic food webs, helping managers evaluate the potential environmental benefits of future nutrient reduction efforts against costs.
Data visualization tool created for California's Bay-Delta Regional Monitoring Program. This web application visualizes nutrients and phytoplankton spatially and temporally for data collected in 2018.
RestoreNet is a networked ecological experiment on the cutting-edge of restoration science. The experiment sites span dryland ecoystems of the southwest U.S.
Domestic wells provide drinking water supply for approximately 40 million people in the United States. Knowing the location of these wells, and the populations they serve, is important for identifying heavily used aquifers, locations susceptible to contamination, and populations potentially impacted by poor-quality groundwater.
A geonarrative summary of the USGS report that provides a broad perspective on California’s exposure to volcanic hazards. By integrating volcanic hazard information with geospatial data on populations, infrastructure, and resources, the results provide estimates of impacts to people and our environment if an eruption were to occur.
The GAMA-PBP Public-Supply Well Results data viewer allows the user to visualize and download California water-quality data and trends for1974 - 2014. Groundwater-quality data for 38 inorganic constituents are captured and can be downloaded for individual sites or by grid cell.
Figure 4. Yearly Distribution (2007-2019) of Tamarisk Beetle (Diorhabda spp.). Annual tamarisk beetle distribution map. Provided by RiversEdge West. 2020. Used with permission from Ben Bloodgood, Program Coordinator.
The California Seafloor Mapping Program (CSMP) is a cooperative program to create a comprehensive coastal and marine geologic and habitat base map series for California's State waters. Initiated in 2008, the CSMP has collected bathymetry and backscatter data that are being turned into habitat and geologic base maps.
The Coastal Storm Modeling System (CoSMoS) makes detailed predictions (meter-scale) over large geographic scales (100s of kilometers) of storm-induced coastal flooding and erosion for both current and future SLR scenarios, as well as long-term shoreline change and cliff retreat. Several versions of CoSMoS have been implemented for areas of the California coast.
Toward physics-based nonergodic PSHA: A prototype fully-deterministic seismic hazard model for southern California
We present a nonergodic framework for probabilistic seismic‐hazard analysis (PSHA) that is constructed entirely of deterministic, physical models. The use of deterministic ground‐motion simulations in PSHA calculations is not new (e.g., CyberShake), but prior studies relied on kinematic rupture generators to extend empirical earthquake rupture...
Milner, Kevin R.; Shaw, Bruce E.; Goulet, Christine A.; Richards-Dinger, Keith B.; Callaghan, Scott; Jordan, Thomas H.; Dieterich, James H.; Field, Edward H.Juvenile Chinook salmon survival, travel time, and floodplain use relative to riverine channels in the Sacramento–San Joaquin River Delta
Floodplains provide multiple benefits to both resident and migratory fish species, including juvenile Chinook Salmon Oncorhynchus tshawytscha, but direct comparisons of survival during migration through a floodplain versus riverine routes are scarce. The Yolo Bypass is a broad floodplain of the Sacramento River that floods in about 30% of...
Pope, Adam; Perry, Russell; Harvey, Brett N.; Hance, Dalton; Hansel, Hal CThe impacts of the 2015/2016 El Niño on California's sandy beaches
The El Niño Southern Oscillation is the most dominant mode of interannual climate variability in the Pacific. The 2015/2016 El Niño event was one of the strongest of the last 145 years, resulting in anomalously high wave energy across the U.S. West Coast, and record coastal erosion for many California beaches. To better manage coastal resources,...
Smith, Schuyler A; Barnard, Patrick L.Characteristics of frequent dynamic triggering of microearthquakes in Southern California
Dynamic triggering of earthquakes has been reported at various fault systems. The triggered earthquakes are thought to be caused either directly by dynamic stress changes due to the passing seismic waves, or indirectly by other nonlinear processes that are initiated by the passing waves. Distinguishing these physical mechanisms is difficult...
Fan, Wenyuan; Barbour, Andrew; Cochran, Elizabeth S.; Lin, GuoqingCharacterizing strain between rigid crustal blocks in the southern Cascadia forearc: Quaternary faults and folds of the northern Sacramento Valley, California
Topographic profiles across late Quaternary surfaces in the northern Sacramento Valley (California, USA) show offset and progressive folding on series of active east- and northeast—trending faults and folds. Optically stimulated luminescence ages on deposits draping a warped late Pleistocene river terrace yielded differential incision rates along...
Angster, Stephen J.; Wesnousky, Steven G.; Figueiredo, Paula; Owen, Lewis A.; Sawyer, ThomasSeismic attenuation monitoring of a critically stressed San Andreas fault
We show that seismic attenuation ( ) along the San Andreas fault (SAF) at Parkfield correlates with the occurrence of moderate‐to‐large earthquakes at local and regional distances. Earthquake‐related anomalies are likely caused by changes in permeability from dilatant static stress changes, damage by strong shaking from local...
Malagnini, Luca; Parsons, Thomas E.Distribution of aseismic deformation along the central San Andreas and Calaveras Faults from differencing repeat airborne lidar
Fault creep reduces seismic hazard and serves as a window into plate boundary processes; however, creep rates are typically constrained with sparse measurements. We use differential lidar topography (11–13 year time span) to measure a spatially dense surface deformation field along a 150 km section of the Central San Andreas and...
Scott, Chelsea P; DeLong, Stephen B.; Arrosmith, J RamonLocalized fault-zone dilatancy and surface inelasticity of the 2019 Ridgecrest earthquakes
Earthquakes produce a spectrum of elastic and inelastic deformation processes that are reflected across various length and time scales. While elasticity has long dominated research assumptions in active tectonics, increasing interest has focused on the inelastic characteristics of earthquakes, particularly those of the surface fault rupture zone...
Barnhart, William D.; Gold, Ryan D.; Hollingsworth, JamesSeismic reflection imaging of the low-angle Panamint normal fault system, eastern California
Shallowly dipping (<30°) low‐angle normal faults (LANFs) have been documented globally; however, examples of active LANFs in continental settings are limited. The western margin of the Panamint Range in eastern California is defined by a LANF that dips west beneath Panamint Valley and has evidence of Quaternary motion. In addition, high‐angle...
Gold, Ryan D.; Stephenson, William J.; Briggs, Richard W.; Duross, Christopher; Kirby, Eric; Woolery, Edward W; Delano, Jaime; Odum, Jackson K.Developing post-alert messaging for ShakeAlert, the earthquake early warning system for the West Coast of the United States of America
