North Kings Groundwater Sustainability Groundwater Sustainability Plan

North Kings Groundwater Sustainability Agency | November 21st, 2019

North San Francisco Bay Shallow Aquifer Study Unit, 2012: California GAMA Priority Basin Project

U.S. Geological Survey (USGS) | July 20th, 2017

Groundwater quality in the North San Francisco Bay Shallow Aquifer study unit (NSF-SA) was investigated as part of the Priority Basin Project of the California

Groundwater quality in the North San Francisco Bay Shallow Aquifer study unit (NSF-SA) was investigated as part of the Priority Basin Project of the California Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study unit is in Marin, Mendocino, Napa, Solano, and Sonoma Counties and included two physiographic study areas: the Valleys and Plains area and the surrounding Highlands area. The NSF-SA focused on groundwater resources used for domestic drinking water supply, which generally correspond to shallower parts of aquifer systems than that of groundwater resources used for public drinking water supply in the same area. The assessments characterized the quality of untreated groundwater, not the quality of drinking water. This study included three components: (1) a status assessment, which characterized the status of the quality of the groundwater resources used for domestic supply for 2012; (2) an understanding assessment, which evaluated the natural and human factors potentially affecting water quality in those resources; and (3) a comparison between the groundwater resources used for domestic supply and those used for public supply.

North San Francisco Bay Shallow Aquifer Study Unit, 2012: California GAMA Priority Basin Project (Version 1.1, February 2018)

U.S. Geological Survey (USGS) | February 23rd, 2018

Groundwater quality in the North San Francisco Bay Shallow Aquifer study unit (NSF-SA) was investigated as part of the Priority Basin Project of the California Grou

Groundwater quality in the North San Francisco Bay Shallow Aquifer study unit (NSF-SA) was investigated as part of the Priority Basin Project of the California Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study unit is in Marin, Mendocino, Napa, Solano, and Sonoma Counties and included two physiographic study areas: the Valleys and Plains area and the surrounding Highlands area. The NSF-SA focused on groundwater resources used for domestic drinking water supply, which generally correspond to shallower parts of aquifer systems than that of groundwater resources used for public drinking water supply in the same area. The assessments characterized the quality of untreated groundwater, not the quality of drinking water. This study included three components: (1) a status assessment, which characterized the status of the quality of the groundwater resources used for domestic supply for 2012; (2) an understanding assessment, which evaluated the natural and human factors potentially affecting water quality in those resources; and (3) a comparison between the groundwater resources used for domestic supply and those used for public supply. The status assessment was based on data collected from 71 sites sampled by the U.S. Geological Survey for the GAMA Priority Basin Project in 2012. To provide context, concentrations of constituents measured in groundwater were compared to U.S. Environmental Protection Agency (EPA) and California State Water Resources Control Board Division of Drinking Water regulatory and non-regulatory benchmarks for drinking-water quality. The status assessment used a grid-based method to estimate the proportion of the groundwater resources that has concentrations of water-quality constituents approaching or above benchmark concentrations. This method provides statistically unbiased results at the study-area scale and permits comparisons to other GAMA Priority Basin Project study areas. In the NSF-SA study unit as a whole, inorganic constituents with human-health benchmarks were detected at high relative concentrations (RCs) in 27 percent of the shallow aquifer system, and inorganic constituents with secondary maximum contaminant levels (SMCL) were detected at high RCs in 24 percent of the system. The inorganic constituents detected at high RCs were arsenic, boron, fluoride, manganese, nitrate, iron, sulfate, and total dissolved solids (TDS). Organic constituents with human-health benchmarks were detected at high RCs in 1 percent of the shallow aquifer system. Of the 148 organic constituents analyzed, 30 constituents were detected, although only 1, chloroform, had a detection frequency greater than 10 percent. Natural and anthropogenic factors that could affect the groundwater quality were evaluated by using results from statistical testing of associations between constituent concentrations and values of potential explanatory factors. Groundwater age class (modern, mixed, or pre-modern), redox class (oxic or anoxic), aquifer lithology class (metamorphic, sedimentary, or volcanic), and dissolved oxygen concentrations were the explanatory factors that explained distribution patterns of most of the inorganic constituents best. Groundwater classified primarily as pre-modern or mixed in age was associated with higher concentrations of arsenic and fluoride than waters classified as modern. Anoxic or mixed redox conditions were associated with higher concentrations of boron, fluoride, and manganese. Similar patterns of association with explanatory variables were seen for inorganic constituents with aesthetic-based benchmarks detected at high concentrations. Nitrate and perchlorate had higher concentrations in oxic than in the anoxic redox class and were positively correlated with urban land use. The NSF-SA water-quality results were compared to those of the GAMA North San Francisco Bay Public-Supply Aquifer study unit (NSF-PA). The NSF-PA was sampled in 2004 and covers much of the same area as the NSF-SA, but focused on the deeper public-supply aquifer system. The comparison of the NSF-PA to the NSF-SA showed that there were more differences between the Valleys and Plains study areas of the two study units than between the Highlands study areas of the two study units. As expected from the shallower depth of wells, the NSF-SA Valleys and Plains study area had a lesser proportion of pre-modern age groundwater and greater proportion of modern age groundwater than the NSF-PA Valleys and Plains study area. In contrast, well depths and groundwater ages were not significantly different between the two Highlands study areas. Arsenic, manganese, and nitrate were present at high RCs, and perchlorate was detected in greater proportions of the NSF-SA Valleys and Plains study area than the NSF-PA Valleys and Plains study area.

