The California Department of Water Resources (DWR) discrete (vs. continuous) water quality datasets contains DWR-collected, current and historical, chemical and physical parameters found in routine environmental, regulatory compliance monitoring, and special studies throughout the state.

The California Water Boards’ Water Data Center is proud to present the CA Water Quality Status Report. This report is an annual data-driven snapshot of the Water Board's water quality and environmental data. This inaugural version of the report is based solely on the surface water datasets available via the Surface Water Ambient Monitoring Program (SWAMP) and in future years we hope to expand this to include the groundwater, drinking water and water resource datasets available in our state. Our goal is to use data to inform both data storytelling (as in this inaugural report) and water quality indicators, including watershed report cards. The 2017 Water Quality Status Report is organized around seven major themes that our team thought both individually and collectively tell important stories about the overall health of our state’s surface waters. Each theme-specific story includes a brief background, a data analysis summary, an overview of management actions, and access to the raw data. For more information please contact the Office of Information Management and Analysis (OIMA). Data for the section “Setting Flow Targets to Support Biological Integrity in Southern California Streams” can be found on the California open data portal. Data for the section “Nutrients and Algae in Aquatic Ecosystems” can be found here.

Groundwater quality data and related groundwater well information available on the page was queried from the GAMA Groundwater information system (**[GAMA GIS](https://gamagroundwater.waterboards.ca.gov/gama/datadownload)**). Data provided represent a collection of groundwater quality results from various federal, state, and local groundwater sources. Results have been filtered to only represent untreated sampling results for the purpose of characterizing ambient conditions. Data have been standardized across multiple data sets including chemical names and units. Standardization has not been performed for chemical result modifier and others (although we are working currently to standardize most fields). Chemicals that have been standardized are included in the data sets. Therefore, other chemicals have been analyzed for but are not included in GAMA downloads. Groundwater samples have been collected from well types including domestic, irrigation, monitoring, municipal. Wells that cannot accurately be attributed to a category are labeled as "water supply, other". For additional information regarding the GAMA GIS data system please reference our **[factsheet](https://www.waterboards.ca.gov/publications_forms/publications/factsheets/docs/gama_gis_factsheet.pdf)**.

The California Water Quality Status Report is an annual data-driven snapshot of the Water Board’s water quality and ecosystem data. This second edition of the report is organized around the watershed from land to sea. Each theme-specific story includes a brief background, a data analysis summary, an overview of management actions, and access to the raw data. View the 2018 California Water Quality Status Report. Data for Fig. 8 Landscape Constraints on Stream Biological Integrity in the San Gabriel River Watershed can be downloaded from Zenodo. Data for Fig. 13 HAB Incident Reports Map can be downloaded from the California Open Data Portal. For more information please contact the Office of Information Management and Analysis (OIMA).

The California Water Quality Status Report is an annual data-driven snapshot of the Water Board’s water quality and ecosystem data. This third edition of the report is organized around the watershed from land to sea. Each theme-specific story includes a brief background, a data analysis summary, an overview of management actions, and access to the raw data.

View the 2019 California Water Quality Status Report.

• Data for Fig. 2 1,2,3,-Trichloropropane is provided as a download below. The data can also be downloaded from the State Water Resources Control Board (SWRCB) website.
• Data for Fig. 6 Statewide Water Bodies Toxicity can be downloaded from the California Open Data Portal.
• Sediment load data for Fig. 7 Elk River is provided as a download below. Landslide susceptibility data is available on the California Geological Survey GIS server.
• Data for Fig. 8 Central Valley Water Board E. coli Monitoring Results can be downloaded from Google Sheets.
• Data for Fig. 9 Harmful Algal Bloom Incident Reports Map can be downloaded from the California Open Data Portal.
• Data for Fig. 19 Industrial Stormwater Assessment Tool can be downloaded from the California Open Data Portal (Monitoring Data, Facility Information), Office of Environmental Health Hazard Assessment CalEnviroScreen 3.0 webpage, and the SWRCB 2012 Integrated Report webpage.
• Data for Fig. 20 is provided as a download below and is also available on the Stream Quality Index dashboard. Download the file from the dashboard for the most current data.

