Cover cropping and no-tillage improve soil health in an arid irrigated cropping system in California’s San Joaquin Valley, USA

Soil and Tillage Research (Elsevier) | January 3rd, 2017

The concept of soil health has attracted considerable attention during the past two decades, but few studies have focused on the effects on soil health of long-term soil

The concept of soil health has attracted considerable attention during the past two decades, but few studies have focused on the effects on soil health of long-term soil management in arid irrigated environments. We investigated the effects of cover cropping and no-till management on soil physical and chemical properties during a 15-year experiment in California’s San Joaquin Valley (SJV) USA. Our objective was to determine if soil health could be improved by these practices in an annual crop rotation. The impact of long-term no-tillage (NT) and cover cropping (CC) practices, alone and in combination, was measured and compared with standard tillage (ST) with and without cover crops (NO) in irrigated row crops after 15 years of management. Soil aggregation, rates of water infiltration, content of carbon, nitrogen, water extractable organic carbon (WEOC) and organic nitrogen (WEON), residue cover, and biological activity were all increased by NT and CC practices relative to STNO. However, effects varied by depth with NT increasing soil bulk density by 12% in the 0–15 cm depth and 10% in the 15–30 cm depth. Higher levels of WEOC were found in the CC surface (0–5 cm) depth in both spring and fall samplings in 2014. Surface layer (0–15 cm) WEON was higher in the CC systems for both samplings. Tillage did not affect WEON in the spring, but WEON was increased in the NT surface soil layer in the fall. Sampling depth, CC, and tillage affected 1-day soil respiration and a soil health index assessment, however the effects were seasonal, with higher levels found in the fall sampling than in the spring. Both respiration and the soil health index were increased by CC with higher levels found in the 0–5 cm depth than in the 5–15 and 15–30 cm depths. Results indicated that adoption of NT and CC in arid, irrigated cropping systems could benefit soil health by improving chemical, physical, and biological indicators of soil functions while maintaining similar crop yields as the ST system.

Critical Aquifer Overdraft Accelerates Degradation of Groundwater Quality in California's Central Valley During Drought

American Geophysical Union (AGU) | September 1st, 2021

It has been established that wells are at risk to run dry when groundwater levels decline during drought, but associated impacts to water quality are poorly understood. 

It has been established that wells are at risk to run dry when groundwater levels decline during drought, but associated impacts to water quality are poorly understood. This study examined 30 yr of data from California's Central Valley to find dramatic groundwater-level declines during drought were associated with worsening groundwater quality. This likely happens because increased pumping during drought can draw shallow, contaminated groundwater to depths commonly tapped by public drinking water wells. This is the first study of its kind to show direct linkages between drought and groundwater quality at such a broad spatial scale

Critical Assessment of the Delta Smelt Population in the San Francisco Estuary, California

University of California, Davis (UC Davis) | July 1st, 2005

Critical Review: Regulatory Incentives and Impediments for onsite Graywater Reuse in the United States

Water Environment Research | July 11th, 2013

Graywater is a potential water source for reducing water demand. Accordingly, a review was undertaken of graywater reuse regulations and guidelines within the 50 United

Graywater is a potential water source for reducing water demand. Accordingly, a review was undertaken of graywater reuse regulations and guidelines within the 50 United States. Major issues considered included acceptability for graywater segregation as a separate wastewater stream, allowable graywater storage, onsite treatment requirements, and permitted graywater use applications. Existing regulations and plumbing codes in the different states suggest that there are impediments to overcome but also potential incentives for graywater reuse. It is encouraging that regulations in 29 states promote safe graywater reuse, but there are also inconsistencies between plumbing codes and other regulations within and among the 50 states. Impediments to graywater reuse include disallowances of graywater segregation or collection, and restriction of graywater reuse to mostly subsurface irrigation with limited indoor use permission. Ease on restrictions and guidelines to promote development of low-cost and proven treatment technologies are needed to promote graywater reuse.

Cruise Plan: 2016 Regional Monitoring Program (RMP) Bivalve Deployment Cruise

San Francisco Estuary Institute (SFEI) | June 2nd, 2016

This report details plans associated with the biennial Regional Monitoring Program for Water Quality in the San Francisco Estuary (RMP) bivalve deployment cruise. This Cr

This report details plans associated with the biennial Regional Monitoring Program for Water Quality in the San Francisco Estuary (RMP) bivalve deployment cruise. This Cruise Plan was developed based upon the decisions of the RMP Technical Review Committee in 2002 to reduce the number of bivalve transplant stations from twelve to nine, utilize deployment cages rather than bags at all stations, and deploy only Mytilus californianus. These changes went into effect with the 2003 program and continued through the 2012 deployments. In 2014, the RMP Technical Review Committee reduced bivalve deployment transplant stations from 9 to 7 stations, 3 of which are back-up deployment sites. In addition, as instituted initially with the 2006 deployments, there is no mid-deployment maintenance cruise, as previous analyses showed no difference in bivalve growth or survival between maintained and unmaintained deployments. 

