Nature-based solutions extend the lifespan of a regional levee system under climate change

Nature Portfolio (Springer Nature) | May 9th, 2025

Navigability and its Consequences: State Title, Mineral Rights, and the Public Trust Doctrine

Social Science Research Network (SSRN) | June 12th, 2014

“Navigability” and “navigable waters” are two of the most complex terms of art in American law because their meanings vary from context to context. A “navigable

“Navigability” and “navigable waters” are two of the most complex terms of art in American law because their meanings vary from context to context. A “navigable water” for purposes of the federal courts’ admiralty jurisdiction is not precisely the same thing as a “navigable water” for Commerce Clause purposes, and the Commerce Clause definition can be further refined in statute like the federal Clean Water Act. Other important federal law definitions of navigability govern state title to banks and beds of waterways and the scope of the federal navigation servitude. As this article will discuss, these tests overlap considerably, and attempts to distinguish them can cause confusion. State law definitions of “navigability” for state regulatory purposes complicate the multiple valences of “navigable water” even further. This article provides an overview of some of the more important definitions of “navigability” and “navigable waters.” In general, labeling a waterway as “navigable” signals that either the federal government or the public acquires some right to the waterway in question. However, if the waterway also meets the “navigable water” test for state title, complicated legal relationships among the federal government, the relevant state, the general public, and private riparian landowners almost inevitably follow.

Navigating a Flood of Information Evaluating and Integrating Climate Science into Groundwater Planning in California

Union of Concerned Scientists | November 1st, 2017

In early 2017, northern California experienced record-setting levels of precipitation. The amount of rain and snow from October 2016 through February 2017 was the greates