The California Water Quality Status Report is an annual data-driven snapshot of the Water Board’s water quality and ecosystem data. This third edition of the report is organized around the watershed from land to sea. Each theme-specific story includes a brief background, a data analysis summary, an overview of management actions, and access to the raw data. View the 2019 California Water Quality Status Report. Data for Fig. 2 1,2,3,-Trichloropropane is provided as a download below. The data can also be downloaded from the State Water Resources Control Board (SWRCB) website. Data for Fig. 6 Statewide Water Bodies Toxicity can be downloaded from the California Open Data Portal. Sediment load data for Fig. 7 Elk River is provided as a download below. Landslide susceptibility data is available on the California Geological Survey GIS server. Data for Fig. 8 Central Valley Water Board E. coli Monitoring Results can be downloaded from Google Sheets. Data for Fig. 9 Harmful Algal Bloom Incident Reports Map can be downloaded from the California Open Data Portal. Data for Fig. 19 Industrial Stormwater Assessment Tool can be downloaded from the California Open Data Portal (Monitoring Data, Facility Information), Office of Environmental Health Hazard Assessment CalEnviroScreen 3.0 webpage, and the SWRCB 2012 Integrated Report webpage. Data for Fig. 20 is provided as a download below and is also available on the Stream Quality Index dashboard. Download the file from the dashboard for the most current data.

The Aquifer Risk Map is developed to fulfill requirements of SB-200 (Monning, 2019) and is intended to help prioritize areas where domestic wells and state small water systems may be accessing groundwater that does not meet primary drinking water standards. In accordance with SB-200, the map is made available to the public and updated annually starting January 1, 2021. This application currently displays data from the 2024 Aquifer Risk Map but includes the 2023, 2022, and 2021 maps as archived web pages. The Fund Expenditure Plan states that the risk map will be used by Water Boards staff to help prioritize areas for available SAFER funding.This Web Experience Application displays data from the Aquifer Risk Map and allows users to see different data layers, view the data in spatial and tabular format, and provides links to access related datasets. For more help on how to use the application, click on the question mark under "Map Options".More details about the spatial data layers inside this application are available in the 2024 Aquifer Risk Map Web Map page. A description of how the map layers were created is available in the 2024 Aquifer Risk Map Methodology. The geospatial data is available as a feature service, with a full description on the Portal.If you have questions about the data in this application or questions about how to use this tool, please contact GAMA@waterboards.ca.gov. If you have questions about the SAFER program please contact SAFER@waterboards.ca.gov.

This data release contains site information and potential explanatory factor data for 1,899 groundwater sites. These sites were used to assess groundwater quality in aquifers used for domestic and public drinking water supply in the southeastern San Joaquin Valley. The southeastern San Joaquin Valley (SESJV) study unit consists of five study areas whose boundaries are defined by the eponymous California Department of Water Resources groundwater subbasins of the San Joaquin Valley groundwater basin: Madera-Chowchilla, Kings, Kaweah, Tule, and Tulare Lake. The sites consist of 198 wells representing the domestic-supply aquifer and 1,701 wells representing the public-supply aquifer. The domestic-supply aquifer wells were sampled in 2013-2015 by the USGS for either the California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) or the USGS National Water Quality Assessment project (NAWQA). The public-supply aquifer wells were either sampled by the USGS for the GAMA-PBP in 2005-2018 or have water-quality data in the California State Water Resources Control Board Division of Drinking Water (SWRCB-DDW) public database. The data types in this data release include site identification and location, well construction and lithology data, land use characteristics, groundwater age and oxidation-reduction classifications and aridity indices. Not all sites have data for all fields. Water-quality data for the sites are available from U.S. Geological Survey (2023), and California State Water Resources Control Board Division of Drinking Water (2023). The study design and the assessment results are presented in Burow and others (2024).

