Westside Subbasin Groundwater Sustainability Plan

Westlands Water District | January 23rd, 2020

Westside Subbasin Groundwater Sustainability Plan (Clarified and Amended GSP)

Westlands Water District | July 18th, 2022

Due to size, this file has been divided into 11 parts. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9, Part 10, Part 11

Due to size, this file has been divided into 11 parts. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9, Part 10, Part 11

Wet Antecedent Soil Moisture Increases Atmospheric River Streamflow Magnitudes Nonlinearly

American Meteorological Society (AMS) | June 4th, 2025

Atmospheric rivers (ARs) drive most riverine floods on the U.S. West Coast. However, estimating flood risk based solely on AR intensity and duration is challenging becaus

Atmospheric rivers (ARs) drive most riverine floods on the U.S. West Coast. However, estimating flood risk based solely on AR intensity and duration is challenging because precipitation phase, antecedent conditions, and physical watershed characteristics (e.g., slope and soil depth) can influence the magnitude of floods. Here, we analyze how antecedent soil moisture (ASM) conditions contribute to variability in streamflow during AR events and how that changes across climatic regimes and physiography in 122 U.S. West Coast watersheds. We identify a robust nonlinear relationship between streamflow and ASM during ARs in 89% of watersheds. The inflection point in this relationship represents a watershed-specific critical ASM threshold, above which event maximum streamflow is, on average, 2–4.5 times larger. Wet ASM conditions amplify the hydrologic impacts of more frequent but weaker, lower moisture transport AR events, while dry ASM conditions attenuate the hydrologic impacts that stronger, higher moisture transport AR events could otherwise cause. Our research shows that watersheds prone to ASM-amplified streamflows have higher evaporation ratios, lower cold-season precipitation, lower snow-to-rain ratios, and shallower, clay-rich soils. Higher evaporation and lower precipitation lead to greater ASM variability during the cold season, increasing streamflow during wet periods and buffering streamflow during dry periods. Lower snow fraction and shallower soils limit the antecedent water storage capacity of a watershed, contributing to greater sensitivity of streamflow peaks to ASM variability. Incorporating ASM thresholds into hydrologic models in these regions prone to AR-amplified streamflow could improve forecasts and decrease uncertainty.

What Threat Does Sea-Level Rise Pose to California?

Legislative Analyst's Office (LAO) | August 10th, 2020

Among Its Other Challenges, California Continues to Face the Looming Impacts of Climate Change and Rising Seas. While the coronavirus disease 2019 (COVID‑19) pandemic a

Among Its Other Challenges, California Continues to Face the Looming Impacts of Climate Change and Rising Seas. While the coronavirus disease 2019 (COVID‑19) pandemic and resulting economic impacts have rightly drawn the focus of the Legislature’s and public’s attention since March 2020, other statewide challenges continue to approach on the horizon. Among these are the impending impacts of climate change, including the hazards that rising seas pose to California’s coast. Scientific estimates suggest the magnitude of sea‑level rise (SLR) in California could be at least half of one foot in 2030 and as much as seven feet by 2100. Moreover, storm surges, exceptionally high “king tides,” or El Niño events could produce notably higher water levels than SLR alone.

White Wolf Subbasin Technical Report

Wheeler Ridge-Maricopa Water Storage District | March 16th, 2016

The purpose of the White Wolf Subbasin Technical Study (Study) is to support the basin boundary modification request (Request) being jointly submitted to DWR by Wheeler-R

The purpose of the White Wolf Subbasin Technical Study (Study) is to support the basin boundary modification request (Request) being jointly submitted to DWR by Wheeler-Ridge Maricopa Water Storage District (WRMWSD), Arvin-Edison Water Storage District (AEWSD), and Tejon-Castac Water District (TCWD) (collectively referred to as the Districts), in accordance with the Basin Boundary Emergency Regulations. Request is a scientific request that involves the subdivision of the Kern County Subbasin of the San Joaquin Valley Groundwater Basin (DWR Basin 5-22.14) into two separate subbasins: the Kern County Subbasin and the White Wolf Subbasin (Subbasin). As shown on Figure 1, the proposed revision divides the subbasins along the White Wolf Fault (WWF), relying upon scientific evidence that demonstrates that the WWF provides a significant impediment to groundwater flow.