In early 2017, northern California experienced record-setting levels of precipitation. The amount of rain and snow from October 2016 through February 2017 was the greatest in the 122 years of California record-keeping. As the reservoir behind Oroville Dam quickly filled to capacity, a torrent of excess water was let out through the main spillway. Shortly thereafter the spillway began to collapse, leading to massive soil erosion and concerns that the erosion could undermine the dam itself. Fears of a catastrophic dam breach led to the evacuation of around 180,000 residents downstream from the dam. While we do not know how much climate change contributed to this particular event, we do know that climate change is making extreme events more common (Black et al. 2016; Mote et al. 2016; Otto 2016). While reports indicate that management failures may have played in an important role in the Oroville disaster, it is also true that this event took place in the context of extreme weather, and that climate change is increasing pressure on structures and communities. This finding is not limited to highprofile infrastructure such as the Oroville Dam. Much of our water infrastructure, management tools, institutions, and planning mechanisms are not designed for the increased magnitude and frequency of such extremes—making the state, its environment, and its water resources vulnerable to the changes we are likely to see in the coming decades. In California, groundwater contributes more than half of the state’s water supply during dry years (DWR 2009). Therefore, understanding the impacts that climate change will have on this critical resource will be of particular importance for the state’s water and food security over the long term. To that end, Governor Jerry Brown issued Executive Order B-30-15 that, along with setting ambitious greenhouse gas reduction targets, requires state agencies take climate change into account in their planning and investment decisions. In addition, California’s Sustainable Groundwater Management Act (SGMA), passed by the legislature in 2014, requires that Groundwater Sustainability Agencies (GSAs) explicitly assess the impacts of climate change and incorporate these assessments into their Groundwater Sustainability Plans (GSPs). Under the legislation, GSAs must develop and implement GSPs to achieve sustainable groundwater management in all high- and medium-priority groundwater basins in the state. Within these plans, GSAs are required to provide “[p]rojected water budget information for population, population growth, climate change, and sea level rise” (CWR 354.18(d)(3)). Additionally, projected water budgets must “identify the uncertainties of these projected water budget components,” including uncertainties in projected hydrology, water demand, and surface water supply resulting from sea level rise, land use changes, population growth, and climate change (CWR 354.18(c)(3)). To meet these regulatory requirements, plans must “rely on the best available information and best available science to quantify the water budget for the basin” (CWR 354.18(e)). Yet, it can be difficult to identify the best approach to incorporating climate change into local plans. The purpose of this white paper is to assist in that challenging task. The consequences of not incorporating climate change into water planning can be severe, leading to unforeseen costs and even threatening lives. It is therefore the intention of this white paper to: • provide water managers and other decision-makers across the state with an overview of climate models, their component parts, and key terminology • provide a framework for evaluating and comparing the various approaches currently employed by the state and federal agencies to incorporating climate change into state-level water planning documents • recommend a four-step process to incorporate future climate projections into local GSPs Recognizing the importance of climate change impacts on the state’s water supply, the California Department of Water Resources (DWR) has devoted a significant amount of time and expertise to integrating climate change into water planning. In 2012, DWR convened the Climate Change Technical Advisory Group (DWR CCTAG) to advise DWR on the scientific aspects of climate change, the impact of climate change on water resources, the use and creation of planning approaches and analytical tools, and the development of adaptation responses. The DWR CCTAG released a report in 2015, Perspectives and Guidance for Climate Change Analysis, which makes several recommendations for future work. One central theme is the need to develop guidance and support for water managers and planners. Factoring climate change into water management decisions requires future projections of how climate change will impact water-relevant factors such as temperature and precipitation—projections that are generally derived from global climate models. However, incorporating climate change into water planning for any given community or groundwater basin can be difficult, not only because of the technical expertise required to do so, but also because the effects of climate change are spatially and temporally variable. Although the scientific community has high confidence in a key set of variables for the planet as a whole, translating global estimates of climate change to specific geographical areas creates uncertainty. Fortunately, there are tools and methods to address uncertainty. As is the case for other natural phenomena that are difficult to predict with precision, such as earthquakes, uncertainty cannot be an excuse for inaction. Scientific and technical tools can substantially assist in creating plans that cope with an uncertain future. This white paper does not directly address the role of hydrologic models themselves, but rather addresses how climate change information can be incorporated into hydrologic models as water managers seek to comply with the requirements of SGMA. The process of incorporating climate change into water management decisions has several steps, starting with running global climate models to produce future climate projections, which are then used as inputs to hydrologic models (Figure 1). We recognize that GSAs are likely to engage at different levels of technical sophistication with climate data and that the majority will seek out the services of technical experts. Ultimately, it is our intent that this white paper equip water managers with sufficient knowledge about climate change projections to understand, evaluate, and direct the work of the technical experts and consultants. Using appropriate climate change information is vital to ensuring that water managers capture potential future water resource conditions. This white paper is organized into three main sections. The first section provides a general overview of climate models, including their strengths and limitations and the type of information they can provide, and describes a framework for incorporating their output into management decisions. The second section addresses how to incorporate climate change into planning involving imported water supplies. The third section turns to planning for local water supplies and proposes a process for incorporating appropriate climate change data into GSPs.

Navigating Groundwater-Surface Water Interactions under the Sustainable Groundwater Management Act

Center for Law, Energy, and the Environment (CLEE) | March 28th, 2018

California’s Sustainable Groundwater Management Act (SGMA), passed in 2014, recognizes and addresses connections between surface water and groundwater. The st

