An assessment of future tidal marsh resilience in the San Francisco Estuary through modeling and quantifiable metrics of sustainability

Frontiers in Environmental Science (Frontiers) | November 25th, 2022

Quantitative, broadly applicable metrics of resilience are needed to effectively manage tidal marshes into the future. Here we quantified three metrics of temporal marsh

Quantitative, broadly applicable metrics of resilience are needed to effectively manage tidal marshes into the future. Here we quantified three metrics of temporal marsh resilience: time to marsh drowning, time to marsh tipping point, and the probability of a regime shift, defined as the conditional probability of a transition to an alternative super-optimal, suboptimal, or drowned state. We used organic matter content (loss on ignition, LOI) and peat age combined with the Coastal Wetland Equilibrium Model (CWEM) to track wetland development and resilience under different sea-level rise scenarios in the Sacramento-San Joaquin Delta (Delta) of California. A 100-year hindcast of the model showed excellent agreement (R2 = 0.96) between observed (2.86 mm/year) and predicted vertical accretion rates (2.98 mm/year) and correctly predicted a recovery in LOI (R2 = 0.76) after the California Gold Rush. Vertical accretion in the tidal freshwater marshes of the Delta is dominated by organic production. The large elevation range of the vegetation combined with high relative marsh elevation provides Delta marshes with resilience and elevation capital sufficiently great to tolerate centenary sea-level rise (CLSR) as high as 200 cm. The initial relative elevation of a marsh was a strong determinant of marsh survival time and tipping point. For a Delta marsh of average elevation, the tipping point at which vertical accretion no longer keeps up with the rate of sea-level rise is 50 years or more. Simulated, triennial additions of 6 mm of sediment via episodic atmospheric rivers increased the proportion of marshes surviving from 51% to 72% and decreased the proportion drowning from 49% to 28%. Our temporal metrics provide critical time frames for adaptively managing marshes, restoring marshes with the best chance of survival, and seizing opportunities for establishing migration corridors, which are all essential for safeguarding future habitats for sensitive species.

An Evaluation of Compensatory Mitigation Projects Permitted Under Clean Water Act Section 401 by the California State Water Resources Control Board, 1991-2002

California State Water Resources Control Board (SWRCB) | August 2nd, 2008

The purpose of this project, which was funded by the California State Water Resources Control Board (SWRCB), was to evaluate the compliance and wetland condition of compe

The purpose of this project, which was funded by the California State Water Resources Control Board (SWRCB), was to evaluate the compliance and wetland condition of compensatory wetland mitigation projects associated with Clean Water Act Section 401 Water Quality Certifications throughout California. This was done by selecting, reviewing and performing field evaluations for 143 permit files distributed across the 12 Water Board regions and sub-regions of the State. For each permit file we assessed the extent to which permittees complied with their mitigation conditions, including acreage requirements, whether the corresponding mitigation efforts resulted in optimal wetland condition, and if the habitat acreages gained through compensatory mitigation adequately replaced those lost through the permitted impacts. We found that permittees are largely following their permit conditions (although one-quarter to one-third of the time these are not met), but the resulting compensatory mitigation projects seldom result in wetlands with optimal condition.

An Introduction to EcoAtlas: Applied Aquatic Science

San Francisco Estuary Institute (SFEI) | September 14th, 2016

The term “EcoAtlas” has been in use for over 20 years in association with the study, assessment, and reporting of aquatic resources in California. What began as “W

The term “EcoAtlas” has been in use for over 20 years in association with the study, assessment, and reporting of aquatic resources in California. What began as “Wetland Tracker” in 2000, with its goal of recording essential information about wetland restoration projects in the greater Bay Area, later blossomed into a broad technological ecosystem of interrelated tools, each focused on delivering specialized, program-focused features, as defined by key stakeholder groups. Having evolved over time, EcoAtlas comprises a diverse toolset, but the collection shares common libraries, common approaches, and common development methodologies. Though each emerged from different funding opportunities and requirement drivers, the toolset collectively addresses a synthesized “whole watershed approach.” Whether estimating the ideal riparian buffer width for a given stream or assessing the health of a wetland at the edge of the estuary, the EcoAtlas tools allow practitioners to deploy the right tool for the job across the entire watershed, thereby producing a complete picture through composite outputs.

