Bayesian nitrate source apportionment to individual groundwater wells in the Central Valley by use of elemental and isotopic tracers

American Geophysical Union (AGU) | July 31st, 2016

Groundwater quality is a concern in alluvial aquifers that underlie agricultural areas, such as in the San Joaquin Valley of California. Shallow domestic wells (less tha

Groundwater quality is a concern in alluvial aquifers that underlie agricultural areas, such as in the San Joaquin Valley of California. Shallow domestic wells (less than 150 m deep) in agricultural areas are often contaminated by nitrate. Agricultural and rural nitrate sources include dairy manure, synthetic fertilizers, and septic waste. Knowledge of the relative proportion that each of these sources contributes to nitrate concentration in individual wells can aid future regulatory and land management decisions. We show that nitrogen and oxygen isotopes of nitrate, boron isotopes, and iodine concentrations are a useful, novel combination of groundwater tracers to differentiate between manure, fertilizers, septic waste, and natural sources of nitrate. Furthermore, in this work, we develop a new Bayesian mixing model in which these isotopic and elemental tracers were used to estimate the probability distribution of the fractional contributions of manure, fertilizers, septic waste, and natural sources to the nitrate concentration found in an individual well. The approach was applied to 56 nitrate-impacted private domestic wells located in the San Joaquin Valley. Model analysis found that some domestic wells were clearly dominated by the manure source and suggests evidence for majority contributions from either the septic or fertilizer source for other wells. But, predictions of fractional contributions for septic and fertilizer sources were often of similar magnitude, perhaps because modeled uncertainty about the fraction of each was large. For validation of the Bayesian model, fractional estimates were compared to surrounding land use and estimated source contributions were broadly consistent with nearby land use types.

Before the Well Runs Dry: Improving the Linkage Between Groundwater and Land Use Planning

Stanford University | April 17th, 2014

There is no comprehensive regulation of groundwater use in the state of California,* and the right to withdraw groundwater is based on surface land ownership. This create

There is no comprehensive regulation of groundwater use in the state of California,* and the right to withdraw groundwater is based on surface land ownership. This creates a direct linkage between every land use that requires water and the groundwater underneath that land. Because so many aspects of groundwater use are not regulated by the state, local governments’ land use decisions become a key driver of demands on groundwater. Nonetheless, land use decisions and planning are not well coordinated with groundwater management. Understanding how land use decisions affect groundwater resources has become increasingly important in recent years, as groundwater provides approximately 30 percent of California’s water supply in average years and 40 percent of the supply in dry years. In some places, the reliance on groundwater during droughts is much higher, due to reduced supplies of surface water. Growth from housing and irrigated agriculture, among other demands, have led to chronic overdraft and declining groundwater elevations in many communities that rely heavily on groundwater. To address this problem, Water in the West convened groundwater managers, land use planners, water lawyers, consultants and academics at Stanford University for an Uncommon Dialogue in the fall of 2013. Its aim was to discuss a growing consensus that more effective integration of land use planning and groundwater management is an essential component of preserving groundwater aquifers for the future, and to share possible means of accomplishing this in California. This report, shaped in part by the Dialogue, provides the background and regulatory context for land use planning and groundwater management in California, shares case studies that highlight the intersection of groundwater and land use, and makes specific recommendations to improve the linkage between land use decisions and groundwater management in the state. *The Sustainable Groundwater Management Act (SGMA) was signed into law five months after this was published. 

Benefit Accounting of Nature-Based Solutions for Watersheds Guide - Version 2

Pacific Institute | August 23rd, 2023

This guide helps users account for and measure the stacked water,1 carbon, biodiversity and socio-economic benefits of a Nature-Based Solution NBS project. Accounting for

This guide helps users account for and measure the stacked water,1 carbon, biodiversity and socio-economic benefits of a Nature-Based Solution NBS project. Accounting for these benefits will improve a company’s impact reporting and help build the business case for green solutions, thereby supporting widespread investment, implementation and upscaling of NBS. This work will increase awareness of the value of NBS, not only for ecosystem health and community development, but also for companies directly.

