Upper San Gabriel Valley Municipal Water District v. City of Alhambra et al

Superior Court of California, County of Los Angeles | June 21st, 2012

Background note from An Evaluation of California’s Adjudicated Groundwater Basins by Langridge et al, (UC Davis) 2016 The Main San Gabriel Basin is one of the larges

Background note from An Evaluation of California’s Adjudicated Groundwater Basins by Langridge et al, (UC Davis) 2016 The Main San Gabriel Basin is one of the largest groundwater basins in southern California, providing residents of the greater San Gabriel Valley with about 240,000 AF per year. It is geographically situated in the south-easterly portion of Los Angeles County and bounded on the north by the San Gabriel Mountains, on the northwest by Raymond Basin, on the southeast by Puente Basin, and on the south by the Central Basin. The adjudication of the basin was deemed necessary by water producers to streamline administration, reduce overdraft, and adhere to the Long Beach Judgment and Puente Narrows Agreements, and the adjudication was relatively amenable. One of the most significant concerns in the basin is water quality, with four areas of the valley containing Superfund sites. The 1973 Judgment included water quality as one of the Watermaster’s responsibilities, and since the mid-1980s the Watermaster has coordinated with regulatory agencies to have groundwater remediation facilities constructed, permitted and operated to protect and enhance the groundwater supplies. The 1992 Judgment amendment explicitly required coordination with EPA for a federal cleanup of the Superfund sites.

Upper San Luis Rey Valley Groundwater Sustainability Plan

Pauma Valley Groundwater Sustainability Agency | January 31st, 2022

The Upper San Luis Rey (USLR) Valley Groundwater Subbasin is a medium-priority basin. As a result, the Pauma Valley GSA was formed and consists of Yuima Municipal Water

The Upper San Luis Rey (USLR) Valley Groundwater Subbasin is a medium-priority basin. As a result, the Pauma Valley GSA was formed and consists of Yuima Municipal Water District (YMWD), Pauma Municipal Water District (Pauma MWD), Pauma Valley Community Services District (CSD), San Luis Rey Municipal Water District (SLRMWD), and the Upper San Luis Rey Resource Conservation District (USLRRCD). The GSA was created to help, not hinder, the effective use of groundwater, and developed this GSP for achieving long-term groundwater sustainability in the basin. The goal of the GSP is to ensure that groundwater continues to be available to everyone who uses it far into the future. Due to size, this file has been divided into three parts. Part 1; Part 2; Part 3

Upper Valley Aquifer Subbasin Groundwater Sustainability Plan

Salinas Valley Basin Groundwater Sustainability Agency | January 13th, 2022

The 2014 California Sustainable Groundwater Management Act (SGMA) requires that medium- and high-priority groundwater basins and subbasins develop Groundwater Sustainabil

The 2014 California Sustainable Groundwater Management Act (SGMA) requires that medium- and high-priority groundwater basins and subbasins develop Groundwater Sustainability Plans (GSPs) that outline how groundwater sustainably will first be maintained for 20 years, and then maintained for an additional 30 years. This GSP fulfills that requirement for the Salinas Valley—Upper Valley Aquifer Subbasin (Subbasin), which is designated by the DWR as a medium priority groundwater subbasin. GSP approved by DWR 4/27/23

Upper Ventura River Valley Basin Groundwater Sustainability Plan

Upper Ventura River Groundwater Agency | January 6th, 2022

The goal of this GSP is to sustainably manage the groundwater resources of the UVRGB for the benefit of current and anticipated future beneficial users of groundwater an

The goal of this GSP is to sustainably manage the groundwater resources of the UVRGB for the benefit of current and anticipated future beneficial users of groundwater and the welfare of the general public who rely directly or indirectly on groundwater. This GSP outlines the approach to achieve and maintain a sustainable groundwater resource free of undesirable results pursuant to the SGMA, while establishing long-term reliability no later than 20 years from GSP adoption. Due to size, this file has been divided into six parts. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6 GSP approved by DWR 4/27/23

Urban Ecological Planning Guide for Santa Clara Valley

San Francisco Estuary Institute (SFEI) | June 20th, 2019

Like most cities, the urbanized region of Santa Clara Valley is a challenging place for plants and animals to make a home. Largely covered with pavement, crisscrossed by