Not All Rivers Are Created Equal: The Importance of Spring-Fed Rivers under a Changing Climate

Water (MDPI) | June 12th, 2021

In the Western United States, volcanic spring-fed rivers are anticipated to become increasingly more important for salmonids and other native fishes, as these rivers wil

In the Western United States, volcanic spring-fed rivers are anticipated to become increasingly more important for salmonids and other native fishes, as these rivers will retain cold-water habitats as the climate warms. Despite this, little is known about the hydro-biogeochemical interactions within these ecosystems. A review of existing literature on spring-fed rivers, coupled with a decade of research on volcanic spring-fed rivers of northern California, finds that these systems are exceptionally productive and exhibit stable environmental conditions. These unique conditions stem from hydrogeologic processes typical of young volcanic terrains. Aquatic macrophytes, common to some nutrient-rich spring-fed systems, play a disproportionate role in hydrologic and geomorphic processes by facilitating ecological interactions and velocity conditions that improve juvenile salmonid growth. We find that volcanic spring-fed rivers are also resilient to climate change, due not only to their ability to dampen water temperature changes through deep groundwater flow but also because of their nutrient-driven high ecosystem productivity, which may enable cold-water species to metabolically compensate for marginal increases in water temperature. Understanding the fundamental geomorphic and ecological differences between these rare ecosystems and their numerically dominant runoff rivers is essential for developing long-term conservation strategies for cold-water species under a rapidly changing climate.

Nutrient Chemistry in the Elizabeth Lake Subwatershed: Effects of Onsite Wastewater Treatment Systems on Groundwater and Lake Water Quality, Los Angeles County, California

U.S. Geological Survey (USGS) | April 16th, 2024

Nutrient (nitrogen [N] and phosphorus [P] chemistry) down-gradient from onsite wastewater treatment system (OWTS) was evaluated with a groundwater study in the area surr

Nutrient (nitrogen [N] and phosphorus [P] chemistry) down-gradient from onsite wastewater treatment system (OWTS) was evaluated with a groundwater study in the area surrounding Elizabeth Lake, the largest of three sag lakes within the Santa Clara River watershed of Los Angeles County, California. Elizabeth Lake is listed on the “303 (d) Impaired Waters List” for excess nutrients and is down-gradient from more than 600 OWTS. The primary objective of this study was to develop a conceptual hydrogeological model to determine if discharge from OWTS is transported into shallow groundwater within the Elizabeth Lake subwatershed and contributes nutrients to Elizabeth Lake in excess of the total maximum daily load limit.

Nutrient Dynamics of the Delta: Effects on Primary Producers

University of California, Davis (UC Davis) | December 1st, 2016

Increasing clarity of Delta waters, the emergence of harmful algal blooms, the growth of aquatic water weeds, and the altered food web of the Delta have recently brought

Increasing clarity of Delta waters, the emergence of harmful algal blooms, the growth of aquatic water weeds, and the altered food web of the Delta have recently brought nutrient dynamics to the forefront. This paper focuses on the sources of nutrients, the transformation and uptake of nutrients, and the links of nutrients to primary producers. The largest loads of nutrients to the Delta come from the Sacramento River with the San Joaquin River seasonally important, especially in the summer. Light regime, grazing pressure, and nutrient availability influence rates of primary production at different times and locations within the Delta. Modern sensor technology and networks are now deployed that make high frequency measurements of nitrate, ammonium, and phosphate. Data from such instruments allow a much more detailed assessment of the spatial and temporal dynamics of nutrients. Four fruitful directions for future research include utilizing continuous sensor data to estimate rates of primary production and ecosystem respiration, linking models of the Delta with the transport and fate of dissolved nutrients, studying nutrient dynamics in various habitat types, and exploring the use of stable isotopes to trace the movement and fate of effluent-derived nutrients.

Nutrient Fluxes from Sediments in the San Francisco Bay Delta

Estuaries and Coasts (Springer) | January 1st, 2014

In September 2011 and March 2012, benthic nutrient fluxes were measured in the San Francisco Bay Delta, across a gradient from above the confluence of the Sacramento and