Clear Lake is a large, shallow, hypereutrophic lake in Northern California, USA. Clear Lake is an important water resource for the surrounding community offering many cultural and recreational opportunities and provides drinking water for more than half of the region's population. Despite these many ecosystem services, Clear Lake suffers from Harmful Algal Blooms (HABs) of cyanobacteria. This project aims to understand the lake and watershed processes contributing to the negative impacts on the lake water quality and ecosystem health with a goal of rehabilitating the lake. The UC Davis Tahoe Environmental Research Center conducted a 5-year (2019-2023) water quality monitoring program collecting monitoring data to better understand the physical, chemical, and biological processes affecting lake quality. Data from this monitoring program are publicly available here (DOI of EDI data repository to be provided when available). This project is funded by the California Department of Fish and Wildlife through California State Assembly Bill 707 (2017), the California Natural Resources Agency, and the UC Davis Tahoe Environmental Research Center.In addition to this overarching project, we completed additional biological and optical measurements over a shorter 1.5-year time period (Jul 2021 - Oct 2022) with the goal of supporting Phytoplankton Community Composition (PCC) and Cyanobacteria genera differentiation algorithm development from remotely sensed hyperspectral measurements. Three of these sampling events were completed coincident to whole-lake hyperspectral images collected by the DESIS sensor. These additional data included High-Performance Liquid Chromatography (HPLC) phytoplankton pigment data and above-water spectroradiometry (SVC HR-1024i) measurements. This additional work was supported by a NASA Office of STEM Engagement (OSE) graduate student fellowship awarded to Samantha Sharp in 2020 (Grant Number 80NSSC20K1458).

The Division of Drinking Water requires laboratories to submit water quality data directly. The data is received, and published twice monthly on the Division's water quality portal. The resource here now is just a data dictionary for the laboratory analysis data available from that portal, and in the near future we plan to add curated data resources that include laboratory water quality results.

Ontario has a comprehensive set of measures and regulations to help ensure the safety of drinking water.

The following dataset contains information about the drinking water systems, laboratories and facilities the Ministry of the Environment, Conservation and Parks is responsible for monitoring to ensure compliance with Ontario's drinking water laws.

The dataset includes information about:

• the number and type of registered systems and laboratories
• drinking water quality test results
• adverse water quality incidents
• activities to support reduced lead in drinking water
• enforcement activities related to inspections
• orders and convictions
• system operator certification

Long-term freshwater quality data from federal and federal-provincial sampling sites throughout Canada's aquatic ecosystems are included in this dataset. Measurements regularly include physical-chemical parameters such as temperature, pH, alkalinity, major ions, nutrients and metals. Collection includes data from active sites, as well as historical sites that have a period of record suitable for trend analysis. Sampling frequencies vary according to monitoring objectives. The number of sites in the network varies slightly from year-to-year, as sites are adjusted according to a risk-based adaptive management framework. The Great Lakes are sampled on a rotation basis and not all sites are sampled every year. Data are collected to meet federal commitments related to transboundary watersheds (rivers and lakes crossing international, inter-provincial and territorial borders) or under authorities such as the Department of the Environment Act, the Canada Water Act, the Canadian Environmental Protection Act, 1999, the Federal Sustainable Development Strategy, or to meet Canada's commitments under the 1969 Master Agreement on Apportionment.

Field data for vertical water quality profiles using Yellow Spring Instruments (YSI) EXO2 sondes during daylight hours in Clear Lake, Lake County, California. This data release includes all measured environmental parameters included in the analysis. First posted: April 23, 2019 Revised: November 2021

Groundwater quality data and related groundwater well information available on the page was queried from the GAMA Groundwater information system (GAMA GIS). Data provided represent a collection of groundwater quality results from various federal, state, and local groundwater sources. Results have been filtered to only represent untreated sampling results for the purpose of characterizing ambient conditions. Data have been standardized across multiple data sets including chemical names and units. Standardization has not been performed for chemical result modifier and others (although we are working currently to standardize most fields). Chemicals that have been standardized are included in the data sets. Therefore, other chemicals have been analyzed for but are not included in GAMA downloads. Groundwater samples have been collected from well types including domestic, irrigation, monitoring, municipal. Wells that cannot accurately be attributed to a category are labeled as "water supply, other". For additional information regarding the GAMA GIS data system please reference our factsheet.

