Midcoast Groundwater Study Phase III, San Mateo County, California

San Mateo County | June 4th, 2010

San Mateo County ‘Midcoast’ extends from northern Half Moon Bay to Devils Slide along Highway 1. It encompasses the communities of Montara, Moss Beach, Seal Cove, Pri

San Mateo County ‘Midcoast’ extends from northern Half Moon Bay to Devils Slide along Highway 1. It encompasses the communities of Montara, Moss Beach, Seal Cove, Princeton, El Granada, and Miramar. Domestic water is supplied to the southern part of the region by Coastside County Water District (CCWD), providing services from Half Moon Bay to Princeton, and by Montara Water and Sanitary District (MWSD) on the north, servicing Montara and Moss Beach. Private wells are scattered through both service districts and outlying areas. With the exception of CCWD, which meets much of its demand through long-term contractual agreements with San Francisco Public Utilities Commission, the source of domestic water is from local surface water and groundwater resources. The carrying capacity of the local resources may be considered as the population that can be sustained using conservation measures during an extended drought without undue stress to valued natural habitats.

Modeling the dynamic penetration depth of post-1950s water in unconfined aquifers using environmental tracers: Central Valley, California

Journal of Hydrology (Elsevier) | December 5th, 2022

The penetration depth of post-1950s recharge (D-1950) in aquifers is a marker that is frequently used to identify groundwater that is susceptible to anthropogenic contami

The penetration depth of post-1950s recharge (D-1950) in aquifers is a marker that is frequently used to identify groundwater that is susceptible to anthropogenic contamination. Here, we compute D-1950 values at wells, interpolate them in space, and project them across time to map the moving front of modern recharge in four dimensions in the Central Valley aquifer system, California, USA. Tracers of groundwater age (tritium, carbon-14, noble gases, sulfur hexafluoride, and chlorofluorocarbons) were collected at 650 wells spatially distributed throughout the Central Valley and were fit to a lumped-parameter model that assumes a logarithmic age-depth profile in the aquifer. For samples where tritium was present (>0.3 tritium units), the model was used to predict D-1950 at wells screened above or across the modern-premodern interface (n = 484). Wells with samples where tritium was absent (≤0.3 tritium units) were used to define the depth beyond which groundwater is completely premodern (n = 166). Predicted D-1950 values were below the depth of screen bottoms for wells where groundwater is completely modern, and above the depth of screen tops for wells where groundwater is completely premodern. The interpolated surface of D-1950 is dynamic, less prone to extreme values, and produces maps with lower interpolation errors due to a higher spatial density of wells than maps based on the depth of premodern groundwater. Between 2005 and 2025, D-1950 is expected to deepen by 11 and 12 m in the northern and southern parts of the Central Valley, respectively. Areas where D-1950 increases rapidly are likely to see increases in nitrate and other anthropogenic contaminants associated with the downward moving front of modern water.

Modesto Subbasin Groundwater Sustainability Plan

Stanislaus and Tuolumne Rivers Groundwater Basin Association (STRGBA) | January 31st, 2022

This Groundwater Sustainability Plan (GSP) covers the entire Modesto Subbasin (5-22.02), designated a high-priority basin by the Department of Water Resources (DWR). The

This Groundwater Sustainability Plan (GSP) covers the entire Modesto Subbasin (5-22.02), designated a high-priority basin by the Department of Water Resources (DWR). The Modesto Subbasin covers about 245,253 acres in the northern San Joaquin Valley Groundwater Basin and is bounded by the Stanislaus River on the north, the Tuolumne River on the south, the San Joaquin River on the west and the crystalline basement rocks of the Sierra Nevada Foothills on the east. The Modesto Subbasin relies on two primary sources of water supply – surface water from the Stanislaus and Tuolumne rivers and groundwater pumped from the Subbasin. Due to size, this file has been divided. Part 1, Part 2, Part 3, Part 4

Modesto Subbasin Groundwater Sustainability Plan (Revised)

Publisher not available | July 12th, 2024

Submitted to the Department of Water Resources (DWR) in January 2022, the first version of this GSP was reviewed by DWR in January 2024 and determined to be incomplete (D

Submitted to the Department of Water Resources (DWR) in January 2022, the first version of this GSP was reviewed by DWR in January 2024 and determined to be incomplete (DWR, 2024). Two deficiencies were identified by DWR. The first of these involves provision of sufficient information (namely, analysis of potential impacts on wells) to support the selection of sustainable management criteria for chronic lowering of groundwater levels. The second involves provision of sufficient details on the projects and management actions to mitigate overdraft in the Subbasin and provide a feasible path to achieve sustainability. Corrective actions, including a resolution approved by both GSAs to arrest groundwater level declines by 2027 and raise groundwater levels after 2027, are incorporated into this revised July 16, 2024, GSP for resubmittal to DWR. This GSP is a revised version and does not represent a GSP update, which is slated for 2027. Due to size, this file has been divided. Part 1, Part 2, Part 3, Part 4

Moisture vs. Wind-Dominated Flavors of Atmospheric Rivers

American Geophysical Union (AGU) | November 20th, 2020

Atmospheric rivers (ARs) are essential features of the global water cycle. Although AR definitions are commonly based on integrated vapor transport (IVT), ARs of a given

Atmospheric rivers (ARs) are essential features of the global water cycle. Although AR definitions are commonly based on integrated vapor transport (IVT), ARs of a given IVT can induce a wide range of surface precipitation and wind impacts. We develop an AR “flavor” metric that partitions AR IVT into moisture-dominant and wind-dominant components. We use this metric to create a climatological catalog of “wet” and “windy” ARs along the U.S. West Coast from 1980 to 2016. Windy ARs are generally associated with stronger surface winds than are wet ARs, with the largest differences at low IVT. Windy ARs are also associated with greater daily precipitation totals than are wet ARs, with the difference widening at higher IVT, notably over mountainous regions. Pacific Northwest ARs have become increasingly moisture dominated over 1980–2016, which has important implications for western U.S. water availability and flood risk.

