This data includes information on water quality, zooplankton, and fish sampled in ponds on delta islands in San Joaquin County, California. The islands include Bacon (North and South ponds), Bouldin (East and West ponds), Holland Tract (Middle, North, and South ponds), and Webb Tract (East, Middle, and North ponds). Discrete water quality parameters were measured bimonthly and continuous temperature was recorded every 15 minutes. Zooplankton were sampled monthly using a Schindler-Patalas 12L plankton trap with a 200mL Dolphin bucket with 61 micron stainless mesh. Fish were sampled once at each pond using beach seines, gill nets, and boat electrofishing gear.

This data release includes water quality and zooplankton data collected from ponds on Boudin Island in the Sacramento-San Joaquin Delta. Data were collected in the Bouldin East and Bouldin West ponds concurrently with a Delta Smelt Deployment Experiment which involved three cages in each pond with approximately 60 Delta Smelt (Hypomesus transpacificus) in each cage. There were two fish deployments, the first deployment was from 11/21/2022 to 01/04/2023 (~6 weeks) and the second was from 02/02/2023 to 05/03/2023 (~13 weeks). Temperature, dissolved oxygen, turbidity, specific conductance, salinity, chlorophyll, and pH were measured weekly. Water temperature was recorded continuously (15-minute sampling interval). Zooplankton were sampled weekly using a Schindler-Patalas 12L plankton trap with a 200mL Dolphin bucket with 61 micron stainless mesh. Water quality measurements and zooplankton samples were collected at a fixed station approximately 50 m from the cages. Additional discrete water quality measurements and zooplankton samples were collected inside the cages at week 0 and 3 during the first deployment and week 0, 3, and 12 during the second deployment.

This data release includes water quality and zooplankton data collected from ponds on Boudin Island in the Sacramento-San Joaquin Delta. Data were collected in the Bouldin East and Bouldin West ponds concurrently with a Delta Smelt Deployment Experiment which involved three cages in each pond with approximately 60 Delta Smelt (Hypomesus transpacificus) in each cage. There were two fish deployments, the first deployment was from 11/21/2022 to 01/04/2023 (~6 weeks) and the second was from 02/02/2023 to 05/03/2023 (~13 weeks). Temperature, dissolved oxygen, turbidity, specific conductance, salinity, chlorophyll, and pH were measured weekly. Water temperature was recorded continuously (15-minute sampling interval). Zooplankton were sampled weekly using a Schindler-Patalas 12L plankton trap with a 200mL Dolphin bucket with 61 micron stainless mesh. Water quality measurements and zooplankton samples were collected at a fixed station approximately 50 m from the cages. Additional discrete water quality measurements and zooplankton samples were collected inside the cages at week 0 and 3 during the first deployment and week 0, 3, and 12 during the second deployment.

This data release includes water quality and zooplankton data collected concurrently with the Floating Wetland Experiment in the West Pond on Bouldin Island in the Sacramento-San Joaquin Delta. Data were collected to monitor water quality and zooplankton community composition before and after the installation of a floating tule wetland. The data were collected at a site near the floating wetland in the northern region and away from the wetland in the southeast region of the pond. There were four cages deployed at both sites with approximately 60 Delta Smelt (Hypomesus transpacificus) in each cage. Water quality and zooplankton samples were collected on six days between 1/30/2024 and 04/30/2024, the floating wetland was installed on 03/08/2024, and the cages with fish were deployed on 03/15/2024. Discrete water quality measurements included temperature, dissolved oxygen, turbidity, specific conductance, salinity, chlorophyll, and pH. Water samples were also collected and analyzed by the National Water Quality Laboratory for dissolved organic carbon, total particulate carbon, total particulate nitrogen, particulate inorganic carbon, and particulate organic carbon. Zooplankton were sampled using a Schindler-Patalas 12 liters (L) plankton trap with a 200 milliliters (mL) Dolphin bucket with 61 micron stainless mesh.

In the spring of 2003, California Department of Fish and Game (CDFG) personnel began quarterly sampling of Salton Sea fish at fourteen stations around the sea, as the basis of a long term monitoring program. In conjunction with this effort, water quality sampling takes place at the same time and place. *Note: This dataset should be viewed with the Quarterly Fishery Surveys - Salton Sea [ds428] dataset. Methods: Eleven sampling sites comprise three broad habitat types: pelagic (3 sites), near-shore (8 sites), and estuarine (3 sites). The pelagic sites are in the approximate middles of the north basin, south basin and inter-basin areas of the Sea. The near-shore sites are spaced widely apart, four each, near the west and east shores, to capture as much breadth of habitat as possible. The estuarine sites are in the body of the Sea, close enough to the mouths of the New, Alamo, and Whitewater Rivers, to be under the influence of their outflows. The three deep water (pelagic) sites were completely unproductive for gill net sampling of fish during the first year of sampling. They have subsequently been dropped from the sampling protocol. Sampling takes place during each of the putative seasons, as follows: spring- April and May; summer- July and August; fall- October and November; winter- January and February. We attempt to compress the total sampling period into as few days as possible, to the extent that the weather, equipment maintenance, and personnel scheduling constraints allow. Nets are set for a 24 hour period. At the time of each set and retrieval of nets, water temperature, conductivity, specific conductivity, dissolved oxygen and sampling depth are measured and recorded, at the approximate mid-net water depth. Measurements are made with a handheld YSI meter, Model 85. Salinity is calculated from the specific conductivity measurement using the following algorithm: Salinity = 0.013(SC2) - 0.233(SC) + 17.102