Analysis of the costs and benefits of using marsh restoration as a sea level rise adaptation strategy in San Francisco Bay

Bay Institute | February 22nd, 2013

The purpose of this study is to examine opportunities to protect San Francisco Bay’s recovering tidal marsh ecosystems while helping bayshore communities to manage the

The purpose of this study is to examine opportunities to protect San Francisco Bay’s recovering tidal marsh ecosystems while helping bayshore communities to manage the impacts of sea level rise. Specifically, it considers the flood risk management functions that tidal marshes perform naturally and evaluates the possibility of integrating those functions into a co-beneficial shoreline management strategy. The study’s intended audience is planners, politicians, regulators, and other stakeholders with the authority to make or affect decisions that influence the configuration and use of the San Francisco Bay shoreline. The study examines the current functions of San Francisco Bay tidal marshes as well as existing flood risk management strategies. It considers how environmental conditions are likely to change in the era of climate change, and how we can adapt our marshes and our flood risk management practices to accommodate these changes.

Annotated Bibliography for Sycamore Alluvial Woodland Habitat Mapping and Regeneration Studies Project

San Francisco Estuary Institute (SFEI) | February 27th, 2017

The California sycamore (Platanus racemosa) is a riparian tree native to California and northern Baja California. California sycamore is the dominant species in sycamore

The California sycamore (Platanus racemosa) is a riparian tree native to California and northern Baja California. California sycamore is the dominant species in sycamore alluvial woodland (SAW), a habitat type defined as open to moderately closed, winter-deciduous broad-leafed riparian woodland dominated by well-spaced Platanus racemosa (Holland 1986), and California sycamore also occurs in the “Platanus racemosa woodland alliance” with various associated species (Sawyer, Keeler-Wolf, and Evens 2009). The central California sycamore alluvial woodland (SAW) habitat type is cited in the Santa Clara Valley Habitat Plan (VHP) as a “very rare and threatened land cover type,” and the VHP contains various goals to conserve and restore SAW habitat. The San Francisco Estuary Institute (SFEI) and H. T. Harvey & Associates (HTH), in conjunction with the Santa Clara Habitat Agency, have undertaken the Sycamore Alluvial Woodland Habitat Mapping and Regeneration Studies Project to assess biotic and abiotic factors that influence California sycamore stand health and regeneration. The study is intended to gather and generate data that will be used by the Santa Clara Habitat Agency to guide acquisition and management of California sycamore habitat to meet its conservation goals. 

Applied Aquatic Science: A Business Plan for EcoAtlas

San Francisco Estuary Institute (SFEI) | March 7th, 2017

The EcoAtlas suite of tools represents a significant investment of time, energy, thought, scientific testing, technical innovation, and capital from a number of state and

The EcoAtlas suite of tools represents a significant investment of time, energy, thought, scientific testing, technical innovation, and capital from a number of state and federal public agencies, grant programs, and NGOs over the course of its 17-year existence. The toolset embodies the scientific and programmatic investments of the California Wetland Monitoring Workgroup (CWMW), its many related state and federal agencies, non-governmental organizations (NGOs), and private consultants, as well as the goals of the growing set of stakeholders who have expanded the circle of interested parties over the years. It is known by many names -- “WRAMP” being most common -- but in its essence it comprises the following tools:  ● EcoAtlas map viewer ● Project Tracker ● The California Aquatic Resources Inventory (CARI) map and editor tool ● The California Rapid Assessment Method (CRAM) ● The Riparian Zone Estimator Tool (RipZET) Now highly capable, the toolset represents more than science and technology alone, but a distillation of both, customized to meet specific goals associated with the landscape-scale tracking and characterization of California’s aquatic resources. The US Environmental Protection Agency (US EPA), for instance, has supported the toolset through multiple development grants so that the collected tools might be complementary to a still-nascent, statewide wetland protection program. Meanwhile, the state’s Coastal and Delta Conservancies require the use of the tool, and regional water boards -- including SF Bay, Lahontan, and North Coast -- regularly employ the tool for mitigation and restoration project tracking. Essentially, EcoAtlas has proven critical to a variety of programs and represents a successful product of broad-based collaboration. However, it currently stands at a crossroads, and its stakeholders must direct the toolset’s future. The following plan is intended to ensure the continued vitality of the toolset. The plan’s success will depend upon the continued collaboration of the public agencies that have supported the toolset thus far, but it must also integrate principles of resilience as it accounts for the tensions that arise as organizations move in different strategic directions. 