California’s Sustainable Groundwater Management Act (SGMA), passed in 2014, recognizes and addresses connections between surface water and groundwater. The statute is California’s first statewide law to explicitly reflect the fact that surface water and groundwater are frequently interconnected and that groundwater management can impact groundwater-dependent ecosystems, surface water flows, and the beneficial uses of those flows. As such, SGMA partially remedies the historically problematic practice of treating groundwater and surface water as legally distinct resources. SGMA requires groundwater sustainability agencies (GSAs) to manage groundwater to avoid six undesirable results, including significant and unreasonable adverse impacts on beneficial uses of surface water. While this aspect of SGMA is clearly important, significant uncertainties exist regarding how GSAs will actually define and achieve this goal. Addressing SGMA’s requirements for groundwater-surface water interactions will be difficult. Defining the issues at stake in any given basin, let alone successfully balancing the range of uncertainties and potentially conficting interests, will pose challenges for many GSAs. No clear, pre-defned formula exists to guide GSAs in determining what significant and unreasonable depletions of interconnected surface water will be, or whether planned actions will sufficiently avoid them. Yet they are required to do so. Many GSAs will face pressure to aggressively address impacts on surface water in their basin. Many will face equal or greater pressure not to draw the line. Nevertheless, it will fall to the GSAs to make a determination, and to defend it in their groundwater sustainability plans (GSPs). Therefore, GSAs will likely take on some level of risk—of successful political opposition to their GSP, of successful legal challenges to their GSP, of their GSP performing ineffectively, or of all of these outcomes. Given the aggressive timeline inherent to SGMA, addressing this risk early will be crucial for preserving management options. Challenges and risk are not the whole story, however. The process of addressing groundwater-surface water interactions also ofders GSAs an opportunity to help communities and other stakeholders resolve, or avoid, difficult conflicts, and to do so in lasting ways. While California law has only recently begun to seriously address conflicts between surface and groundwater uses, those conflicts have been occurring for decades, and in some places for over a century. SGMA, in other words, did not create conflict between groundwater pumping and beneficial uses of surface water; instead it created an opportunity—as well as an obligation—to respond to those challenges. Embracing that opportunity will not be easy, but GSAs that take SGMA as an opportunity to resolve longstanding issues can do lasting good. The research presented here examines some of the legal and institutional questions that will inevitably arise as GSAs seek to address groundwater-surface water interactions under SGMA. The core goal of this report is to help parties identify and address these questions, and ultimately to let GSAs and stakeholders manage groundwater-surface water interactions proactively and effectively.

Navigating the Growing Prospects and Growing Pains of Managed Aquifer Recharge

National Ground Water Association (NGWA) | November 7th, 2025

Increasing water demands and declining groundwater levels have led to rising interest in managed aquifer recharge. That interest is growing in the United States—the foc

Increasing water demands and declining groundwater levels have led to rising interest in managed aquifer recharge. That interest is growing in the United States—the focus of this article—and elsewhere. Increasing interest makes sense; managed aquifer recharge can reduce water-supply challenges and provide environmental benefits, sometimes with lower costs than alternative water-management approaches. But managed aquifer recharge also faces growing pains, which will make it difficult for projects to scale up and may limit the benefits provided by those projects that do go forward. Some of the problems arise from the challenges of finding physically suitable locations for managed aquifer recharge; many derive from economics, public policy, and law; and some derive from ways in which managed aquifer recharge could exacerbate traditional equity challenges of water management. But as we explain, there also are potential solutions to these challenges, and the future success of managed aquifer recharge will likely depend on the extent to which these solutions are adopted

Navigating Transformations in 2023: The Metropolitan Water District of Southern California Year in Review

Metropolitan Water District of Southern California (MWD) | April 13th, 2024

NAWAPA North American Water and Power Alliance

North American Power and Water Alliance (NAWAPA) | July 1st, 1965

The document is undated and the given date of 1965 is a guess given the timeline on the project. For students of NAWAPA, the Smithsonian Institution has a collection

The document is undated and the given date of 1965 is a guess given the timeline on the project. For students of NAWAPA, the Smithsonian Institution has a collection of archival records

Near-Field Receiving-Water Monitoring of Trace Metals and a Benthic Community Near the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay, California