In September 2011 and March 2012, benthic nutrient fluxes were measured in the San Francisco Bay Delta, across a gradient from above the confluence of the Sacramento and San Joaquin Rivers to Suisun Bay. Dark and illuminated core incubation techniques were used to mea- sure rates of denitrification, nutrient fluxes (phosphate, ammonium, nitrate), and oxygen fluxes. While benthic nutrient fluxes have been assessed at several sites in northern San Francisco Bay, such data across a Delta–Bay transect have not previously been determined. Average September rates of DIN (nitrate, nitrite, ammonium) flux were net positive across all sites, while March DIN flux indicated net uptake of DIN at some sites. Denitrification rates based on the N2/Ar ratio approach were between 0.6 and 1.0 mmol m−2 day−1, similar to other mesotrophic estuarine sediments. Coupled nitrifica- tion–denitrification was the dominant denitrification pathway in September, with higher overlying water nitrate concentra- tions in March resulting in denitrification driven by nitrate flux into the sediments. Estimated benthic microalgal productivity was variable and surprisingly high in Delta sediments and may represent a major source of labile carbon to this ecosystem. Variable N/P stoichiometry was observed in these sediments, with deviations from Redfield driven by processes such as denitrification, variable light/dark uptake of nutrients by microalgae, and adsorption of soluble reactive phosphorus.

Nutrient Management Strategy for San Francisco Bay

San Francisco Bay Regional Water Quality Control Board (SFBRWQCB) | November 1st, 2012

This document presents a draft strategy for developing the science needed to make informed decisions about assessing nutrient impacts on water quality, protecting benefic

This document presents a draft strategy for developing the science needed to make informed decisions about assessing nutrient impacts on water quality, protecting beneficial uses , and managing nutrient loads to San Francisco Bay. The document first provides relevant background, after which management decisions related to nutrients are highlighted. The document then lays out a plan, developed collaboratively by the San Francisco Regional Water Quality Control Board (Water Board) and Bay stakeholders, for the technical studies required to support decisions regarding nutrient management .

Nutrient Management Strategy Science Plan Report

San Francisco Estuary Institute (SFEI) | September 9th, 2016

The San Francisco Bay (SFB) estuary receives large inputs of the nutrients nitrogen and phosphorous from anthropogenic sources, and has the potential to suffer negative

The San Francisco Bay (SFB) estuary receives large inputs of the nutrients nitrogen and phosphorous from anthropogenic sources, and has the potential to suffer negative impacts from nutrient overenrichment. Nutrient concentrations in SFB exceed those in other estuarine ecosystems where degradation is strongly expressed. To date, SFB has shown resistance to some of the classic symptoms of nutrient over-enrichment, such as excessive phytoplankton biomass as chlorophyll-a (chl-a) and low dissolved oxygen (DO). Recent observations, however, suggest that SFB’s resistance to nutrient enrichment is weakening, and have generated concern that SFB may be trending toward, or may already be experiencing, adverse impacts due to its high nutrient loads. In response to these concerns, the San Francisco Bay Regional Water Quality Control Board (SFBRWQCB) worked collaboratively with stakeholders to develop the San Francisco Bay Nutrient Management Strategy (NMS).1 The NMS lays out an overall approach for developing the underlying science to support nutrient management decisions. This report presents a Draft Science Plan for implementing the SFB NMS. The report’s main goals include: Lay out a multi-year Science Plan representing a logical sequence of studies to inform major management decisions, assuming a time-line of 10+ years. Develop an approach and rationale for sequencing and prioritizing among studies, and identify specific high-priority studies, in particular those that should proceed in FY2016- 2018. Provide realistic estimates of the time-frame and funding needed to support a Science Plan that will successfully inform management decisions. The Draft Science Plan was developed in 2014-15 with input from science advisors (Table 1.1), the NMS Steering Committee, and the NMS Nutrient Technical Work Group (Fig. 1.1). Projects are described in more detail in the first 1-3 years, and in increasingly less detail over time, recognizing that the Science Plan will be iteratively refined based on new insights gained as work progresses.

Nutrient Management Strategy Science Program

San Francisco Estuary Institute (SFEI) | September 1st, 2017

San Francisco Bay (SFB) receives large inputs of the nutrients nitrogen (N) and phosphorous (P) from anthropogenic sources. N and P are essential components of a healthy

San Francisco Bay (SFB) receives large inputs of the nutrients nitrogen (N) and phosphorous (P) from anthropogenic sources. N and P are essential components of a healthy estuary, supporting primary production at the base of the food web. However, ambient N and P concentrations in SFB exceed those in many other estuarine ecosystems, including those considered eutrophic1 and that experience nutrient-related impairment, such as excessive phytoplankton blooms and prolonged periods of low dissolved oxygen (DO). Unlike those other nutrient-enriched estuaries, though, SFB has exhibited resistance to classic eutrophication symptoms. Recent observations, however, suggest that SFB’s resistance to nutrient enrichment is weakening (e.g., Cloern et al., 2007; Cloern et al., 2010; SFEI 2014a).  These San Francisco Bay Nutrient Management Strategy (NMS) Science Program was launched in 2014 to develop the scientific foundation to support nutrient management decisions. The NMS Steering Committee, representing 13 stakeholder groups (regulators, dischargers, water purveyors, NGOs, resource agencies) oversees the NMS’ implementation, including financial oversight and alignment of NMS science activities with high priority management questions. The San Francisco Estuary Institute (SFEI) serves as the technical lead on implementing the NMS Science Program. SFEI staff work with regional collaborators to carry out NMS projects, including field investigations, monitoring, and data interpretation.