Widespread and increased drilling of wells into fossil aquifers in the USA

Nature Portfolio (Springer Nature) | April 19th, 2022

Most stored groundwater is ‘fossil’ in its age, having been under the ground for more than ~12 thousand years. Mapping where wells tap fossil aquifers is relevant for

Most stored groundwater is ‘fossil’ in its age, having been under the ground for more than ~12 thousand years. Mapping where wells tap fossil aquifers is relevant for water quality and quantity management. Nevertheless, the prevalence of wells that tap fossil aquifers is not known. Here we show that wells that are sufficiently deep to tap fossil aquifers are widespread, though they remain outnumbered by shallower wells in most areas. Moreover, the proportion of newly drilled wells that are deep enough to tap fossil aquifers has increased over recent decades. However, this widespread and increased drilling of wells into fossil aquifers is not necessarily associated with groundwater depletion, emphasizing that the presence of fossil groundwater does not necessarily indicate a non-renewable water supply. Our results highlight the importance of safeguarding fossil groundwater quality and quantity to meet present and future water demands.

Widespread aquifer depressurization after a century of intensive groundwater use in USA

American Association for the Advancement of Science (AAAS) | September 15th, 2023

Widespread potential loss of streamflow into underlying aquifers across the USA

Nature Portfolio (Springer Nature) | March 17th, 2021

Most rivers exchange water with surrounding aquifers. Where groundwater levels lie below nearby streams, streamwater can infiltrate through the streambed, reducing stream

Most rivers exchange water with surrounding aquifers. Where groundwater levels lie below nearby streams, streamwater can infiltrate through the streambed, reducing streamflow and recharging the aquifer. These ‘losing’ streams have important implications for water availability, riparian ecosystems and environmental flows, but the prevalence of losing streams remains poorly constrained by continent-wide in situ observations. Here we analyse water levels in 4.2 million wells across the contiguous USA and show that nearly two-thirds (64 per cent) of them lie below nearby stream surfaces, implying that these streamwaters will seep into the subsurface if it is sufficiently permeable. A lack of adequate permeability data prevents us from quantifying the magnitudes of these subsurface flows, but our analysis nonetheless demonstrates widespread potential for streamwater losses into underlying aquifers. These potentially losing rivers are more common in drier climates, flatter landscapes and regions with extensive groundwater pumping. Our results thus imply that climatic factors, geological conditions and historic groundwater pumping jointly contribute to the widespread risk of streams losing flow into surrounding aquifers instead of gaining flow from them. Recent modelling studies have suggested that losing streams could become common in future decades, but our direct observations show that many rivers across the USA are already potentially losing flow, highlighting the importance of coordinating groundwater and surface water policy.

Wright et al v. Goleta Water District

Superior Court of California, County of Santa Barbara | November 17th, 1989

Wyandotte Creek Groundwater Subbasin Groundwater Sustainability Plan

Wyandotte Creek Groundwater Sustainability Agency | December 15th, 2021

The Wyandotte Creek Subbasin lies in the eastern central portion of the Sacramento Groundwater Basin. It is bounded on the west by the Feather River and Thermalito After

The Wyandotte Creek Subbasin lies in the eastern central portion of the Sacramento Groundwater Basin. It is bounded on the west by the Feather River and Thermalito Afterbay; in the south by the Butte-Yuba County line (except for Ramirez Water District which is fully within the North Yuba Subbasin); and on the north and east by the edge of the alluvial basin as defined by DWR Bulletin 118 - Update 2003 (DWR, 2003). It is surrounded by the Butte Subbasin to the west, the Wyandotte Creek Subbasin to the north, the North Yuba Subbasin to the south and the foothills to the east (Figure ES-2). The lateral boundaries of the Wyandotte Creek Subbasin are jurisdictional in nature, and it is recognized that groundwater flows across each of the defined boundaries to some degree.