As ShakeAlert, the earthquake early warning system for the West Coast of the U.S., begins its transition to operational public alerting, we explore how post-alert messaging might represent system performance. Planned post-alert messaging can provide timely, crucial information to both emergency managers and ShakeAlert operators as well as...
McBride, Sara; Bostrom, Ann; Sutton, Jeannette; deGroot, Robert Michael; Baltay, Annemarie S.; Terbush, Brian; Bodin, Paul; Dixon, Maximilian; Holland, Emily; Arba, Ryan; Laustsen, Paul C.; Liu, Sophia; Vinci, MargaretIncreasing threat of coastal groundwater hazards from sea-level rise in California
Projected sea-level rise will raise coastal water tables, resulting in groundwater hazards that threaten shallow infrastructure and coastal ecosystem resilience. Here we model a range of sea-level rise scenarios to assess the responses of water tables across the diverse topography and climates of the California coast. With 1 m of sea-level rise,...
Befus, K.M.; Barnard, Patrick L.; Hoover, Daniel J.; Finzi Hart, Juliette; Voss, Clifford I.A stress-similarity triggering model for aftershocks of the MW6.4 and MW7.1 Ridgecrest earthquakes
The July 2019 Mw">Mw 6.4 and 7.1 Ridgecrest earthquakes triggered numerous aftershocks, including clusters of off‐fault aftershocks in an extensional stepover of the Garlock fault, near the town of Olancha, and near Panamint Valley. The locations of the off‐fault aftershocks are consistent with the stress‐similarity model of triggering,...
Hardebeck, Jeanne L.The Cliff Feature Delineation Tool scans digital elevation models (DEM) to delineate features on seacliffs like the cliff top, midline, toe, and convexities/concavities on the cliff face, outputting linear features as polylines and point shapefiles.
The MODLFOW One-Water Hydrologic Flow Model (MF-OWHM) (MF-OWHM; Boyce and others, 2020; Hanson and others, 2014) is a MODFLOW-2005-based integrated hydrologic flow model (IHM) that is the most complete version, to date, of the MODFLOW family of hydrologic simulators needed for the analysis of a broad range of conjunctive-use issues.
Use this Groundwater Age Mixtures and Contaminant Trends Tool (GAMACTT) to explore the effects of basic aquifer properties and well configurations on groundwater age mixtures in groundwater discharge and on contaminant trends from varying nonpoint-source contaminant input scenarios.
An Excel® Workbook for Interpreting Groundwater Age Distributions from Environmental Tracer Data
Software to Process and Preserve Legacy Magnetotelluric Data from circa 1990 truck-mounted cross power and time series files in ASCII format.
The Pedestrian Evacuation Analyst is an ArcGIS extension that estimates how long it would take for someone to travel on foot out of a hazardous area that was threatened by a sudden event such as a tsunami, flash flood, or volcanic lahar. It takes into account the elevation changes and the different types of landcover that a person would encounter along the way.
The MODPATH-OBS (Hanson and others, 2013) computer program is designed to calculate simulated equivalents for observations related to advective groundwater transport that can be represented in a quantitative way by using simulated particle-tracking data.
The Central Valley Hydrologic Model (CVHM) is an extensive, detailed three-dimensional (3D) computer model of the hydrologic system of the Central Valley (Faunt, 2009). The Central Valley Hydrologic Model (CVHM) simultaneously accounts for changing water supply and demand across the landscape, and simulates surface water and groundwater flow across the entire Central Valley.
A Grid-Based, Distributed-Parameter Watershed Model to Estimate Net Infiltration Below the Root Zone
Burned, denuded hillside in the CZU Lightning Complex
The USGS landslide team monitors and continues to update the hazard map models based on data collected in burn areas. This information improves future models and provides better hazard assessments used by officials for emergency response and decision making. Many of the steep hillsides burned and denuded in California fires repel water rather than soak it in. This
...Examples of orthomosaic imagery and digital surface model
Examples of orthomosaic imagery and a high-resolution digital surface model of Post Point, Bellingham Bay, WA.
Sampling sediment following wildfires
In August of 2020, the enormous CZU wildfire complex consumed over 85,000 acres in San Mateo and Santa Cruz Counties, leaving scarred landscapes in the hilly region. Runoff from large rainstorms in the winter months carry contaminants from the soils within these burned-out forests. Forest fires and the fire retardants used to help control and extinguish them introduce
...Sampling sediment following wildfires
In August of 2020, the enormous CZU wildfire complex consumed over 85,000 acres in San Mateo and Santa Cruz Counties, leaving scarred landscapes in the hilly region. Runoff from large rainstorms in the winter months carry contaminants from the soils within these burned-out forests. Forest fires and the fire retardants used to help control and extinguish them introduce
...Sampling sediment following wildfires
In August of 2020, the enormous CZU wildfire complex consumed over 85,000 acres in San Mateo and Santa Cruz Counties, leaving scarred landscapes in the hilly region. Runoff from large rainstorms in the winter months carry contaminants from the soils within these burned-out forests. Forest fires and the fire retardants used to help control and extinguish them introduce
...Eagle Rock, California Debris Flow
Rilling and a shallow landslide in CZU Fire near Eagle Rock, California. Soil ~3 cm below surface was almost completely dry after the rain storm, highlighting soil water repellancy.
Big Sur, California Landslide - January 26 and 28, 2021
The storm that hit California’s coast between Jan. 26 and 28, 2021, blew out a portion of Hwy 1 near Big Sur. On Saturday, a USGS reconnaissance flight snapped this dramatic photo above the Rat Creek drainage showing the debris flow.
Rat Creek washout on coastal highway
The atmospheric river, a narrow, powerful track of water vapor that can deliver tremendous volumes of rain, hit the central California coast and stalled there between January 26 and 28, 2021 — with catastrophic consequences. The area around Rat Creek, about 20 miles south of Big Sur's town center,
...Highway 1 washout at Rat Creek
The atmospheric river, a narrow, powerful track of water vapor that can deliver tremendous volumes of rain, hit the central California coast and stalled there between January 26 and 28, 2021 — with catastrophic consequences. The area around Rat Creek, about 20 miles south of Big Sur's town center,
...Steam vents along the Yellowstone River near Mud Volcano thermal area
Steam vents along the Yellowstone River near Mud Volcano thermal area, Yellowstone National Park.
Irrigated Land Use, Adelaida Area, San Luis Obispo County, CA
Irrigated land-use in the Adelaida Area of San Luis Obisbo County, CA for 1984, 1996, 2004, 2014, and 2016. Numbers indicate acres and percent of total acres. Source: California Department of Conservation Farmland Mapping and Monitoring Program,
...Ocean Beach in San Francisco looking north
Ocean Beach in San Francisco looking north