In the spring of 2003, California Department of Fish and Game (CDFG) personnel began quarterly sampling of Salton Sea fish at fourteen stations around the sea, as the basis of a long term monitoring program. In conjunction with this effort, water quality sampling takes place at the same time and place. *Note: This dataset should be viewed with the Quarterly Fishery Surveys - Salton Sea [ds428] dataset. Methods: Eleven sampling sites comprise three broad habitat types: pelagic (3 sites), near-shore (8 sites), and estuarine (3 sites). The pelagic sites are in the approximate middles of the north basin, south basin and inter-basin areas of the Sea. The near-shore sites are spaced widely apart, four each, near the west and east shores, to capture as much breadth of habitat as possible. The estuarine sites are in the body of the Sea, close enough to the mouths of the New, Alamo, and Whitewater Rivers, to be under the influence of their outflows. The three deep water (pelagic) sites were completely unproductive for gill net sampling of fish during the first year of sampling. They have subsequently been dropped from the sampling protocol. Sampling takes place during each of the putative seasons, as follows: spring- April and May; summer- July and August; fall- October and November; winter- January and February. We attempt to compress the total sampling period into as few days as possible, to the extent that the weather, equipment maintenance, and personnel scheduling constraints allow. Nets are set for a 24 hour period. At the time of each set and retrieval of nets, water temperature, conductivity, specific conductivity, dissolved oxygen and sampling depth are measured and recorded, at the approximate mid-net water depth. Measurements are made with a handheld YSI meter, Model 85. Salinity is calculated from the specific conductivity measurement using the following algorithm: Salinity = 0.013(SC2) - 0.233(SC) + 17.102

In the spring of 2003, California Department of Fish and Game (CDFG) personnel began quarterly sampling of Salton Sea fish at fourteen stations around the sea, as the basis of a long term monitoring program. In conjunction with this effort, water quality sampling takes place at the same time and place. *Note: This dataset should be viewed with the Quarterly Fishery Surveys - Salton Sea [ds428] dataset. Methods: Eleven sampling sites comprise three broad habitat types: pelagic (3 sites), near-shore (8 sites), and estuarine (3 sites). The pelagic sites are in the approximate middles of the north basin, south basin and inter-basin areas of the Sea. The near-shore sites are spaced widely apart, four each, near the west and east shores, to capture as much breadth of habitat as possible. The estuarine sites are in the body of the Sea, close enough to the mouths of the New, Alamo, and Whitewater Rivers, to be under the influence of their outflows. The three deep water (pelagic) sites were completely unproductive for gill net sampling of fish during the first year of sampling. They have subsequently been dropped from the sampling protocol. Sampling takes place during each of the putative seasons, as follows: spring- April and May; summer- July and August; fall- October and November; winter- January and February. We attempt to compress the total sampling period into as few days as possible, to the extent that the weather, equipment maintenance, and personnel scheduling constraints allow. Nets are set for a 24 hour period. At the time of each set and retrieval of nets, water temperature, conductivity, specific conductivity, dissolved oxygen and sampling depth are measured and recorded, at the approximate mid-net water depth. Measurements are made with a handheld YSI meter, Model 85. Salinity is calculated from the specific conductivity measurement using the following algorithm: Salinity = 0.013(SC2) - 0.233(SC) + 17.102

This data release documents the spatial and temporal variability of nutrients and related water quality parameters at high spatial resolution in the western and central portion of the Sacramento-San Joaquin River Delta of California, USA. The data set includes water residence time, nitrate, ammonium, phosphate, dissolved organic carbon, temperature, conductivity, dissolved oxygen, turbidity, and chlorophyll. Data collection were conducted over six days between August 2015 - July 2016 to document conditions prior to, during, and following the installation of a rock barrier on False Barrier to limit salt intrusion.

Broad-area, high-resolution, boat-based water quality mapping surveys of the Sacramento-San Joaquin Delta and Suisun Bay (Delta) of California, USA were conducted under different environmental/flow conditions in May, July, and October of 2023. The spatial and temporal variability of nutrients, phytoplankton, and related water quality parameters were assessed. This dataset includes measurements of nitrate, ammonium, orthophosphate, dissolved organic carbon, temperature, conductivity, dissolved oxygen, and chlorophyll.