USGS California Streamflow Map

Navigating California’s Water Systems with the USGS Interactive State Map

The USGS State Map serves as a primary navigation portal for California’s vast hydrological network. This tool allows users to visually locate and select specific stream gages to access site-specific data, using a color-coded system to show how current levels rank against history.

The USGS WaterWatch Streamflow Map (identified as the State Map on the main dashboard) provides a visual representation of real-time streamflow compared to historical data for a specific day of the year.

Key Features and Functionality

This interactive viewer for California streamflow data allows users to click on individual gauging stations to access detailed site pages. The interface includes search functionality and zoom controls to navigate the state's hydrological network.

Real-Time Data Comparison: The map displays streamgage locations across California, showing how current water levels compare to historical records for this date.
Interactive Navigation: Users can click on any individual streamgage (colored dot) on the map to navigate to a dedicated page for that specific site.
Search and Filter Tools:
- Map Type: A dropdown menu allows users to switch between different data views, such as "Real-Time".
- Region Selection: Users can filter the map by state (e.g., California) or by Water Resource Region.
- Search Box: A search bar at the top right of the map enables quick location of specific USGS streamgages.
- Zoom/Pan Controls: Standard map navigation tools are located on the left side of the map interface.

Understanding the Map Legend (Percentile Classes)

The streamgages are color-coded based on their flow percentiles, indicating how the current flow compares to historical norms:

Black: High
Dark Blue (>90): Much above normal
Light Blue (76–90): Above normal
Green (25–75): Normal
Orange (10–24): Below normal
Dark Red (<10): Much below normal
Red: Low
White Circle: Not-ranked

Learn More About Tracking California Water Levels

Use the guides below to navigate the various tools and data visualizations provided by the USGS. These resources are designed to help you interpret real-time streamflow maps, historical runoff comparisons, and regional water conditions across California.