Mojave Water Agency 2004 Regional Water Management Plan

Mojave Water Agency (MWA) | December 8th, 2005

This document supplements the Urban Water Management Plan element of the Mojave Water Agency (MWA) 2004 Regional Water Management Plan (RWMP). The RWMP is the master pl

This document supplements the Urban Water Management Plan element of the Mojave Water Agency (MWA) 2004 Regional Water Management Plan (RWMP). The RWMP is the master plan for MWA water management activities through the year 2020. This update provides additional information to meet 2005 Urban Water Management Plan update requirements, especially a projection of supply and demand through at least 2025. The 2005 Urban Water Management Plan is fully described in the 2004 RWMP as updated by this supplement with supply and demand projections through 2030.

Montecito Groundwater Basin Groundwater Sustainability Plan

Montecito Groundwater Basin Groundwater Sustainability Agency (MGBGSA) | May 19th, 2023

More extreme precipitation in the world's dry and wet regions

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

Intensification of the hydrological cycle is expected to accompany a warming climate. It has been suggested that changes in the spatial distribution of precipitation will

Intensification of the hydrological cycle is expected to accompany a warming climate. It has been suggested that changes in the spatial distribution of precipitation will amplify differences between dry and wet regions, but this has been disputed for changes over land. Furthermore, precipitation changes may differ not only between regions but also between different aspects of precipitation, such as totals and extremes. Here we investigate changes in these two aspects in the world’s dry and wet regions using observations and global climate models. Despite uncertainties in total precipitation changes, extreme daily precipitation averaged over both dry and wet regimes shows robust increases in both observations and climate models over the past six decades. Climate projections for the rest of the century show continued intensification of daily precipitation extremes. Increases in total and extreme precipitation in dry regions are linearly related to the model-specific global temperature change, so that the spread in projected global warming partly explains the spread in precipitation intensification in these regions by the late twenty-first century. This intensification has implications for the risk of flooding as the climate warms, particularly for the world’s dry regions.

Moving Forward Effort: Phase 1 Report

U.S. Bureau of Reclamation (USBR) | May 1st, 2015

In 2012, the Bureau of Reclamation (Reclamation), in partnership with the seven Colorado River Basin States (Basin States) and in collaboration with a wide spectrum of

In 2012, the Bureau of Reclamation (Reclamation), in partnership with the seven Colorado River Basin States (Basin States) and in collaboration with a wide spectrum of Colorado River Basin (Basin) stakeholders, published the most comprehensive study of future Basin supply and demand ever undertaken. The Colorado River Basin Water Supply and Demand Study (Basin Study) confirmed that, in the absence of timely action, there are likely to be significant shortfalls between projected water supplies and demands in coming decades. The Basin Study also confirmed that a wide range of solutions are needed to mitigate and adapt to such shortfalls, which are likely to affect each sector (agricultural, municipal, energy, and environmental, for example) dependent on the Colorado River and its tributaries. In response to the findings of the Basin Study, in May 2013, Reclamation and the Basin States, in collaboration with the Ten Tribes Partnership and conservation organizations, initiated the Moving Forward effort to build on future considerations and next steps identified in the Basin Study. The Moving Forward effort builds upon and enhances the broad, inclusive stakeholder process demonstrated in the Basin Study with an ultimate goal of identifying actionable steps to address projected water supply and demand imbalances that have broad-based support and provide a wide-range of benefits. The Moving Forward effort is being conducted in a phased approach. Phase 1, which was funded by Reclamation and the Basin States, began with the formation of a Coordination Team and three multi-stakeholder workgroups that focus on water conservation, reuse, and environmental and recreational flows. The Phase 1 Report documents the activities and outcomes of the workgroups during this phase. Commenting on the information provided in the Phase 1 Report is encouraged. Written comments should be submitted within 90 days following the release of this report. The comments will be summarized and posted to the Moving Forward website and will be considered in future Moving Forward phases. Instructions for submitting comments are provided at [this link].

Multi-year predictability of climate, drought, and wildfire in southwestern North America

Nature Portfolio (Springer Nature) | July 26th, 2017

Past severe droughts over North America have led to massive water shortages and increases in wildfire frequency. Triggering sources for multi-year droughts in this region

Past severe droughts over North America have led to massive water shortages and increases in wildfire frequency. Triggering sources for multi-year droughts in this region include randomly occurring atmospheric blocking patterns, ocean impacts on atmospheric circulation, and climate’s response to anthropogenic radiative forcings. A combination of these sources translates into a difficulty to predict the onset and length of such droughts on multi-year timescales. Here we present results from a new multi-year dynamical prediction system that exhibits a high degree of skill in forecasting wildfire probabilities and drought for 10–23 and 10–45 months lead time, which extends far beyond the current seasonal prediction activities for southwestern North America. Using a state-of-the-art earth system model along with 3-dimensional ocean data assimilation and by prescribing the external radiative forcings, this system simulates the observed low-frequency variability of precipitation, soil water, and wildfire probabilities in close agreement with observational records and reanalysis data. The underlying source of multi-year predictability can be traced back to variations of the Atlantic/Pacific sea surface temperature gradient, external radiative forcings, and the low-pass filtering characteristics of soils.