San Joaquin Basin Flood‑MAR Watershed Studies Upper San Joaquin Watershed Study Area Report

California Department of Water Resources (DWR) | December 3rd, 2025

The San Joaquin Basin Flood‑MAR Watershed Studies (Watershed Studies) — comprising five watershed reports for Calaveras, Stanislaus, Tuolumne, Merced and Upper San Jo

The San Joaquin Basin Flood‑MAR Watershed Studies (Watershed Studies) — comprising five watershed reports for Calaveras, Stanislaus, Tuolumne, Merced and Upper San Joaquin watersheds and a Basinwide Summary — deliver data‑driven assessments of climate change vulnerabilities and adaptation that reveal risks and consequences and call for bold, coordinated solutions. In the San Joaquin Basin, the effects of climate change will exacerbate long-standing water management challenges. As these reports quantify, every water management sector — flood, water supply (surface and groundwater), and ecosystems — is vulnerable. Without bold action, the basin and its watersheds face mounting threats to communities, economies, and ecosystems. Although each watershed has unique characteristics, all confront a future climate that is hotter and characterized by more extreme weather. For flood management, the 2022 Central Valley Flood Protection Plan states clearly: Catastrophic flooding in the San Joaquin Basin is not a question of if, but when. Meanwhile, the reliability of water supplies is expected to worsen, and ecosystems face degradation. Click here to be taken to California Department of Water Resources Watershed Studies homepage

San Luis Rey Flood Control Project Whelan Mitigation Site Habitat Restoration Action

U.S. Army Corps of Engineers (USACE) | January 15th, 2014

The U.S. Army Corps of Engineers, Los Angeles District (Corps or Los Angeles District) and City of Oceanside (City) propose to restore southwestern willow flycatc

The U.S. Army Corps of Engineers, Los Angeles District (Corps or Los Angeles District) and City of Oceanside (City) propose to restore southwestern willow flycatcher (Empidonax traillii extimus, flycatcher) habitat along the San Luis Rey River, within the San Luis Rey River Flood Risk Management Project Area, to meet environmental commitments and permit requirements consistent with the Record of Decision signed by the South Pacific Division Commander, February 21, 2008, for the Final Integrated Post Authorization Decision Document/ Supplemental Environmental Impact Statement/Environmental Impact Report/Post Authorization Change Report for the San Luis Rey Flood Control Project from College Blvd. to the Pacific Ocean, San Diego, California (SLR PADD/FEIS/FEIR/PAC), July 2007. The proposed action would include active restoration of riparian habitat and floodplain. The proposed site, located along the San Luis Rey River within the existing flood risk management project site, is owned by the City of Oceanside, the project’s non-Federal sponsor, and is herein referred to as the Whelan Mitigation Site.

Scaling protection and restoration of natural infrastructure to reduce flood impacts and enhance resilience

Shore & Beach (American Shore and Beach Preservation Association) | October 1st, 2019

Restoring natural infrastructure offers much promise as a means to reduce both flood hazard and exposure to complement and supplement other flood damage reduction

Restoring natural infrastructure offers much promise as a means to reduce both flood hazard and exposure to complement and supplement other flood damage reduction strategies. Interest increased in flood risk reduction methods using natural and nature- based features, in part, because of increased recognition that such could provide both flood risk reduction and other benefits, such as water quality uplift, community recreational space, and fish and wildlife habitat. Recent flood disasters and the rising costs of disaster response and recovery have triggered policy shifts toward economi- cally efficient investments that enhance greater community resilience. While natural infrastructure is becoming more widely recognized as a tactic for building community and ecological resilience to erosion and flooding, it remains underutilized. Actions to aid consideration of natural infrastructure and scale up its use are presented.

