Discrete water quality monitoring data from the Sacramento-San Joaquin Bay-Delta collected by the Environmental Monitoring Program. Data is also accessible via the [Environmental Data Initiative](https://portal.edirepository.org/nis/mapbrowse?scope=edi&identifier=458&revision=10).

The goal of this study was to develop a suite of inter-related water quality monitoring approaches capable of modeling and estimating the spatial and temporal gradients of particulate and dissolved total mercury (THg) concentration, and particulate and dissolved methyl mercury (MeHg), concentration, in surface waters across the Sacramento / San Joaquin River Delta (SSJRD). This suite of monitoring approaches included: a) data collection at fixed continuous monitoring stations (CMS) outfitted with in-situ sensors, b) spatial mapping using boat-mounted flow-through sensors, and c) satellite-based remote sensing. The focus of this specific child page is to document the temporal high-resolution (15 minute) in-situ sensor data collected at the four primary CMS locations. The four primary CMS locations chosen for this study included: a) a Sacramento R. dominated site in the northern portion of the Delta (Freeport, FPT, USGS Station_no. 11447650); b) a site in western portion of the central Delta, which is associated with the Cache Slough Complex and is seasonally influenced by the Yolo Bypass when it flows (Liberty Island, LIB, USGS Station_no. 11455315); c) a site in the southern reach of the central Delta where the Sacramento and San Joaquin Rivers have strong seasonal influences on water quality (Middle River, MDM, USGS Station_no. 11312676); and d) a site in the eastern central Delta where the Sacramento, Cosumnes, and Mokelumne rivers have strong seasonal influences on water quality (Little Potato Slough, LPS, USGS Station_no. 11336790). These four sites were used for monitoring of optical properties and hydrodynamics at high frequency (15 minute) intervals over the 2-year study period. Specifically, the data collected at each site includes tidal stage; velocity; nitrate measured via absorbance spectrometry (SUNA V2, Seabird Inc); and optical measurements of turbidity, chlorophyll-a fluorescence, and fluorescent dissolved organic matter, all measured via deployable multiparameter sonde (YSI EXO2, Yellow Springs, Inc). The time series data for all four CMS sites was downloaded for the 2-year period of record (July 1, 2019 through July 1, 2021) from the USGS National Water Information System (NWIS) website (https://waterdata.usgs.gov/nwis), and are presented here in a single machine-readable datafile (CMS_TimeSeries_Data.csv), which includes data for all of the parameters described above. In certain situations, specific sensors were not operational at a given site for a particular time period, and thus the associated water-quality data are not provided as part of the time series record in those instances. These high frequency temporal records provide the explanatory variables used to modeled THg and MeHg concentrations over time and at high temporal frequency throughout the SSJRD.

The goal of this study was to develop a suite of inter-related water quality monitoring approaches capable of modeling and estimating the spatial and temporal gradients of particulate and dissolved total mercury (THg) concentration, and particulate and dissolved methyl mercury (MeHg), concentration, in surface waters across the Sacramento / San Joaquin River Delta (SSJRD). This suite of monitoring approaches included: a) data collection at fixed continuous monitoring stations (CMS) outfitted with in-situ sensors, b) spatial mapping using boat-mounted flow-through sensors, and c) satellite-based remote sensing. The focus of this specific child page is to document the temporal high-resolution (15 minute) in-situ sensor data collected at the four primary CMS locations. The four primary CMS locations chosen for this study included: a) a Sacramento R. dominated site in the northern portion of the Delta (Freeport, FPT, USGS Station_no. 11447650); b) a site in western portion of the central Delta, which is associated with the Cache Slough Complex and is seasonally influenced by the Yolo Bypass when it flows (Liberty Island, LIB, USGS Station_no. 11455315); c) a site in the southern reach of the central Delta where the Sacramento and San Joaquin Rivers have strong seasonal influences on water quality (Middle River, MDM, USGS Station_no. 11312676); and d) a site in the eastern central Delta where the Sacramento, Cosumnes, and Mokelumne rivers have strong seasonal influences on water quality (Little Potato Slough, LPS, USGS Station_no. 11336790). These four sites were used for monitoring of optical properties and hydrodynamics at high frequency (15 minute) intervals over the 2-year study period. Specifically, the data collected at each site includes tidal stage; velocity; nitrate measured via absorbance spectrometry (SUNA V2, Seabird Inc); and optical measurements of turbidity, chlorophyll-a fluorescence, and fluorescent dissolved organic matter, all measured via deployable multiparameter sonde (YSI EXO2, Yellow Springs, Inc). The time series data for all four CMS sites was downloaded for the 2-year period of record (July 1, 2019 through July 1, 2021) from the USGS National Water Information System (NWIS) website (https://waterdata.usgs.gov/nwis), and are presented here in a single machine-readable datafile (CMS_TimeSeries_Data.csv), which includes data for all of the parameters described above. In certain situations, specific sensors were not operational at a given site for a particular time period, and thus the associated water-quality data are not provided as part of the time series record in those instances. These high frequency temporal records provide the explanatory variables used to modeled THg and MeHg concentrations over time and at high temporal frequency throughout the SSJRD.

The Interagency Ecological Program’s (IEP) Environmental Monitoring Program (EMP) was initiated in compliance with the Water Right Decision D-1379 (now mandated by Water Right Decision D-1641) and has monitored discrete water quality and nutrients in the upper San Francisco Estuary since 1975. The objectives of the EMP are to obtain consistent and accurate monthly data at established monitoring stations, provide and document information necessary to achieve compliance with salinity, flow, and dissolved oxygen standards, and to report this information for the purpose of management and conservation of the upper San Francisco Estuary. While the EMP also collects biological data, this dataset only includes the discrete water quality and nutrient data collected by the EMP from 1975-2021. Links to other EMP datasets can be found [here](https://emp-dwr.github.io/emp-website/qmd-files/website/general/data-links.html). Data is also accessible via the [Environmental Data Initiative](https://portal.edirepository.org/nis/mapbrowse?scope=edi&identifier=458&revision=12).

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 http://wdl.water.ca.gov/waterdatalibrary/index.cfm.

The Surface Water Ambient Monitoring Program (SWAMP) mission is to provide resource managers, decision makers, and the public with timely, high-quality information to evaluate the condition of all waters throughout California. SWAMP accomplishes this through carefully designed, externally reviewed monitoring programs, and by assisting other entities state-wide in the generation of comparable data that can be brought together in integrated assessments that provide answers to current management questions. https://www.waterboards.ca.gov/water_issues/programs/swamp/ *These datasets are provisional and subject to revision. They should not be used for regulatory purposes.

This data provides results from field analyses, from the California Environmental Data Exchange Network (CEDEN). The data set contains two provisionally assigned values (“DataQuality” and “DataQualityIndicator”) to help users interpret the data quality metadata provided with the associated result. Due to file size limitations, the data has been split into individual resources by year. The entire dataset can also be downloaded in bulk using the zip files on this page (in csv format or parquet format), and developers can also use the API associated with each year's dataset to access the data. Example R code using the API to access data across all years can be found [here](https://gist.github.com/daltare/2de1517ad1e315c4b1cad01278de96dd). Users who want to manually download more specific subsets of the data can also use the CEDEN query tool, at: https://ceden.waterboards.ca.gov/AdvancedQueryTool

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 http://wdl.water.ca.gov/waterdatalibrary/index.cfm.

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 http://wdl.water.ca.gov/waterdatalibrary/index.cfm.

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.