Like most cities, the urbanized region of Santa Clara Valley is a challenging place for plants and animals to make a home. Largely covered with pavement, crisscrossed by major freeways, and fragmented by a variety of land uses, the urban landscape creates barriers to the movement of wildlife and hostile environments for plants. While a small set of species tolerant of cities (such as pigeons and raccoons) can tolerate these difficult conditions, our cities have the potential to support much greater biodiversity. Urban greening projects are already occurring piecemeal across urban landscapes. Harnessing this momentum can help these efforts build greater benefits for biodiversity and for people.  Urban greening projects may take many forms, such as rain gardens beside roadways; bike trails with vegetated medians; planted and expanded riparian vegetation along stream corridors; and landscaping in corporate campuses, municipal parks and private gardens. While often driven by a narrow set of goals such as stormwater capture, public safety, shade, or beautification, these green spaces can be designed and coordinated to support enhanced biodiversity as well. Rain gardens can support native wetland plants, bike trail medians can support ribbons of wildflowers for native insects, street trees can shade pedestrians and provide acorns for birds and squirrels, and stream revegetation or daylighting projects can provide a reflective place for people and strengthen corridors for regional species movement. While each of these types of projects provides benefits, strategically designing these features to reflect ecologically-minded planning, and where possible, coordinating across the landscape, can provide value for humans and nature alike.  This document provides some of the scientific foundation needed to guide planning for urban biodiversity in the Santa Clara Valley region, grounded in an understanding of landscape history, urban ecology and local setting. It can be used to envision the ecological potential for individual urban greening projects, and to guide their siting, design and implementation. It also can be used to guide coordination of projects across the landscape, with the cooperation of a group of stakeholders (such as multiple agencies, cities and counties). Users of this report may include a wide range of entities, such as local nonprofits, public agencies, city planners, and applicants to the Open Space Authority’s Urban Open Space Grant Program.  This document is not intended to inform all aspects of site-specific planning. Much guidance on these topics is already available, and we reference some of those resources here. Rather, it is intended as a companion to existing materials, to inform a broader vision of how such site-scale projects can fit into the larger fabric of the Santa Clara Valley landscape. This document also recommends appropriate habitats and lists of their associated plants for the region, as well as general guidance on practical considerations related to project implementation. 

Urban hydrology and water management— Present and future challenges

Urban Water (Elsevier) | March 1st, 1999

Urban hydrology is an applied science that will have an increasing role to play in the sustainability of human societies. Facing present growth of urban population, it is

Urban hydrology is an applied science that will have an increasing role to play in the sustainability of human societies. Facing present growth of urban population, it is increasingly difficult to find and utilize new sources of water necessary to satisfy growing water demand. For the poor, the residents of peri-urban and squatter areas, an ultimate poverty, the poverty of lacking clean water, is a result. To remove this kind of poverty should be a first priority target for all people and, especially, for people dealing with water management in urban areas. Growth of urban areas brings significant changes in physical properties of land surface increasing integrated vulnerability of inhabitants, agricultural land and rural ecological life supporting systems. Performance of technical solutions depends on climate as well as on social, economical and cultural conditions. Findings from urban hydrological studies based on collection of urban hydrological data, calculations and modeling constitute a necessary fundamental for meaningful water management not only in urban areas but also in entire river basins. Future challenges in urban water management include development of new technical solutions as well as logistic and organizational methods in order to turn present problems into future opportunities. The following current and emerging challenges are discussed in the paper: delivery of drinking water supply for growing cities, water for sanitation versus sanitation without water, recycling of wastewater nutrients, wastewater irrigation, urban agriculture, water to feed depleted aquifers, thoughts about possible future new system solutions, social equity and transfer of knowledge and new technology.

Use of a Three-Dimensional Model for the Analysis of the Ground-Water Flow System in Parker Valley, Arizona and California

U.S. Geological Survey (USGS) | December 1st, 1982

Use of Radiocarbon Ages to Narrow Groundwater Recharge Estimates in the Southeastern Mojave Desert, USA

Hydrology (MDPI) | September 13th, 2018

Estimating groundwater recharge in arid or semiarid regions can be a difficult and complex task, since it is dependent on a highly variable set of spatial and temporal h

Estimating groundwater recharge in arid or semiarid regions can be a difficult and complex task, since it is dependent on a highly variable set of spatial and temporal hydrologic parameters and processes that are dependent on the local climate, the land surface properties, and subsurface characteristics. As a result, traditional methods for estimating the recharge can result in a wide range of derived values. This is evident in the southeastern Mojave Desert, where calculated recharge estimates by previous investigators that range over an order of magnitude (from ~2500 to ~37,000 acre feet per year) are reported. To narrow down this large span of recharge estimates to narrower and more plausible values, this study evaluates the previous recharge estimates in this region, to examine the sources of variability in the reported results and to constrain the recharge estimates based on the hydrologic conditions and the radiocarbon age-dating of spring flows—even without knowledge of the precise subsurface hydrology. The groundwater age and perennial flow characteristics of springs in this study could not be derived from waters sourced solely from local recharge. Therefore, the springs in this study require a significant groundwater contribution to their overall discharge. A previously described conceptual site model in the region established that Bonanza Spring is similarly hydrologically connected to the regional basin-fill aquifer, based on geologic and geochemical/isotopic analyses, and this conceptual site model for where perennial spring water is sourced should readily be extended to these other perennial springs in this region.