U.S. Geological Survey (USGS) | November 6th, 2019

Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate co

Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in south San Francisco Bay, Calif. This report includes the data collected by U.S. Geological Survey (USGS) scientists for the period January 2018 to December 2018. These append to long-term datasets extending back to 1974. A major focus of the report is an integrated description of the 2018 data within the context of the longer, multi-decadal dataset. This dataset supports the City of Palo Alto’s Near-Field Receiving-Water Monitoring Program, initiated in 1994. Significant reductions in silver and copper concentrations in both sediment and M. petalum occurred at the site in the 1980s following the implementation by PARWQCP of advanced wastewater treatment and source control measures. Since the 1990s, concentrations of these elements appear to have stabilized at concentrations somewhat above (silver [Ag]) or near (copper [Cu]) regional background concentrations. Data for other metals, including chromium (Cr), mercury (Hg), nickel (Ni), selenium (Se), and zinc (Zn), have been collected since 1994. Over this period, concentrations of these elements have remained relatively constant, aside from seasonal variation that is common to all elements. In 2018, concentrations of silver and copper in M. petalum varied seasonally in response to a combination of site-specific metal exposures and annual growth and reproduction, as reported previously. Seasonal patterns for other elements, including Cr, Ni, Zn, Hg, and Se, were generally similar in timing and magnitude as those for Ag and Cu. This record suggests that legacy contamination and regional-scale factors now largely control sedimentary and bioavailable concentrations of silver and copper, as well as other elements of regulatory interest, at the Palo Alto site. Analyses of the benthic community structure of a mudflat in south San Francisco Bay over a 40-year period show that changes in the community have occurred concurrent with reduced concentrations of metals in the sediment and in the tissues of the biosentinel clam, M. petalum, from the same area. Analysis of M. petalum shows increases in reproductive activity concurrent with the decline in metal concentrations in the tissues of this organism. Reproductive activity is presently stable (2018), with almost all animals initiating reproduction in the fall and spawning the following spring. The entire infaunal community has shifted from being dominated by several opportunistic species to a community where the species are more similar in abundance, a pattern that indicates a more stable community that is subjected to fewer stressors. In addition, two of the opportunistic species (Ampelisca abdita and Streblospio benedicti) that brood their young and live on the surface of the sediment in tubes have shown a continual decline in dominance coincident with the decline in metals; both species had short-lived rebounds in abundance in 2008, 2009, and 2010 and showed signs of increasing abundance in 2018. Heteromastus filiformis (a subsurface polychaete worm that lives in the sediment, consumes sediment and organic particles residing in the sediment, and reproduces by laying its eggs on or in the sediment) showed a concurrent increase in dominance and, in the last several years before 2008, showed a stable population. H. filiformis abundance increased slightly in 2011–2012 and returned to pre-2011 numbers in 2018. An unidentified disturbance occurred on the mudflat in early 2008 that resulted in the loss of the benthic animals, except for deep-dwelling animals like M. petalum. However, within two months of this event, animals returned to the mudflat. The resilience of the community suggested that the disturbance was not caused by a persistent toxin or anoxia. The reproductive mode of most species that were present in 2018 was indicative of species that were available either as pelagic larvae or as mobile adults. Although oviparous species were lower in number in this group, the authors hypothesize that these species will return slowly as more species move back into the area. The use of functional ecology was highlighted in the 2018 benthic community data, which showed that the animals that have now returned to the mudflat are those that can respond successfully to a physical, nontoxic disturbance. Today, community data show a mix of species that consume the sediment, or filter feed, have pelagic larvae that must survive landing on the sediment, and those that brood their young. USGS scientists view the 2008 disturbance event as a response by the infaunal community to an episodic natural stressor (possibly sediment accretion or a pulse of freshwater), in contrast to the long-term recovery from metal contamination. We will compare this recovery to the long-term recovery observed after the 1970s when the decline in sediment pollutants was the dominating factor.

Near-term Colorado River Operations Draft Supplemental Environmental Impact Statement

U.S. Bureau of Reclamation (USBR) | April 11th, 2023

Reclamation is proposing revising the 2007 Interim Guidelines for the near-term operation of Glen Canyon and Hoover Dams beginning in the 2024 operating year (beginning O

Reclamation is proposing revising the 2007 Interim Guidelines for the near-term operation of Glen Canyon and Hoover Dams beginning in the 2024 operating year (beginning October 1, 2023) to address the potential for continued low-runoff conditions in the Basin.

Near-term Colorado River Operations Revised Draft Supplemental Environmental Impact Statement

U.S. Bureau of Reclamation (USBR) | October 26th, 2023

Reclamation is proposing to revise the 2007 Interim Guidelines for the operation of Glen Canyon and Hoover Dams beginning in the 2024 operating year to address the potent

Reclamation is proposing to revise the 2007 Interim Guidelines for the operation of Glen Canyon and Hoover Dams beginning in the 2024 operating year to address the potential for continued low-runoff conditions in the Colorado River Basin. The potential impacts of low runoff conditions in the remainder of the interim period (prior to January 1, 2027) pose unacceptable risks to routine operations of Glen Canyon and Hoover Dams; therefore, modified operating guidelines should be expeditiously developed. Due to size, this file has been divided. Part one, Part two.