South Coast

Salt and Nutrient Management Plan Santa Clara River Valley East Subbasin

California State Water Resources Control Board (SWRCB) | October 25th, 2016

In accordance with the State Water Resources Control Board’s (SWRCB’s) Recycled Water Policy, the Upper Santa Clara River Integrated Regional Water Management Group

In accordance with the State Water Resources Control Board’s (SWRCB’s) Recycled Water Policy, the Upper Santa Clara River Integrated Regional Water Management Group (IRWMG), which is comprised of Castaic Lake Water Agency (CLWA), City of Santa Clarita, CLWA Santa Clarita Water Division (SCWD), Los Angeles County Flood Control District (LACFCD), Newhall County Water District (NCWD), San Gabriel & Lower Los Angeles Rivers and Mountains Conservancy, Santa Clarita Valley Sanitation District (SCVSD) and Valencia Water Company (VWC), have entered into a Memorandum of Understanding (MOU) to prepare a Salt and Nutrient Management Plan (SNMP) for the Santa Clara River Valley East Groundwater Subbasin (East Subbasin). This group of agencies, collectively known as the SNMP Task Force (Task Force) and facilitated by the CLWA, have directed the preparation of this SNMP, which was prepared using guidance set forth by the Los Angeles Regional Water Quality Control Board (LARWQCB). The purpose of this SNMP is to determine the current (ambient) water quality conditions in the East Subbasin and to ensure that all water management practices, including the use of recycled water, are consistent with water quality objectives. This SNMP is intended to provide the framework for water management practices to ensure protection of beneficial uses, and allow for the sustainability of groundwater resources consistent with the Water Quality Control Plan Los Angeles Region (Basin Plan). Additionally, compliance with the California Environmental Quality Act (CEQA) and approval by LARWQCB staff is required. As part of the SNMP, a monitoring plan has been developed for the East Subbasin which identifies key monitoring locations within each subunit for both surface water and groundwater.

Salton Sea Exceedances of California’s Air-Quality Standards Highlight Governance Gaps and Monitoring Needs

University of California, Los Angeles (UCLA) | September 4th, 2025

The Salton Sea region is known for its poor air-quality, which is often linked to dust and contributes to alarmingly high rates of respiratory problems among residents. H

The Salton Sea region is known for its poor air-quality, which is often linked to dust and contributes to alarmingly high rates of respiratory problems among residents. However, air-quality issues extend beyond dust. Residents also face the distressing reality of frequent hydrogen sulfide (H2S) emissions. Depending on individual experiences, these emissions can range from uncomfortable to severely suffocating. To gauge the severity of these concerns, the Salton Sea Environmental Timeseries (SSET), a community-based research group, recently installed two hydrogen sulfide monitors in the area. Their data indicates that H₂S emissions consistently exceed the California Air Resources Board state standard of 30 parts per billion (ppb), with 243 hours above this threshold recorded between May and September 2024 alone. Existing government air-quality monitors, located north of the Salton Sea, primarily detect H₂S only when winds blow from the southeast, whereas SSET data show elevated emissions occur regardless of wind direction. This highlights a critical gap in the current government monitoring network, which fails to capture the full scope of H₂S pollution. As more data highlight connections between water and air-quality, it is crucial to monitor air-quality in all its aspects, not just those related to dust. The Salton Sea region has a predominantly low-income Latinx, immigrant, and Indigenous population across two California counties. The persistent issue of hydrogen sulfide pollution serves as a clear example of environmental injustice. For over two decades, the state and federal governments have been legally obligated to restore the Salton Sea—meeting that obligation today means pairing public health action with robust monitoring.

Salton Sea Monitoring Implementation Program (MIP) Annual Work Plan 2024

California Natural Resources Agency (CNRA) | February 29th, 2024

The California Natural Resources Agency (CNRA), the California Department of Water Resources (DWR), and the California Department of Fish and Wildlife (CDFW) are implemen

The California Natural Resources Agency (CNRA), the California Department of Water Resources (DWR), and the California Department of Fish and Wildlife (CDFW) are implementing the Salton Sea Management Program (SSMP) to address air quality and ecological threats at the Salton Sea. The SSMP has a plan for action over the 10-year period from 2018 to 2028 (Phase 1: 10-Year Plan), which aims to improve conditions around the Salton Sea by constructing projects that create habitat and reduce dust from the exposed lakebed on 30,000 acres. Since the state is not a significant landowner in the area, collaboration with land-owning entities is essential and a top priority for the SSMP. The SSMP team also recognizes the crucial role of partnerships in meeting restoration goals through collecting data, facilitating project implementation, and helping obtain funding sources. The Salton Sea Monitoring Implementation Plan (MIP) is a regional-scale monitoring plan for the Salton Sea ecosystem (CNRA 2022). The MIP, which was developed with input from implementing partners (agencies, non-governmental activities to measure conditions of water, air quality, land cover, biological resources, and socioeconomics. The MIP prioritized indicators and metrics and summarized methods and sampling regimes. These indicators were prioritized based on their informativeness and relationship to key resources and drivers of the Salton Sea ecosystem, feasibility of measurement, and relevance for management actions. Some indicators were recommended only for focused study to inform a specific management-articulated information need or specifically identified data gap.