User Manual for the California Central Valley Groundwater-Surface Water Simulation Model

California Department of Water Resources (DWR) | June 13th, 2013

This report describes the input and output files for the California Central Valley Groundwater-Surface Water Simulation Model (C2VSim). C2VSim is an integrated numeri

This report describes the input and output files for the California Central Valley Groundwater-Surface Water Simulation Model (C2VSim). C2VSim is an integrated numerical model simulating land surface processes and groundwater and surface water flows in the main alluvial aquifer system of California’s Central Valley (figure 1). C2VSim was developed using the Integrated Water Flow Model (IWFM) application, which couples a three-dimensional finite element groundwater simulation process with one-dimensional land surface, stream flow, lake, unsaturated zone and smallstream watershed simulation processes. The C2VSim version described in this report runs under IWFM version 3.02 and utilizes a coarse grid, and is thus referred to as version 3.02-CG. In addition, the input files for the C2VSim model are regularly updated to correct errors, incorporate improved input data or extend the simulation time period. These updates are referred to as revisions; this report describes the data in revision R374, released in June 2013. The C2VSim model inputs include monthly historical precipitation, stream inflows, surface water diversions, land use and crop acreages for the simulation period, October 1921 through September 2009. C2VSim dynamically calculates crop water demands, allocates contributions from precipitation, soil moisture and surface water diversions, and calculates the groundwater pumpage required to meet the remaining demand. The coarse grid version of the C2VSim model incorporates a finite element grid with 1392 elements, grouped into 21 water budget subregions (figure 1), which are further grouped by drainage basin into five hydrologic regions. The model subregions are based on Depletion Study Areas (DSAs), originally created by the DWR Division of Planning for estimating regional water supplies and demands. Hydrologic parameters (including hydraulic conductivities, storage parameters and recession coefficients) were calibrated to match observed values including groundwater heads, groundwater head differences between well pairs, surface water flows, and stream-groundwater flows for the period between September 1975 and October 2003. The model simulates the historical response of the Central Valley’s groundwater flow system to historical stresses, and can also be used to simulate the response to projected future stresses. Agricultural groundwater pumping is not monitored in the Central Valley, and the C2VSim model provides pumpage estimates that are considered robust because they are constrained spatially and temporally by the estimated demand and surface water supplies. The calibrated model is also being used as the basis for the groundwater flow component of CalSim 3, a water resources planning model for simulating operation of the California State Water Project (SWP) and Federal Central Valley Project (CVP).

Using machine learning to predict 1,2,3-trichloropropane contamination from legacy non-point source pollution of groundwater in California's Central Valley

Elsevier | May 6th, 2023

1,2,3-tricholoropropane (TCP) is an impurity common in nematicides applied to agricultural soils from the 1940s to the 1980s. Evidence from animal studies indicates t

1,2,3-tricholoropropane (TCP) is an impurity common in nematicides applied to agricultural soils from the 1940s to the 1980s. Evidence from animal studies indicates that TCP is a probable human carcinogen. TCP leaches through the soil into groundwater where it persists and contaminates thousands of wells in Asia, Europe, and North America. In California, TCP contaminates drinking water wells, with the highest levels of TCP beneath agricultural land used to grow grapevines. This study performs a mass balance and evaluates the ability of three types of tree-based machine learning models to predict TCP concentration in California's Central Valley aquifer system: classification and regression trees (CART), Random Forest (RF), and Boosted Regression Trees (BRT). To construct the models, multiple spatial explanatory variables were used, including historical agricultural land use data, irrigation levels, precipitation, soil type, groundwater age, redox state, and the presence of the co-contaminant nitrate. To estimate the amount of TCP applied to farmland in California, state historical pesticide and land use documents were used in the mass balance. Between 110,000 and 4,300,000 kg of TCP are estimated to have accumulated in the subsurface. Machine learning models indicate that the most important explanatory variables to predict TCP contamination of groundwater are precipitation, redox state, and the presence of the co-contaminant nitrate. Additionally, a 1000-m buffer area offers a slightly higher predictive performance as compared to 500-m and 1500-m buffers. Furthermore, the RF model outperforms CART and BRT for predictive performance. Finally, modeling using decision trees can predict TCP contamination levels in areas where monitoring is lacking, help target future TCP monitoring efforts, and aid in identifying areas to avoid when drilling new drinking water wells.