Henry Miller Water District Revised Groundwater Sustainability Plan, Kern County Subbasin

Henry Miller Water District | July 21st, 2022

This Groundwater Sustainability Plan (GSP) for the Henry Miller Water District (HMWD) Groundwater Sustainability Agency (GSA) has been prepared pursuant to Water Code §1

This Groundwater Sustainability Plan (GSP) for the Henry Miller Water District (HMWD) Groundwater Sustainability Agency (GSA) has been prepared pursuant to Water Code §10727. HMWD is located in the Kern County Subbasin (Basin 5-22.14) as defined by the Department of Water Resources’ (DWR) Bulletin 118. The Kern Subbasin is considered to be in a condition of critical overdraft and has been designated as a high priority basin. This GSP is one of the five GSPs being prepared in the Subbasin, which collectively has and will coordinate to avoid, to the best of their abilities, any and all Undesirable Results as a result of unsustainable groundwater management practices. HMWD formed its own GSA on March 15, 2017; it is the only Water District located within the GSA. HMWD GSA is one of five GSAs that are preparing a GSP within the Subbasin. This GSP, in coordination with the four other GSPs within the Subbasin, will provide a path to sustainability and the preservation of groundwater resources for all beneficial users of groundwater. Because the Subbasin has multiple GSPs, the GSPs are prepared under a coordination agreement. This Coordination Agreement exemplifies the ways that the various GSPs were able to work together to achieve a common goal: groundwater sustainability for the Subbasin. For example, the entire Subbasin has utilized Todd Groundwater’s services to analyze historic, current, and future groundwater conditions with a C2VSIM model. This Plan includes a description of the historic groundwater conditions in the Subbasin, a Subbasin water budget, sustainable management criteria for future monitoring, and projects and/or management actions that may be implemented to ensure groundwater sustainability is achieved by 2040 and maintained through 2070. Due to size, the file has been divided. Part 1, Part 2, Part 3, Part 4, Part 5

Heresy in ENSO teleconnections: Atmospheric rivers as disruptors of canonical seasonal precipitation anomalies in the Southwestern US

Springer Nature | February 7th, 2025

In spite of forecasts for anomalous dryness based on the canonical La Niña signal, Water Years 2011, 2017, and 2023 brought copious precipitation to California and the S

In spite of forecasts for anomalous dryness based on the canonical La Niña signal, Water Years 2011, 2017, and 2023 brought copious precipitation to California and the Southwestern United States (SWUS). Although El Niño–Southern Oscillation (ENSO) is the main source of seasonal precipitation predictability for the region, outstanding Atmospheric River (AR) activity produced the unexpected regional wetness in each of these heretical water years (WYs). We define heretical WYs as those that result in precipitation anomalies that oppose those expected based on ENSO canon. We assess the contribution of ARs and other storms to these WYs, finding that heretical La Niña/El Niño WYs were characterized by anomalously robust/deficient AR activity. In California, precipitation accumulation during the heretical La Niña WYs was comparable to or even exceeded that observed during the exceedingly wet WY1998—the textbook canonical El Niño year. Our findings indicate a weaker/stronger relationship between ENSO and AR/non-AR precipitation, primarily driven by storm frequency. Although ARs can disrupt the ENSO-precipitation signal, ENSO still influences the frequency of AR precipitation in the southwestern U.S. desert, the region influenced by ARs that make landfall in Baja California, Mexico. These results highlight the complexity of ENSO's impact on precipitation in the Western US and underscore the need for a nuanced understanding of ENSO’s influence on ARs to improve seasonal precipitation prediction.

High-elevation snowpack loss during the 2021 Pacific Northwest heat dome amplified by successive spring heatwaves

Nature Portfolio (Springer Nature) | December 13th, 2023

High-resolution mapping of global surface water and its long-term changes

Nature Portfolio (Springer Nature) | December 7th, 2016

The location and persistence of surface water (inland and coastal) is both affected by climate and human activity and affects climate, biological diversity and hu