Averting disaster: Action now for the Salton Sea

Little Hoover Commission | September 1st, 2015

The Salton Sea is shrinking. Currently the state’s largest inland body of water, as it dries up, the Sea poses a substantial threat to public health and the environment

The Salton Sea is shrinking. Currently the state’s largest inland body of water, as it dries up, the Sea poses a substantial threat to public health and the environment. Left unaddressed, desert winds will lift dust from thousands of acres of newly-revealed lakebed and blow it into population centers, agricultural areas and world-class resort economies. This impending crisis is long in the making, a policy paralysis driven by years of government process without implementing a fix. There are clear, understandable and specific mitigation steps that should be taken immediately. The decisions California leaders make in the near future about this remote desert lake will determine whether this dismal scenario will be averted. The Commission urges the Natural Resources Agency to begin implementing shovel-ready projects and the Governor and Legislature to immediately begin planning and funding the next phase of Salton Sea projects while developing a long-term restoration plan. ... When California signed the QSA, it agreed to mitigate the impacts on the Salton Sea caused by the water transfers. The state clarified its intent to restore the sea through the QSA’s implementing legislation. Experts testified it would be tens of billions of dollars cheaper to mitigate the impacts of a shrinking sea up front than to deal with the adverse impacts of inaction. Fulfilling California’s commitment to the Salton Sea is an element of maintaining the terms of the QSA, which provides water security to many Californians. Continued inaction, and the consequent public health and environmental impacts, could undermine political support for the QSA. Further, in the larger picture, California’s fulfillment of its commitments is critical to its ability to negotiate future difficult agreements. ...    

Bathymetry and Digital Elevation Models of Coyote Creek and Alviso Slough, South San Francisco Bay, California

U.S. Geological Survey (USGS) | March 15th, 2018

In 2010 the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center completed three cruises to map the bathymetry of the main channel and shall

In 2010 the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center completed three cruises to map the bathymetry of the main channel and shallow intertidal mudflats in the southern most part of south San Francisco Bay. The three surveys were merged to generate comprehensive maps of Coyote Creek (from Calaveras Point east to the railroad bridge) and Alviso Slough (from the bay to the town of Alviso) to establish baseline bathymetry prior to the breaching of levees adjacent to Alviso and Guadalupe Sloughs as part of the South Bay Salt Pond Restoration Project. Since 2010 the USGS has conducted twelve additional surveys to monitor bathymetric change in this region as restoration progresses.

Bending the Curve of Global Freshwater Biodiversity Loss: An Emergency Recovery Plan

BioScience (Oxford University Press) | February 19th, 2020

Benefit Accounting of Nature-Based Solutions for Watersheds

Pacific Institute | March 1st, 2021

Nature-based solutions (NBS) have the potential to combat pressing global problems, including climate change, water security and biodiversity loss. This guide builds on

Nature-based solutions (NBS) have the potential to combat pressing global problems, including climate change, water security and biodiversity loss. This guide builds on Benefit Accounting of Nature-Based Solutions for Watersheds Landscape Assessment (Shiao et al., 2020), which highlights the barriers for businesses to implement NBS at a large scale. The primary challenge for corporations is that there is no standardized method to identify, estimate and monitor the benefits that NBS can provide, making it hard to build the case for investments in these solutions.