South Coast

Risks of ocean acidification in the California Current food web and fisheries: ecosystem model projections

Wiley | January 12th, 2017

The benefits and ecosystem services that humans derive from the oceans are threatened by numerous global change stressors, one of which is ocean acidification. Here, we d

The benefits and ecosystem services that humans derive from the oceans are threatened by numerous global change stressors, one of which is ocean acidification. Here, we describe the effects of ocean acidification on an upwelling system that already experiences inherently low pH conditions, the California Current. We used an end‐to‐end ecosystem model (Atlantis), forced by downscaled global climate models and informed by a meta‐analysis of the pH sensitivities of local taxa, to investigate the direct and indirect effects of future pH on biomass and fisheries revenues. Our model projects a 0.2‐unit drop in pH during the summer upwelling season from 2013 to 2063, which results in wide‐ranging magnitudes of effects across guilds and functional groups. The most dramatic direct effects of future pH may be expected on epibenthic invertebrates (crabs, shrimps, benthic grazers, benthic detritivores, bivalves), and strong indirect effects expected on some demersal fish, sharks, and epibenthic invertebrates (Dungeness crab) because they consume species known to be sensitive to changing pH. The model's pelagic community, including marine mammals and seabirds, was much less influenced by future pH. Some functional groups were less affected to changing pH in the model than might be expected from experimental studies in the empirical literature due to high population productivity (e.g., copepods, pteropods). Model results suggest strong effects of reduced pH on nearshore state‐managed invertebrate fisheries, but modest effects on the groundfish fishery because individual groundfish species exhibited diverse responses to changing pH. Our results provide a set of projections that generally support and build upon previous findings and set the stage for hypotheses to guide future modeling and experimental analysis on the effects of OA on marine ecosystems and fisheries.

River Floods Under Wetter Antecedent Conditions Deliver Coarser Sediment to the Coast

American Geophysical Union (AGU) | April 13th, 2025

Increasing hydrologic volatility—more extreme rain, and larger variations between wet and dry years—has become apparent in some regions, but few data exist to determi

Increasing hydrologic volatility—more extreme rain, and larger variations between wet and dry years—has become apparent in some regions, but few data exist to determine how intensifying hydrologic extremes affect sedimentary systems. Using uniquely high-resolution records of fluvial suspended sediment and coastal morphology, we quantify sedimentary responses from a steep, 357-km2 watershed in California under extreme wet and dry hydrologic conditions. In years with multiple 2- to 10-year floods, fluvial sediment coarsened significantly as the wet season progressed, with late-season floods delivering dominantly sand-sized material to the coast. Greater and coarser sediment supply under wetter antecedent conditions affected nearshore geomorphic evolution for 4–5 years. The watershed and coastal changes we documented point to an increasing role of sediment-related hazards (flooding and hillslope erosion) and resources (nearshore accretion) as wet seasons intensify.

Rivers of California

Pacific Gas & Electric Company (PG&E) | July 1st, 1962

Rules and Regulations of the Borrego Springs Watermaster

Superior Court of California, County of Orange | February 23rd, 2021

Safe Clean Water Water for Los Angeles County Residents

Los Angeles County Department of Public Works (LACDPW) | November 7th, 2017

We live in a water-scarce area, and forces outside of our control can threaten our local water resources, including lakes, rivers and beaches. LA Count

We live in a water-scarce area, and forces outside of our control can threaten our local water resources, including lakes, rivers and beaches. LA County residents rely heavily on imported water from the Sierra Mountains, the Central Valley and even from states as far away as Colorado. Climate change is causing more and more extreme weather conditions, making these remote sources more unreliable . The impacts of the recent five-year drought were widely felt here. Rainfall is an essential, local source of LA’s water . Rain runs through local rivers, creeks and streams and can be absorbed underground, replenishing groundwater, which is a local source of drinking water. However, because so much of our region is paved over, when we do experience heavy rain, too much of that precious water is lost to the ocean before we can capture it for use. Our local water resources are also threatened by toxins and pollution as stormwater runs through streets and over-paved areas into our rivers, creeks and streams. Pollution flows onto our beaches and into the ocean, posing a public health risk and harming marine life.

Salinity of deep groundwater in California: Water quantity, quality, and protection

National Academy of Sciences (NAS) | July 12th, 2016

Deep groundwater aquifers are poorly characterized but could yield important sources of water in California and elsewhere. Deep aquifers have been developed for oil and g

Deep groundwater aquifers are poorly characterized but could yield important sources of water in California and elsewhere. Deep aquifers have been developed for oil and gas extraction, and this activity has created both valuable data and risks to groundwater quality. Assessing groundwater quantity and quality requires baseline data and a monitoring framework for evaluating impacts. We analyze 938 chemical, geological, and depth data points from 360 oil/gas fields across eight counties in California and depth data from 34,392 oil and gas wells. By expanding previous groundwater volume estimates from depths of 305 m to 3,000 m in California’s Central Valley, an important agricultural region with growing groundwater demands, fresh [<3,000 ppm total dissolved solids (TDS)] groundwater volume is almost tripled to 2,700 km3, most of it found shallower than 1,000 m. The 3,000-m depth zone also provides 3,900 km3 of fresh and saline water, not previously estimated, that can be categorized as underground sources of drinking water (USDWs; <10,000 ppm TDS). Up to 19% and 35% of oil/gas activities have occurred directly in freshwater zones and USDWs, respectively, in the eight counties. Deeper activities, such as wastewater injection, may also pose a potential threat to groundwater, especially USDWs. Our findings indicate that California’s Central Valley alone has close to three times the volume of fresh groundwater and four times the volume of USDWs than previous estimates suggest. Therefore, efforts to monitor and protect deeper, saline groundwater resources are needed in California and beyond.

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.