The location and persistence of surface water (inland and coastal) is both affected by climate and human activity and affects climate, biological diversity and human wellbeing. Global data sets documenting surface water location and seasonality have been produced from inventories and national descriptions, statistical extrapolation of regional data and satellite imagery, but measuring long-term changes at high resolution remains a challenge. Here, using three million Landsat satellite images, we quantify changes in global surface water over the past 32 years at 30-metre resolution. We record the months and years when water was present, where occurrence changed and what form changes took in terms of seasonality and persistence. Between 1984 and 2015 permanent surface water has disappeared from an area of almost 90,000 square kilometres, roughly equivalent to that of Lake Superior, though new permanent bodies of surface water covering 184,000 square kilometres have formed elsewhere. All continental regions show a net increase in permanent water, except Oceania, which has a fractional (one per cent) net loss. Much of the increase is from reservoir filling, although climate change is also implicated. Loss is more geographically concentrated than gain. Over 70 per cent of global net permanent water loss occurred in the Middle East and Central Asia, linked to drought and human actions including river diversion or damming and unregulated withdrawal. Losses in Australia17 and the USA18 linked to long-term droughts are also evident. This globally consistent, validated data set shows that impacts of climate change and climate oscillations on surface water occurrence can be measured and that evidence can be gathered to show how surface water is altered by human activities. We anticipate that this freely available data will improve the modelling of surface forcing, provide evidence of state and change in wetland ecotones (the transition areas between biomes), and inform water-management decision-making.

High‐resolution surface water dynamics in Earth’s small and medium‐sized reservoirs

Nature Portfolio (Springer Nature) | August 12th, 2022

Small and medium‐sized reservoirs play an important role in water systems that need to cope with climate variability and various other man‐made and natural challenges

Small and medium‐sized reservoirs play an important role in water systems that need to cope with climate variability and various other man‐made and natural challenges. Although reservoirs and dams are criticized for their negative social and environmental impacts by reducing natural flow variability and obstructing river connections, they are also recognized as important for social and economic development and climate change adaptation. Multiple studies map large dams and analyze the dynamics of water stored in the reservoirs behind these dams, but very few studies focus on small and medium‐sized reservoirs on a global scale. In this research, we use multi‐annual multi‐sensor satellite data, combined with cloud analytics, to monitor the state of small (10–100 ha) to medium‐ sized (> 100 ha, excluding 479 large ones) artificial water reservoirs globally for the first time. These reservoirs are of crucial importance to the well‐being of many societies, but regular monitoring records of their water dynamics are mostly missing. We combine the results of multiple studies to identify 71,208 small to medium‐sized reservoirs, followed by reconstructing surface water area changes from satellite data using a novel method introduced in this study. The dataset is validated using 768 daily in‐situ water level and storage measurements (r2 > 0.7 for 67% of the reservoirs used for the validation) demonstrating that the surface water area dynamics can be used as a proxy for water storage dynamics in many cases. Our analysis shows that for small reservoirs, the inter‐annual and intra‐annual variability is much higher than for medium‐sized reservoirs worldwide. This implies that the communities reliant on small reservoirs are more vulnerable to climate extremes, both short‐term (within seasons) and longer‐term (across seasons). Our findings show that the long‐term inter‐annual and intra‐annual changes in these reservoirs are not equally distributed geographically. Through several cases, we demonstrate that this technology can help monitor water scarcity conditions and emerging food insecurity, and facilitate transboundary cooperation. It has the potential to provide operational information on conditions in ungauged or upstream riparian countries that do not share such data with neighboring countries. This may help to create a more level playing field in water resource information globally.

Historical and future relations between large storms and droughts in California

University of California, Davis (UC Davis) | July 14th, 2016

California precipitation varies more dramatically from year to year than elsewhere in the conterminous United States. This paper analyzes the extent to which contribution

California precipitation varies more dramatically from year to year than elsewhere in the conterminous United States. This paper analyzes the extent to which contributions of the wettest days to overall precipitation dictate the state’s precipitation seasonality and frequent multiyear periods of drought (as precipitation deficit) and plenty is analyzed, historically and in projections of future climates. The wettest 5% of wet days in California contribute about a third of precipitation but about two-thirds of the variance of water-year precipitation. Year-to-year fluctuations in precipitation strongly reflect year-to-year fluctuations of contributions from the largest storms, with the large-storm contributions explaining about twice as much precipitation fluctuation as do contributions from all remaining storms combined. This extreme dominance of large storms is largely unique to California within the United States. In climate-change projections, eight of ten climate models considered here yield increases in precipitation from the largest storms, and when the increases are large, total precipitation follows suit. All of the models project declines in contributions from the smaller storms and models projecting total-precipitation declines reflect this decline. Projected changes in variance of water-year precipitation reflect changes in variance of large-storm contributions. The disproportionately large overall contributions from California’s largest storms, and their outsized year-to-year variability, ensure that the state’s largest storms dictate the state’s regimes of wet and dry spells, historically and in climate-change projections.