Cruise Plan: 2016 Regional Monitoring Program (RMP) Bivalve Retrieval Cruise

San Francisco Estuary Institute (SFEI) | September 27th, 2016

This report details plans associated with the biennial Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) bivalve retrieval cruise. This Cruise Plan

This report details plans associated with the biennial Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) bivalve retrieval cruise. This Cruise Plan was developed based upon the decisions of the RMP Technical Review Committee in 2002 to reduce the number of bivalve transplant stations from twelve to nine, utilize deployment cages rather than bags at all stations, and deploy only Mytilus californianus. These changes went into effect with the 2003 program and continued through the 2012 deployments. In 2014, the RMP Technical Review Committee reduced bivalve deployment transplant stations from 9 to 7 stations, 3 of which are back-up deployment sites. In addition, as instituted initially with the 2006 deployments, there is no mid-deployment maintenance cruise, as previous analyses showed no difference in bivalve growth or survival between maintained and unmaintained deployments. 

Cruise Report 2016 Regional Monitoring Plan (RMP) Bivalve Deployment Cruise, June 28 – July 1, 2016

San Francisco Estuary Institute (SFEI) | July 7th, 2016

This report describes activities associated with the 2016 bivalve deployment cruise of the Regional Monitoring Program (RMP). Measurement of contaminant concentrations in

This report describes activities associated with the 2016 bivalve deployment cruise of the Regional Monitoring Program (RMP). Measurement of contaminant concentrations in transplanted bivalves accumulated during dry season deployment is designed to provide long-term data on the bioaccumulation of select trace elements and trace organic compounds in tissue throughout the Estuary. 

Cruise Report: 2016 Regional Monitoring Program (RMP) Bivalve Retrieval Cruise, September 30 – October 13, 2016

San Francisco Estuary Institute (SFEI) | November 3rd, 2016

This report describes activities associated with the 2016 bivalve retrieval cruise of the Regional Monitoring Program for Water Quality in the San Francisco Estuary (RMP)

This report describes activities associated with the 2016 bivalve retrieval cruise of the Regional Monitoring Program for Water Quality in the San Francisco Estuary (RMP). Measurement of contaminant concentrations in transplanted bivalves accumulated during dry season deployment is designed to provide long-term data on the bioaccumulation of trace elements and trace organic compounds in tissue throughout the Estuary. 

Cultivating climate resilience in California agriculture: Adaptations to an increasingly volatile water future

National Academy of Sciences (NAS) | July 29th, 2024

Cultivating effective utility-regulator relationships around innovation: Lessons from four case studies in the U.S. municipal wastewater sector

PLOS | August 26th, 2022

Regulation is critical for protecting public and environmental health but is often perceived as a barrier to innovation in the U.S. municipal wastewater sector. Before a

Regulation is critical for protecting public and environmental health but is often perceived as a barrier to innovation in the U.S. municipal wastewater sector. Before a wastewater utility can implement a new technology, it must navigate applicable regulatory processes and obtain necessary approvals, often including obtaining an updated wastewater discharge permit. While all regulatory processes involve interactions between regulators and regulated entities, innovative projects may require them to engage in new ways, heightening the importance of the relationships between them. We investigated four case studies to examine how regulatory relationships affect municipal wastewater utilities’ efforts to adopt new technologies. Through cross-case analysis, we identified five interconnected characteristics of regulatory relationships that appear to facilitate innovation, and whose absence could impede it: clarity, capacity building, continuity, trust, and bounded flexibility. Appropriately applied bounded flexibility—such as using regulatory discretion to tailor permits to reflect the particular risks, benefits, and information needs of the technology at issue—may be key for enabling socially and environmentally beneficial innovation. Yet all five characteristics play important and mutually reinforcing roles in supporting innovation. By cultivating these characteristics in their relationships, both utilities and regulators can take responsibility for enabling appropriate implementation of innovative technologies. However, some parties, particularly small and under-resourced utilities, may find cultivating these characteristics difficult. Therefore, sector-wide support for effective utility-regulator relationships, including coordinated regulatory and funding programs targeted to meet small utilities’ needs, may be needed to bring beneficial innovation within reach for many wastewater utilities and the communities they serve.