The dataset documents the spatial and temporal variability of nutrients and related water quality parameters at high spatial resolution in the North Delta, Central Delta, and the Western Delta out to Suisun Bay in the Sacramento-San Joaquin River Delta of California, USA. The dataset includes nitrate, ammonium, phosphate, dissolved organic carbon, temperature, conductivity, dissolved oxygen, and chlorophyll as well as information about phytoplankton community composition. Data-collection cruises were conducted under three different environmental/flow conditions in May, July, and October of 2018. The data release consists of a xml document, 13 text/csv documents, and a zip file. Descriptions for each document and file are listed below: 1. METADATA: (2018_High_resolution_mapping_surveys_v2.0.xml) – Metadata for child item “Assessing spatial variability of nutrients and related water quality constituents in the California Sacramento-San Joaquin Delta at the landscape scale: 2018 High resolution mapping surveys.” 2. QA DATA: (Delta Water Quality Mapping 2018 Data Corrections and Offsets.csv) – Data corrections and offsets calculations applied to the datasets. 3. DATA DICTIONARY (Delta Water Quality Mapping 2018 Data Dictionary v2.0.csv) – Data dictionary for tables and attributes. 4. DISCRETE SAMPLING DATA: (Delta Water Quality Mapping 2018 Discrete Sampling v2.0.csv) – Discrete sampling, water chemistry data from the Sacramento-San Joaquin Delta study area. 5. PHYTOPLANKTON ENUMERATION DATA FROM DISCRETE SAMPLES: (Delta Water Quality Mapping 2018 Discrete Sampling Phytoenumeration v2.0.csv) – Discrete sampling, phytoenumeration data from the Sacramento-San Joaquin Delta study area. 6. May 2018 FIELD MAPPING DATA (High resolution, timestamped and 20 second median filtered): (Delta Water Quality Mapping May 2018 High Resolution.csv) – High resolution, in situ, unfiltered, in vivo fluorescence (IVF), water chemistry data from the Sacramento-San Joaquin Delta study area. All measurements were collected in the field. 7. May 2018 MAPPING DATA ON COMMON SPATIAL FRAMEWORK: (Delta Water Quality Mapping May 2018 Spatially Aligned.csv) – Spatially Aligned (Centerline Extracted) and interpolated, water chemistry data from the Sacramento-San Joaquin Delta study area. 8. July 2018 FIELD MAPPING DATA (High resolution, timestamped and 20 second median filtered): (Delta Water Quality Mapping July 2018 High Resolution.csv) – High resolution, in situ, unfiltered, in vivo fluorescence (IVF), water chemistry data from the Sacramento-San Joaquin Delta study area. All measurements were collected in the field. 9. July 2018 MAPPING DATA ON COMMON SPATIAL FRAMEWORK: (Delta Water Quality Mapping July 2018 Spatially Aligned.csv) – Spatially Aligned (Centerline Extracted) and interpolated, water chemistry data from the Sacramento-San Joaquin Delta study area. 10. FIELD MAPPING DATA (High resolution, timestamped and 20 second median filtered): (Delta Water Quality Mapping October 2018 High Resolution.csv) – High resolution, in situ, unfiltered, in vivo fluorescence (IVF), water chemistry data from the Sacramento-San Joaquin Delta study area. All measurements were collected in the field. 11. October 2018 MAPPING DATA ON COMMON SPATIAL FRAMEWORK: (Delta Water Quality Mapping October 2018 Spatially Aligned.csv) – Spatially Aligned (Centerline Extracted) and interpolated, water chemistry data from the Sacramento-San Joaquin Delta study area. 12. CALCULATED DIFFERENCES BETWEEN MAY AND JULY, 2018: (Delta Water Quality Mapping May to July 2018 Differences.csv) – Calculated differences between months for water chemistry data from the Sacramento-San Joaquin Delta study area. 13. CALCULATED DIFFERENCES BETWEEN MAY AND OCTOBER 2018: (Delta Water Quality Mapping May to October 2018 Differences.csv) – Calculated differences between months for water chemistry data from the Sacramento-San Joaquin Delta study area. 14. CALCULATED DIFFERENCES BETWEEN JULY AND OCTOBER, 2018: (Delta Water Quality Mapping July to October 2018 Differences.csv) – Calculated differences between months for water chemistry data from the Sacramento-San Joaquin Delta study area. 15. SHAPE FILES FOR ALL RESULTS: (Maps_Shapefiles.zip) – Zip file containing 117 shapefiles for spatially aligned water quality constituents from the Sacramento-San Joaquin Delta study area. 16. METHODS: (Methods_ChildItem_v2.0.pdf) – Text document describing methods used for data and sample collection and analysis.