Multimedia documenting coastal change hazards research at the USGS
Southern California can now expect to see post-wildfire landslides occurring almost every year, with major events expected roughly every ten years, a new study led by U.S. Geological Survey researchers finds.

Volunteers contibuted over 300 edits since this challenge was launched last week. This includes the removal of points that are either closed or the wrong feature type. Thank you for helping to update The National Map!

This challenge is now complete! Thank you to everyone who contributed!

TNMCorps Mapping Challenges continue on the Pacific coast with a new challenge for schools in California and Nevada! This is an excellent challenge for Peer Reviewers and Advanced Editors since all the existing points have already been edited, but there are many points needing to be reviewed. Don’t forget to look for missing schools too!

USGS scientists have begun a project to estimate the marine distribution of longfin smelt (Spirinchus thaleichthys) along the North American Pacific coast.

A new geonarrative (Esri Story Map) summarizes the debris flows that were caused by a rainstorm following the Bond Fire in California.

The USGS and State Water Board Oil and Gas Regional Groundwater Monitoring Program are hosting a webinar Friday, February 19 at 10am PT to discuss the scientific findings of the Groundwater Quality of Aquifers Overlying the Oxnard Oil Field, Ventura County, California study.

Volunteers continue to make progress on this challenge as more edits come in!

Summary statistics are now available for this challenge. Thanks again to everyone who contributed!

In the lab, USGS scientists analyze sediment samples collected from stream banks to test for contaminants produced by wildfires. The toxic chemicals can be transported downstream by runoff following rainstorms in the burned regions.

Restoration Assessment and Monitoring Program for the Southwest (RAMPS)
A Program of the Southwest Biological Science Center & Ecosystems Mission Area
To subscribe to our newsletter, please visit: https://listserv.usgs.gov/mailman/listinfo/ramps
--