Data and Databases - Open Data and Maps

open data maps

This topic provides links to sources of open data, which is defined as data that are freely available, machine-readable, and formatted according to national technical standards to facilitate visibility and re-use of published data (see the U.S. Federal Government's Project Open Data for a more complete definition of the principles of open data). It also provides links to maps that cover a wide range of Water Board programs and describe the beneficial uses they protect and restore.

Open Water Data

California Open Data Portal – Water Data
A subset of the datasets maintained by the Water Boards can be found on the State of California's Open Data Portal under the 'Water' category. That platform provides web services that enhance data accessibility, and we plan to continue adding datasets to that platform in the future. Note that the datasets found on that site mirror some of the datasets provided through this Water Boards portal.

National Water Quality Monitoring Council's Water Quality Portal
The National Water Quality Monitoring Council maintains a data portal housing water quality information from over 400 state, federal, tribal, and local agencies. It is a cooperative service sponsored by the United States Geological Survey (USGS), the Environmental Protection Agency (EPA), and the National Water Quality Monitoring Council (NWQMC).


Data Maps
Maps that cover a wide range of Water Boards programs and the beneficial uses they protect and restore.

GIS Specific Web Services

Map Services
Map services for the spatial data provided by many of the Water Boards’ map applications are open and available for public developer use via our GIS server endpoint. Map services are generally provided in ESRI REST, OGC WMS and KML formats. For questions regarding the use of the map services, please contact

Flat Files

Flat files contain data that is only linked to a column and a row, and do not contain any other internal hierarchy or structure that pre-defines relationships between the data points. Flat files are important because they provide data in a file format that can be easily accessed and manipulated without the need of special software or technical skill, so they serve to make data more open and transparent.

  • NPDES Permits (including Stormwater) (Excel)
    This Excel spreadsheet lists NPDES permits, including storm water general permit enrollees that are active or have been active within the past three years. The facility and discharger addresses are also provided. Please note there can be multiple listings for a single permit due to multiple dischargers, multiple facilities, and/or multiple address listings. Because the Regulatory Measure ID (column E) is a unique identifier for each permit, this number can be used to evaluate whether a particular permit is listed more than once. For assistance, please contact the CIWQS Help Center at or 866-792-4977.
  • Monthly Conservation Reporting Archive
    This page provides links Excel workbooks containing urban water supplier reports and cumulative savings and compliance datasets, which are updated monthly. Scroll to the heading labeled ‘Monthly Reporting Archive’ and click on the most recent month to download the most recent dataset.
  • Drinking Water Program Repository
    This page provides links to download flat files (CSV files and Excel workbooks) containing data covering a number of categories within the drinking water program, including annual reports from public water systems, a list of active public water systems (including contact, location, water source, and type), recent conservation reports for small water suppliers and urban water suppliers, and drinking water quality results from 2013 to present. For assistance, please contact the DRINC portal administrator at
  • Sanitary Sewer Overflow Reduction Program Data
    This dataset contains information about any overflow, spill, release, discharge or diversion of untreated or partially treated wastewater from a sanitary sewer system. SSOs include: overflows or releases of untreated or partially treated wastewater that reach waters of the United States; overflows or releases of untreated or partially treated wastewater that do not reach waters of the United States; and wastewater backups into buildings and on private property that are caused by blockages or flow conditions within the publicly owned portion of a sanitary sewer system.
Other Resources

Some Water Boards' databases have reporting systems that allow users to directly access a specified URL to retrieve an up-to-date version of a data query, returned as either as a webpage or Excel workbook. For example, as part of the Regulated Facility Report from the CIWQS database, the query at this link will open a list of state owned wastewater treatment facilities on a webpage, and this link will open an Excel-based version of the same report. Some other examples of CIWQS reports with this feature are the are Facility At-a-Glance Report and the Mandatory Minimum Penalty Report (note that you must select criteria, run the report, and in some cases drill-down in order to copy an identifying URL).