The aquifer risk map is being developed to fulfill requirements of SB-200 and is intended to help prioritize areas where domestic wells and state small water systems may be accessing groundwater that does not meet primary drinking water standards (maximum contaminant level or MCL). In accordance with SB-200, the risk map is to be made available to the public and is to be updated annually starting January 1, 2021. The Fund Expenditure Plan states the risk map will be used by Water Boards staff to help prioritize areas for available SAFER funding.

This layer contains summarized water quality risk per census block group, square mile section, and well point. The overall census block group water quality risk is based on five risk factors (1. the count of chemicals with a long-term average (20 year) or recent result (within 2 years) above the MCL, 2. the count of chemicals with a long-term average (20 year) or recent result (within 2 years) within 80% of the MCL, 3. the average magnitude or results above the MCL, 4. the percent area with chemicals above the MCL, and 5. the percent area with chemicals within 80% of the MCL). The specific chemicals that contribute to these risk factors are listed as well. Higher values for each individual risk factor contribute to a higher overall score. The scores are converted to percentiles to normalize the results. Higher percentiles indicate higher water quality risk. The water quality data is based on depth-filtered, de-clustered water quality results from public and domestic supply wells, collected following a similar methodology as the Domestic Well Needs Assessment White Paper. The methodology used to calculate the risk percentiles is outlined in the Aquifer Risk Map Methodology. To provide comments or feedback on this map, please email SAFER@waterboards.ca.gov or Emily.Houlihan@Waterboards.ca.gov.Methodology for the draft aquifer risk map available for download.

This is a point feature class of environmental monitoring stations maintained in the California Department of Water Resources’ (hereafter the Department) Water Data Library Database (WDL) for discrete “grab” water quality sampling stations. The WDL database contains DWR-collected, current and historical, chemical and physical parameters found in drinking water, groundwater, and surface waters throughout the state. This dataset is comprised of a Stations point feature class and a related “Period of Record by Station and Parameter” table. The Stations point feature class contains basic information about each station including station name, station type, latitude, longitude, and the dates of the first and last sample collection events on record. The related Period of Record Table contains the list of parameters (i.e. chemical analyte or physical parameter) collected at each station along with the start date and end date (period of record) for each parameter and the number of data points collected. The Lab and Field results data associated with this discrete grab water quality stations dataset can be accessed from the California Natural Resources Agencies Open Data Platform at https://data.cnra.ca.gov/dataset/water-quality-data or from DWR’s Water Data Library web application at https://wdl.water.ca.gov/waterdatalibrary/index.cfm.

Groundwater arsenic concentrations in the San Joaquin Valley have varied over the decades from 1980 to 2019. This report was compiled to determine whether arsenic concentrations are increasing or decreasing and the mechanism controlling the trends. The San Joaquin Valley contains 4,979 wells with arsenic analyses and possible co-detections of any of the following constituents: dissolved oxygen, field-measured pH, iron, manganese, sulfate, nitrate, or water level. Water quality data comes from two sources: 3,302 wells from with California State Water Resources Control Board - Division of Drinking Water and 1,448 wells from the U.S. Geological Survey National Water Information System (California State Water Resources Control Board – Division of Drinking Water, 2019; U.S. Geological Survey, 2020). There are an additional 229 wells with data from both sources. Other data compiled in addition to the constituents analysed are well type, water use, status, and depth. Well location in rel ...

Historical water quality data measured on a continuous basis at over 23 locations across Canada is included in this dataset. Most locations include hourly temperature, dissolved oxygen, pH, specific conductance and turbidity. Data are collected by Environment and Climate Change Canada (ECCC) and in partnership with other federal departments and provinces and territories to enable the detection of short-term water quality events, and to determine trends in water quality, especially at transboundary sites (or Federal waters) in support of Federal legislation and international agreements, or to report on the status of Government of Canada priority aquatic ecosystems.

This dataset looks at all aspects of storm water management in California as managed and regulated by the State Water Resources Control Board, from the Stormwater Multiple Application and Report Tracking System (SMARTS).