Tools and Products


Natural Flows Database

The Nature Conservancy and partners have generated estimates of natural flows (expected streamflow in the absence of human modification) in all the streams and rivers in California. Two datasets are available: 1) natural functional flow metrics to support the California Environmental Flows Framework and 2) monthly natural flows from 1950-2021. Data can be queried directly using an API or visualized and downloaded with a map-based application that allows the user to search for stream segments and download flow data from an intuitive graphical user interface. Access the Natural Flows Database here.

The Natural Flows Database.

Functional Flows Calculator

The Functional Flows Calculator (FFC) quantifies functional flow metrics from a hydrologic time series. It can be accessed on the eflows website, which includes tools for visualizing, downloading, and exploring California's unimpaired streamflow patterns, including natural stream classes, dimensionless reference hydrographs, and functional flow metrics. Reference hydrology at USGS reference gages throughout the state can also be explored on the eflows website. Access the eflows website here Create an account on the website to upload your gage data and calculate functional flow metrics. To access the FFC, click on the "upload data" button on the bottom of the page.

The Functional Flows Calculator.

R Package for Obtaining Functional Flow Metrics

An R package has been developed that allows users to access the Functional Flows Calculator directly via an API. The package allows users to:

  • Retrieve streamflow data automatically from USGS or transform user-uploaded streamflow timeseries and run them through the functional flow calculator online,
  • Obtain modeled functional flow metrics for a stream reach (NHD COMID) of interest,
  • Create plots of dimensionless hydrographs using input flow data, and
  • Compare observed and natural functional flow metrics to assess flow alteration at a given location.

The package is available on GitHub.

Umbrella Species and Functional Flow Needs

Umbrella fish species and their functional flow requirements were identified for California. Access the map here, or begin using the map below by clicking "OK". The map displays the umbrella species for California; users may click on a watershed to view regional fish species assemblages (where each assemblage is represented by a different color), the umbrella species associated with each assemblage, and the HUC 12 distributions that comprise these assemblages outlined in gray. Functional flow needs for each umbrella species are available in the attached Excel workbook. For further details on how umbrella species were identified, see Obester et al. 2021.