Majority of global river flow sustained by groundwater

Nature Portfolio (Springer Nature) | July 19th, 2024

Groundwater-sustained baseflow is a vital source of river flow, especially during dry seasons. The proportion of river flow sustained by baseflow—the baseflow index—i

Groundwater-sustained baseflow is a vital source of river flow, especially during dry seasons. The proportion of river flow sustained by baseflow—the baseflow index—is essential for assessing fluvial nutrient cycling and contaminant transport. However, the global baseflow index remains highly uncertain, with current Earth system model simulations ranging from 12% to 94%. Here we estimate the global baseflow index to be 59% ± 7% based on an emergent constraint approach, which integrates 50 Earth system models with baseflow indices derived from streamflow observations in 15,567 basins. Our observational constraint indicates that at least 21% ± 3% of precipitation recharges groundwater, which is approximately double the figure reported in the Sixth Assessment Report of the United Nations Intergovernmental Panel on Climate Change. Thus, our research suggests a more active role of groundwater in the global water cycle than most Earth system models currently simulate. We present evidence that the considerable disagreement in simulated baseflow stems from unrealistic and varied model representations of infiltration, aquifer structure and groundwater dynamics. These processes should be prioritized so that models can capture active groundwater–river connections.

Making Conservation a California Way of Life - Revised

California State Water Resources Control Board (SWRCB) | March 12th, 2024

Making Green Infrastructure Work in the Bay Area

San Francisco Estuary Institute (SFEI) | July 1st, 2016

Making Nature's City: A science-based framework for building urban biodiversity

San Francisco Estuary Institute (SFEI) | July 1st, 2019

Cities will face many challenges over the coming decades, from adapting to a changing climate to accommodating rapid population growth. A related suite of challenges th

Cities will face many challenges over the coming decades, from adapting to a changing climate to accommodating rapid population growth. A related suite of challenges threatens global biodiversity, and many species face potential extinction. While urban planners and conservationists have long treated these issues as distinct, there is growing evidence that cities not only harbor a significant fraction of the world’s biodiversity, but that they can also be made more livable and resilient for people, plants, and animals through nature-friendly urban design. Urban ecological science can provide a powerful tool to guide cities towards more biodiversity-friendly design. However, current research remains scattered across thousands of journal articles and largely inaccessible to practitioners. Making Nature’s City fills this gap, synthesizing global research to develop a science-based approach for supporting nature in cities. We identify seven key elements of urban form and function that work together to maximize biodiversity, and we illustrate these elements through a case study in California’s Silicon Valley. Using the framework developed in this report, urban designers and local residents can work together to link local parks, greenways, green roofs, street trees, stormwater basins, commercial landscaping, and backyards to support biodiversity while making cities better places to live. As we envision the healthier, and more resilient cities, Making Nature’s City provides practical guidance for the many actors who together will shape the nature of cities.

Making the Delta a Better Place for Native Fishes

Orange County Coastkeeper | March 1st, 2018

The Sacramento-San Joaquin Delta is the heart of California’s water delivery system, connecting the precipitation-rich regions of the north with the dry farmlands and

The Sacramento-San Joaquin Delta is the heart of California’s water delivery system, connecting the precipitation-rich regions of the north with the dry farmlands and demanding urban areas of the south and coast, including the Bay Area. Scarce water resources create conflicts between people and fishes; as demand by people for water grows, less water is available for the environment. This white paper explores the ways to keep the native fishes, and the functional ecosystems they require, from disappearing. Our analysis is fish-oriented because salmon, smelt, and other declining fishes are major drivers of decisions on where to focus aquatic restoration efforts.  The goals of this white paper are to first provide a brief introduction to the Delta and then to describe why restoration of native fishes and natural processes is such a challenge in this system. We follow this with some general guidelines for restoration projects in the Delta and apply those guidelines with a project evaluation tool. We used this tool to evaluate 26 projects, mostly part of EcoRestore, to provide insights to help determine action items. We then present 17 action items, listed below, some of which can be accomplished fairly quickly, some that will take longer, and few that will have to be continuous. But taken together, our recommended actions could significantly improve the welfare of native fishes and help to create a novel aquatic ecosystem with many desirable features.

Making the Most of Water for the Environment: A Functional Flows Approach for California’s Rivers

Public Policy Institute of California (PPIC) | August 25th, 2020

In California, water and land management activities have substantially altered river flows and degraded river channels and their floodplains. The result has been a precip

In California, water and land management activities have substantially altered river flows and degraded river channels and their floodplains. The result has been a precipitous decline in native fish populations, including the collapse of valued salmon fisheries, and widespread imperilment of freshwater biodiversity. Environmental flows—flows in rivers and streams necessary to sustain ecosystem health—are essential to reversing these trends. Yet many rivers in California lack environmental flows. And for those rivers with such protections, environmental flows are typically established at static minimum levels, which fail to preserve the natural seasonal and interannual variability of flow that sustains healthy ecosystems. A new approach to managing environmental water is needed. 

Making Water Conservation a California Way of Life Proposed Regulation Review of the Water Board’s Standardized Regulatory Impact Analysis (SRIA)

Mesa Water District | September 28th, 2023

Making Water Conservation a California Way of Life: Implementing Executive Order B-37-16

State of California | April 7th, 2017

In May of 2016 Governor Edmund G. Brown Jr. signed Executive Order (B?37?16) that instructed State agencies to help Californians adopt permanent changes to use water more

In May of 2016 Governor Edmund G. Brown Jr. signed Executive Order (B?37?16) that instructed State agencies to help Californians adopt permanent changes to use water more wisely. The Executive Order laid out a framework for moving the state from temporary, emergency water conservation measures to a more durable approach customized to the unique conditions of each local water agency. This report builds upon the Executive Order and provides recommendations for how to implement long?term improvements to water supply management that support water conservation.

Making Water Conservation a California Way of Life: Primer of 2018 Legislation on Water Conservation and Drought Planning Senate Bill 606 (Hertzberg) and Assembly Bill 1668 (Friedman)

California State Water Resources Control Board (SWRCB) | November 30th, 2018

In 2018, the California State Legislature (Legislature) enacted two policy bills, (Senate Bill (SB) 606 (Hertzberg) and Assembly Bill (AB) 1668 (Friedman)), to establish

In 2018, the California State Legislature (Legislature) enacted two policy bills, (Senate Bill (SB) 606 (Hertzberg) and Assembly Bill (AB) 1668 (Friedman)), to establish a new foundation for long-term improvements in water conservation and drought planning to adapt to climate change and the resulting longer and more intense droughts in California. These two bills amend existing law to provide expanded and new authorities and requirements to enable permanent changes and actions for those purposes, improving the state's water future for generations to come.

Making Waves: One Water Quality Standardization Concept – A Leap for Sustainable Water Management

Elsevier | February 20th, 2026

Current water management frameworks are often disjointed, failing to consider the full range of potential water uses. This fragmentation leads to inconsistent regulations

Current water management frameworks are often disjointed, failing to consider the full range of potential water uses. This fragmentation leads to inconsistent regulations; for example, potable water production from wastewater often faces stricter quality standards than water sourced from even wastewater-impacted surface waters. This article proposes a use-based approach to water management, developing water quality standards that account for the economic, public health, and ecological needs of downstream users. We advocate for expanding the concept of water quality from simple pollutant removal to “building water” to match the needs of users so desired constituents are either left in the source water or added to treated water to meet specific user needs. This strategy requires a multidimensional, risk-based regulatory framework, supported by advances in data science and affordable measurement tools for effective enforcement. Such advancement enables a move beyond binary standards to foster sustainable global water resource management and mitigate scarcity.