Estuary News, October 2021

San Francisco Estuary Partnership (SFEP) | October 15th, 2021

Estuary News, September 2016

San Francisco Estuary Partnership (SFEP) | September 15th, 2016

Exploring scientific and management implications of upper trophic level food webs in the Delta

Delta Stewardship Council (Delta Council) | April 17th, 2024

The Sacramento-San Joaquin Delta (the Delta) has complex and evolving ecosystems characterized by multiple food webs that vary in time and space. Here, food webs are defi

The Sacramento-San Joaquin Delta (the Delta) has complex and evolving ecosystems characterized by multiple food webs that vary in time and space. Here, food webs are defined as the network of species interactions (competition, predation) and interactions with their environment that are related through the flow of energy through the ecosystem (e.g., Paine 1980). Physical modifications, in addition to the introduction of non-native species and the changing climate, have significantly altered the structure and energetic pathways of the food webs for decades. The science clearly suggests that predicting the impacts of habitat restoration, fisheries, changes in environmental drivers (e.g., climate, changes in nutrient loading, invasive species) on the ecological carrying capacity and productivity of the Delta, as well as the bioaccumulation of contaminants on species or the ecosystem, requires an understanding of food web processes.

Gaps and opportunities in nitrogen pollution policies around the world

Nature Portfolio (Springer Nature) | July 6th, 2020

Nitrogen pollution is an important environmental issue gaining traction in policy circles. However, there is little understanding of current nitrogen policies around the

Nitrogen pollution is an important environmental issue gaining traction in policy circles. However, there is little understanding of current nitrogen policies around the world: whether they account for nitrogen’s unique ability to exacerbate multiple environmental impacts or balance nitrogen’s dual role as an essential agricultural input and major pollutant. Here we assemble and analyse the first database of nitrogen policies generated by national and regional legislatures and government agencies, a collection of 2,726 policies across 186 countries derived from the ECOLEX database. The database covers all major environmental sinks (such as air, water and climate), economic sectors (including agriculture, wastewater and industry) and policy instruments (from market mechanisms to regulatory standards). We find that sink-centred policies are focused predominantly on water, mirroring the distribution of nitrogen’s global environmental and human health costs. However, policy integration across sinks is severely lacking, which heightens the risk of substituting one form of nitrogen pollution for another. Moreover, two-thirds of agricultural policies (ranging from broad sectoral programmes to nitrogen-specific measures) incentivize nitrogen use or manage its commerce, demonstrating the primacy of food production over environmental concerns.

Historical Ecology and Landscape Change in the Central Laguna de Santa Rosa

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

This study synthesizes a diverse array of data to examine the ecological patterns, ecosystem functions, and hydrology that characterized a central portion of the Laguna d

This study synthesizes a diverse array of data to examine the ecological patterns, ecosystem functions, and hydrology that characterized a central portion of the Laguna de Santa Rosa during the mid-19th century, and to analyze landscape changes over the past 150 years. The primary purpose of this study was to help guide restoration actions and other measures aimed at reducing nutrient loads within this portion of the Laguna de Santa Rosa watershed.

Hydrodynamic and Water Quality Model Calibration and Application in San Francisco Bay

San Francisco Estuary Institute (SFEI) | September 3rd, 2018

To answer management questions about nutrient related water quality in San Francisco Bay, hydrodynamic and biogeochemical models have been developed. This report outline

To answer management questions about nutrient related water quality in San Francisco Bay, hydrodynamic and biogeochemical models have been developed. This report outlines the development of both of these models. Section 2 is the description and validation of the hydrodynamic model, previously completed in December 2017 for the San Francisco Bay Interim Model Validation Report, but included here for completeness. Section 3 of this report covers the description and validation the biogeochemical model.

Hydrodynamic Model Development Report: Sacramento-San Joaquin River Delta and Suisun Bay (Water Year 2016)

San Francisco Estuary Institute (SFEI) | December 13th, 2019

This report describes work related to hydrodynamic model development for the San Francisco Bay-Delta Estuary, undertaken as part of a broader eort to develop and apply co

This report describes work related to hydrodynamic model development for the San Francisco Bay-Delta Estuary, undertaken as part of a broader eort to develop and apply coupled biogeochemical-hydrodynamic models to inform nutrient management decisions. The primary intended application of the hydrodynamic model output is for use as input to an offline coupled biogeochemical model to simulate a wide range of state variables and processes, including: advective and dispersive transport, nutrient transformations, phytoplankton production, benthic and pelagic grazing, sediment diagenesis, and oxygen cycling.

Managing a cyanobacteria harmful algae bloom “hotspot” in the Sacramento – San Joaquin Delta, California

Journal of Environmental Management (Elsevier) | December 10th, 2023

National Strategy for the Development of Regional Nutrient Criteria

U.S. Environmental Protection Agency (EPA) | June 1st, 1998

In February of this year, President Clinton and Vice President Gore released a comprehensive Clean Water Action Plan. The Action Plan provides a blueprint for Fed

In February of this year, President Clinton and Vice President Gore released a comprehensive Clean Water Action Plan. The Action Plan provides a blueprint for Federal agencies to work with States and others stakeholders in restoring and protecting the Nation’s water resources and addresses three major goals: enhanced protection from public health threats posed by water pollution; more effective control of polluted runoff; and promotion of water quality restoration and protection on a watershed basis. A key part of the Action Plan provides for expanded efforts to reduce nutrient overenrichment of waters. Nutrients, in appropriate amounts, are essential to the health of aquatic systems. Excessive nutrients, however, can result in excessive growth of macrophytes or phytoplankton and potentially harmful algal blooms leading to oxygen declines, imbalance of aquatic species, public health threats, and a general decline in the aquatic resource. Recent reports on water quality conditions provided by States indicate that nutrients are the leading cause of impairment in lakes and coastal waters and the second leading cause of impairment to rivers and streams. Nutrient overenrichment has also been strongly linked to the large hypoxic zone in the Gulf of Mexico and to recent outbreaks of the toxic microorganism Pfiesteria along the Gulf and Mid-Atlantic coasts. The Action Plan calls on EPA to accelerate the development of scientific information concerning the levels of nutrients that cause water quality problems and to organize this information by different types of waterbodies (e.g. streams, lakes, coastal waters, wetlands) and by geographic regions of the country. EPA is also to work with States and Tribes to adopt criteria (i.e. numeric concentration levels) for nutrients, including nitrogen and phosphorus, as part of enforceable State water quality standards under the Clean Water Act.

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.