Hot Drought of Summer 2023 in Southwestern North America

American Geophysical Union (AGU) | September 17th, 2025

Hot droughts, or compound drought and heatwaves, have a significant impact on arid regions in southwestern North America (SWNA). In the summer of 2023, SWNA experienced u

Hot droughts, or compound drought and heatwaves, have a significant impact on arid regions in southwestern North America (SWNA). In the summer of 2023, SWNA experienced unusually intense hot droughts during both the daytime and nighttime, with their severity amplified three to five times above values during the prior four decades. Over this period, a significant increase was found in the coupling between nighttime and daytime conditions at local scales and across different regions of the SWNA. The hot drought was due to a suppressed North American monsoon (NAM) in response to synoptic-scale subsidence and moisture divergence. Nevertheless, we identified a remote connection between soil moisture in upwind areas and hot drought conditions in downwind regions across the US-Mexico border. Our findings indicate that hot droughts need to be analyzed over complete diurnal cycles and over regions that are connected through atmospheric pathways to improve their prediction, response, and mitigation.

Hourly storm characteristics along the U.S. West Coast: Role of atmospheric rivers in extreme precipitation

American Geophysical Union (AGU) | June 21st, 2017

Gridded hourly precipitation observations over the conterminous U.S., from 1948 to 2002, are analyzed to determine climatological characteristics of storm precipitation t

Gridded hourly precipitation observations over the conterminous U.S., from 1948 to 2002, are analyzed to determine climatological characteristics of storm precipitation totals. Despite generally lower hourly intensities, precipitation totals along the U.S. West Coast (USWC) are comparable to those in southeast U.S. (SEUS). Storm durations, more so than hourly intensities, strongly modulate precipitation-total variability over the USWC, where the correlation coefficients between storm durations and storm totals range from 0.7 to 0.9. Atmospheric rivers (ARs) contribute 30–50% of annual precipitation on the USWC and make such large contributions to extreme storms that 60–100% of the most extreme storms, i.e., storms with precipitation-total return intervals longer than 2 years, are associated with ARs. These extreme storm totals are more strongly tied to storm durations than to storm hourly or average intensities, emphasizing the importance of AR persistence to extreme storms on the USWC.

How are Western water districts managing groundwater basins?

California Agriculture (UCANR) | March 13th, 2018

Making the transition from open-access groundwater rights to sustainable groundwater management is a formidable task for newly formed groundwater sustainability agencies

Making the transition from open-access groundwater rights to sustainable groundwater management is a formidable task for newly formed groundwater sustainability agencies in California. As agencies begin to decide how to make equitable water allocations, how to monitor groundwater use and what mix of supply- and demand-side mechanisms to adopt to satisfy sustainability criteria, the groundwater management strategies in place across other basins in the western United States are worth studying. We surveyed 18 groundwater districts in California and other Western states to identify the management approaches and practices they have instituted. The conclusions we draw suggest a correlative rights framework of water allocation with phase-ins for heavy users; metered pumping; flexible arrangements for trading and carrying over allocations for multiple years; and incentivizing groundwater recharge, including recharge from deep percolation from crops. Rigid formulas for significantly reducing groundwater use in medium- and high-priority basins are likely to have significant negative effects on the regional economy.

How are Western water districts managing groundwater basins?

California Agriculture (UCANR) | March 13th, 2018

Making the transition from open-access groundwater rights to sustainable groundwater management is a formidable task for newly formed groundwater sustainability age

Making the transition from open-access groundwater rights to sustainable groundwater management is a formidable task for newly formed groundwater sustainability agencies in California. As agencies begin to decide how to make equitable water allocations, how to monitor groundwater use and what mix of supply- and demand-side mechanisms to adopt to satisfy sustainability criteria, the groundwater management strategies in place across other basins in the western United States are worth studying. We surveyed 18 groundwater districts in California and other Western states to identify the management approaches and practices they have instituted. The conclusions we draw suggest a correlative rights framework of water allocation with phase-ins for heavy users; metered pumping; flexible arrangements for trading and carrying over allocations for multiple years; and incentivizing groundwater recharge, including recharge from deep percolation from crops. Rigid formulas for significantly reducing groundwater use in medium- and high-priority basins are likely to have significant negative effects on the regional economy.