Saltwater Intrusion in Los Angeles Area Coastal Aquifers— the Marine Connection

U.S. Geological Survey (USGS) | August 14th, 2002

Saltwater from the Pacific Ocean is seeping into some Los Angeles Basin coastal aquifers and replacing freshwater. Without treatment, this ground water does not conform t

Saltwater from the Pacific Ocean is seeping into some Los Angeles Basin coastal aquifers and replacing freshwater. Without treatment, this ground water does not conform to drinking-water or agricultural standards. This problem is significant because much of the water used by the nearly 10 million residents of Los Angeles County comes from ground-water sources. Although not all coastal aquifers in the region are at risk, the existing resources are vital and must be protected to maintain adequate supplies of potable water. In the 1950’s, construction began on the first of three “barriers” in an attempt to halt saltwater intrusion. Each barrier consists of a series of injection wells that essentially form a subsurface wall of freshwater designed to keep saltwater from penetrating further into aquifers. The barriers are only partly effective; saltwater continues to infiltrate in some areas. New studies show that the ground-water geohydrology of the coastal aquifers is more complex than previously imagined. U.S. Geological Survey (USGS) scientists, working in cooperation with the Water Replenishment District of Southern California and the Los Angeles County Department of Public Works, are expanding efforts to understand the geologic processes and fluid pathways that control saltwater intrusion.

Sampling for Per- and Polyfluoroalkyl Substances (PFAS) by the Groundwater Ambient Monitoring and Assessment Priority Basin Project

Publisher not available | May 25th, 2021

San Antonio Water Company v. Foothill Irrigation Company, et al

Superior Court of California, County of San Bernardino | July 25th, 1958

From "An Evaluation of California's Adjudicated Groundwater Basins" by Langridge et al: "The Cucamonga Basin is a small groundwater basin located in San Bernardino Co

From "An Evaluation of California's Adjudicated Groundwater Basins" by Langridge et al: "The Cucamonga Basin is a small groundwater basin located in San Bernardino County. In the 1950s, approximately 25 parties, mostly small local water companies and several individual water users, filed an action to adjudicate the rights to the basin’s groundwater and certain surface waters tributary to the basin. The subsequent adjudication resulted in a 1958 Decree that contains some provisions for the metering and recording of water production, inspection of records, prohibitions against new water production, and potential reductions in water production. The court did not appoint an official Watermaster for the basin, and annual reports are not required. Since adjudication, water use in the basin has shifted from primarily agricultural use to primarily municipal use. Today there are three main water agencies — Cucamonga Valley Water District, San Antonio Water Company, and West End Consolidated Water Company — that hold nearly all of the adjudicated rights in the basin and jointly manage the basin pursuant to the 1958 Decree. Studies differ regarding the condition of the basin. A 2007 Metropolitan Water District review indicates that water levels in key wells have decreased about 120 feet and that the basin is experiencing long-term decline. Basin managers point to production data that also shows water production in the basin can trend below the total allocated rights production data."

San Diego Basin Study

U.S. Bureau of Reclamation (USBR) | August 15th, 2017

The purpose of the San Diego Basin Study (Basin Study) is to determine potential climate change impacts on water supplies and demands within the San Diego region and to i

The purpose of the San Diego Basin Study (Basin Study) is to determine potential climate change impacts on water supplies and demands within the San Diego region and to identify how potential adaptation strategies could mitigate supply shortages. The intention of Task 2.3 is to create a computer simulation model to forecast supply and demand imbalances under current and future conditions, and current and future demands under a baseline water system infrastructure in the Study Area. This Interim Report describes the methodologies and findings of this Task. 

San Diego County Ecosystems: Ecological Impacts of Climate Change on a Biodiversity Hotspot

California Energy Commission (CEC) | August 27th, 2018

The diverse ecosystems, habitats, plants, and animals in the San Diego County region will be impacted by climatic shifts in multifold ways due to current and future vari

The diverse ecosystems, habitats, plants, and animals in the San Diego County region will be impacted by climatic shifts in multifold ways due to current and future variability, along with other factors including habitat loss and fragmentation, land use shifts, and changing fire regimes. While home to a major metropolitan area, San Diego County still hosts expanses of native and preserved habitats where management and conservation action could be greatly enhanced through science-based assessments and planning for climate change and increased climate variability. Projections of climate change in the region include warming by 4-9° F on average, and a 15-25% decrease in fall and spring precipitation with an increase in variability resulting in more frequent and intense droughts punctuated by increasingly rare yet extreme precipitation and flooding events. In addition, an increase in fire events and potential lessening of coastal marine influence may also affect San Diego’s ecosystems. Climate warming superimposed upon the pronounced spatially-varying temperature in the San Diego region will likely be associated with range shifts for many species resulting in novel community assemblages and biotic interactions and could create phenological mismatches. More frequent and intense heat waves may disproportionately affect younger age classes and reduce reproductive and survival rates of species sensitive to temperature extremes. With increasingly variable precipitation, drought may occur more frequently due to increased occurrence of dry days and could intensify because of warmer temperatures. Since drought disproportionately affects some species, these projected changes may cause structural changes to ecosystems. Santa Ana winds, occurring during increasingly dry fall months, would create ideal fire conditions. Coastal low clouds and fog along San Diego’s coast buffer this zone from the effects of warming and drying through shading and cooling. Although these marine stratus clouds will remain a presence, future changes in this phenomenon are uncertain. The spatial and temporal scales at which climate variations and change operate must be considered to build resilience into natural systems. Effective conservation actions will need to build on ongoing efforts focused on landscape-scale planning rather than more traditional single-species approaches. To carry this out will require cross-jurisdictional, multidisciplinary collaboration by scientists, policy-makers, planners, land managers, and the broader conservation community, which has a decades-long history of accomplishment in San Diego County.

San Fernando Groundwater Basin Remediation Program

Los Angeles Department of Water & Power (LADWP) | January 1st, 2018

San Gabriel Valley Groundwater Basin Salt And Nutrient Management Plan

Publisher not available | May 31st, 2016