Benefit Accounting of Nature-Based Solutions for Watersheds Landscape Assessment

United Nations (UN) | August 3rd, 2020

This landscape assessment is the outcome of Phase 1 of a tri-phased project and was designed to inform the path forward for engaging the private sector to invest in natu

This landscape assessment is the outcome of Phase 1 of a tri-phased project and was designed to inform the path forward for engaging the private sector to invest in nature-based solutions (NBS). A literature review was undertaken to understand the contemporary thinking around NBS and identify key opportunities and challenges faced by decision makers, practitioners and researchers. Interviews conducted with representatives of businesses, civil society and academia who have already implemented NBS projects or are looking to do so yielded qualitative responses to complement or contrast with the findings from the literature review.

Beyond the Haze: A UC Dust Report on the Causes, Impacts, and Future of Dust Storms in California

University of California, San Diego (UC San Diego) | December 5th, 2024

This report is intended to be a comprehensive summary of the current state of knowledge of dust storms in California, including where dust storms occur, the features cont

This report is intended to be a comprehensive summary of the current state of knowledge of dust storms in California, including where dust storms occur, the features contributing to their geographic distribution, factors driving historical and likely future changes in dust, the impact dust storms have on human health, the economy, and environment of the state, and an assessment of what is needed to mitigate or adapt to those impacts. The purpose of this report is to be a resource to the public, community-based organizations, state agencies, and policy makers on dust storms in California. The information here is intended to help guide future adaptation and mitigation efforts and identify critical gaps in understanding that impede those efforts.

Bringing Water and Land Use Together

Local Government Commission | April 11th, 2019

In 2005, the California Legislature passed new laws that enable communities to join together to adopt Integrated Regional Water Management (IRWM) policies and practices.

In 2005, the California Legislature passed new laws that enable communities to join together to adopt Integrated Regional Water Management (IRWM) policies and practices. This comprehensive planning approach considers water resources in the context of an interconnected watershed with a network of regional governance, rather than as a combination of fragmented parts. Unfortunately, the IRWM program is dominated by the water sector and in most regions has not pursued alignment with land use. Similarly, the Sustainable Communities Strategies (SCS) mandated through SB 375 establish a framework for aligning land use practices (predominantly housing and transportation) across jurisdictions within a larger geographic region. Yet very few SCSs have taken water resources into account. While water management and land-use planning remain highly fragmented across the state, we are making progress toward a more integrated approach, especially when setting new state-level policies, regulations and guidance. The 2014 Sustainable Groundwater Management Act (SGMA) is a leap forward in this direction. For the first time, local land use agencies have an opportunity to be full partners with water agencies in shaping groundwater governance. It is too soon to determine how well these two sectors are integrating under SGMA, but early results are promising.

Building Ecological Resilience in Highly Modified Landscapes

Oxford University Press (OUP) | November 7th, 2018

Ecological resilience is a powerful heuristic for ecosystem management in the context of rapid environmental change. Significant efforts are underway to improve

Ecological resilience is a powerful heuristic for ecosystem management in the context of rapid environmental change. Significant efforts are underway to improve the resilience of biodiversity and ecological function to extreme events and directional change across all types of landscapes, from intact natural systems to highly modified landscapes such as cities and agricultural regions. However, identifying management strategies likely to promote ecological resilience remains a challenge. In this article, we present seven core dimensions to guide long-term and large-scale resilience planning in highly modified landscapes, with the objective of providing a structure and shared vocabulary for recognizing opportunities and actions likely to increase resilience across the whole landscape. We illustrate application of our approach to landscape-scale ecosystem management through case studies from two highly modified California landscapes, Silicon Valley and the Sacramento–San Joaquin Delta. We propose that resilience-based management is best implemented at large spatial scales and through collaborative, cross-sector partnerships.

Bulletin No. 122, Ventura County and Upper Santa Clara River Drainage Area Land and Water Use Survey, 1961

California Department of Water Resources (DWR) | April 1st, 1965

Bulletin No. 24-60, Coastal Los Angeles County Land and Water Use Survey, 1960

California Department of Water Resources (DWR) | April 9th, 1964

Bulletin No. 35, Permissible Economic Rate of Irrigation Development in California

California Department of Water Resources (DWR) | October 30th, 1930