Scaling protection and restoration of natural infrastructure to reduce flood impacts and enhance resilience

Shore & Beach (American Shore and Beach Preservation Association) | January 10th, 2020

Restoring natural infrastructure offers much promise as a means to reduce both flood hazard and exposure to complement and supplement other flood damage reduction strat

Restoring natural infrastructure offers much promise as a means to reduce both flood hazard and exposure to complement and supplement other flood damage reduction strategies. Interest increased in flood risk reduction methods using natural and nature-based features, in part, because of increased recognition that such could provide both flood risk reduction and other benefits, such as water quality uplift, community recreational space, and fish and wildlife habitat. Recent flood disasters and the rising costs of disaster response and recovery have triggered policy shifts toward economically efficient investments that enhance greater community resilience. While natural infrastructure is becoming more widely recognized as a tactic for building community and ecological resilience to erosion and flooding, it remains underutilized. Actions to aid consideration of natural infrastructure and scale up its use are presented.

Sea level rise and the drivers of daily water levels in the Sacramento-San Joaquin Delta

Nature Portfolio (Springer Nature) | December 17th, 2023

Sea Level Rise Impacts on Wastewater Treatment Systems Along the U.S. Coasts

American Geophysical Union (AGU) | April 13th, 2018

Wastewater treatment plants are susceptible to flooding resulting from sea level rise. Previous estimates of wastewater exposure have only considered the impacts of mar

Wastewater treatment plants are susceptible to flooding resulting from sea level rise. Previous estimates of wastewater exposure have only considered the impacts of marine flooding at the local or regional scale. In this analysis, we quantify the exposure to marine flooding across the coastal United States and then consider the relative impacts of marine and groundwater flooding at the regional scale in the San Francisco Bay Area. We also estimate the number of people who may lose access to wastewater services if no actions are taken to prevent flooding at wastewater treatment plants. We find that the number of people impacted by sea level rise due to loss of wastewater services could be five times as high as previous predictions of the number of people who experience direct flooding of their homes or property. We also find that groundwater flooding poses a significant threat to wastewater plants in the San Francisco Bay region.

Sea Level Rise in California

Public Policy Institute of California (PPIC) | February 29th, 2024

Sea Level Rise Vulnerability Study for the City of Los Angeles

University of Southern California Sea Grant Program | December 31st, 2013

Climate change is expected to usher in an era of higher temperatures, increased precipitation and/or severe drought, and increased rates of sea level rise around

Climate change is expected to usher in an era of higher temperatures, increased precipitation and/or severe drought, and increased rates of sea level rise around the world. According to the National Research Council (NRC), global sea level has risen at an increasing rate since the late 19th / early 20th Century, when global temperatures first started to rise. Climate researchers believe sea level rise will drive storm surge and wave run-up higher than current conditions, thereby causing more extensive and frequent coastal, storm-driven flooding. Sea level rise in Los Angeles is expected to match global projections over the next century with anincrease of 0.1 - 0.6 meters (m), or 0.3 - 2.0 feet (ft), from 2000 - 2050 and 0.4 - 1.7 m (or 1.3 - 5.6 ft) from 2000 - 2100 (NRC 2012). Tides, wave-driven run-up, and storm surge play critical roles in coastal flooding in Southern California, especially when big wave storms occur at or near peak high tides. Sea level rise will potentially exacerbate the damage from these events.

Sea-Level Rise for the Coasts of California, Oregon, and Washington: Past, Present, and Future

National Academy of Sciences (NAS) | December 13th, 2012

Seasonality of Retreat Rate of a Wave-Exposed Marsh Edge

American Geophysical Union (AGU) | July 10th, 2024

Waves can cause destruction of marshlands when they collide with the boundary of the marsh area. We studied how the speed of marsh loss from waves can change between seas

Waves can cause destruction of marshlands when they collide with the boundary of the marsh area. We studied how the speed of marsh loss from waves can change between seasons with different climates. To do this we made five 3D models of a marsh in South San Francisco Bay over a single year and looked at their differences between summer/fall/winter/spring. We found fast marsh loss in the seasons where daily winds are common (spring/summer), and minor changes in seasons with storms but without daily winds (fall/winter). Across our entire marsh, we saw lots of variety in how much it was changing, including some addition (i.e., positive change) to the mudflats near the marsh in the fall/winter. When we compared the marsh loss over one year to what was lost between 2004 and 2019, the speeds were similar, so we believe our study period was similar to long‐term marsh dynamics. This work encourages incorporating different seasonal climates into expectations of how marshes evolve, and supports that we need to think about marshes and mudflats as connected in how they change over time.