Trees, Hydrology, Urban-Greening, and Nature-Based Solutions

Two key reports support nature-based solutions. Green stormwater infrastructure (GSI) and enhancements to the urban tree canopy offer benefits to stormwater management, urban ecological improvements, and complementary urban greening activities.

On KGO TV, these projects were featured on July 1, 2021.

Trees and Hydrology in Urban Landscapes

Effective implementation of urban greening strategies is needed to address legacies of landscape change and environmental degradation, ongoing development pressures, and the urgency of the climate crisis. With limited space and resources, these challenges will not be met through single-issue or individual-sector management and planning. Increasingly, local governments, regulatory agencies, and other urban planning organizations in the San Francisco Bay Area are expanding upon the holistic, portfolio-based, and multi-benefit approaches.

Next Generation Urban Greening

SFEI is working with partners across the Bay Area to design tools to help cities achieve biodiversity, stormwater, and climate benefits through multifunctional green infrastructure.

Toxic Tire Contaminant Found in Bay Area Stormwater

Scientists at the San Francisco Estuary Institute (SFEI) have found a highly toxic tire-related contaminant at levels lethal to coho salmon in stormwater flowing through four sites in the Bay Area. The contaminant, derived from a tire preservative, has been discovered by Washington state researchers to be responsible for high levels of coho salmon deaths in Puget Sound streams. These findings will  inform a petition by state stormwater leaders to the Department of Toxic Substances Control to address pollution of California streams caused by tires.

The research team, led by scientists at the University of Washington and Washington State University, published the results of their investigation yesterday in the journal Science. The chemical, 6PPD-quinone (pronounced "kwih-known"), can wash into streams along with tire wear particles when it rains. Scientists at San Francisco Estuary Institute collected samples from nine Bay Area streams and storm drains during storm events; four contained levels of this contaminant above the concentration at which half the coho salmon die after a few hours of exposure in laboratory experiments. SFEI’s Alicia Gilbreath and Rebecca Sutton are co-authors on the study.

Big problem, small size: Improving methods in microplastics research

When it comes to plastic pollution, that candy wrapper half buried in the dirt is only the tip of the iceberg. Plastic bags, cigarette butts, and bottle caps are not just an eyesore, but over time they break down in the environment, creating small pieces of debris known as microplastics. Microplastics can include anything from synthetic fibers of clothing to industrial pellets from the plastic manufacturing process. Microplastics are now ubiquitous in our environment--found in our air, drinking water, sediment, and in the San Francisco Bay and global ocean.     

Methods Matter: Methods for Sampling Microplastic and Other Anthropogenic Particles and Their Implications for Monitoring and Ecological Risk Assessment

Hung, C.; Klasios, N.; Zhu, X.; Sedlak, M.; Sutton, R. 2020. Methods Matter: Methods for Sampling Microplastic and Other Anthropogenic Particles and Their Implications for Monitoring and Ecological Risk Assessment. Integrated Environmental Assessment and Management 16 (6) . SFEI Contribution No. 1014.

To inform mitigation strategies and understand how microplastics affect wildlife, research is focused on understanding the sources, pathways, and occurrence of microplastics in the environment and in wildlife. Microplastics research entails counting and characterizing microplastics in nature, which is a labor‐intensive process, particularly given the range of particle sizes and morphologies present within this diverse class of contaminants. Thus, it is crucial to determine appropriate sampling methods that best capture the types and quantities of microplastics relevant to inform the questions and objectives at hand. It is also critical to follow protocols with strict quality assurance and quality control (QA/QC) measures so that results reflect accurate estimates of microplastic contamination. Here, we assess different sampling procedures and QA/QC strategies to inform best practices for future environmental monitoring and assessments of exposure. We compare microplastic abundance and characteristics in surface‐water samples collected using different methods (i.e., manta and bulk water) at the same sites, as well as duplicate samples for each method taken at the same site and approximate time. Samples were collected from 9 sampling sites within San Francisco Bay, California, USA, using 3 different sampling methods: 1) manta trawl (manta), 2) 1‐L grab (grab), and 3) 10‐L bulk water filtered in situ (pump). Bulk water sampling methods (both grab and pump) captured more microplastics within the smaller size range (<335 μm), most of which were fibers. Manta samples captured a greater diversity of morphologies but underestimated smaller‐sized particles. Inspection of pump samples revealed high numbers of particles from procedural contamination, stressing the need for robust QA/QC, including sampling and analyzing laboratory blanks, field blanks, and duplicates. Choosing the appropriate sampling method, combined with rigorous, standardized QA/QC practices, is essential for the future of microplastics research in marine and freshwater ecosystems.

Demonstration of a Watershed Approach to Wetland Restoration Planning for Load Reductions: A Pilot Demonstration Project Using GreenPlan-IT in the Santa Rosa Plain, Sonoma County, California

Wu, J.; Kauhanen, P.; Lowe, S.; Pearce, S.; Josh Collins. 2017. Demonstration of a Watershed Approach to Wetland Restoration Planning for Load Reductions: A Pilot Demonstration Project Using GreenPlan-IT in the Santa Rosa Plain, Sonoma County, California. SFEI Contribution No. 996. San Francisco Estuary Institute: Richmond. CA.

This summary memorandum presents technical recommendations to the 401 Certification and Waste Discharge Program (401 Program) of the State Water Resources Control Board (State Board) for a coherent, scientifically sound, repeatable, watershed approach to wetland restoration site evaluation, compliance monitoring and assessment, and Tracking. The recommendations are drawn from the previous four memoranda produced for the Pilot Demonstration Project (Project) that address the following subjects: project work plan and information flow diagram; scientific literature review; landscape scenario planning (to map and prioritize restoration opportunities); and a framework for a watershed-approach to evaluate and report the capacity of a wetland restoration site to protect wetland beneficial uses.

This Project focused on a sub-watershed of the Santa Rosa Plain, in Sonoma County, California. The area was chosen for the Project for three reasons: (1) it is integral to an existing nutrient TMDL and therefore is supported relatively well with hydrological and nutrient data; (2) the historical and existing wetlands and streams of the area were mapped recently in sufficient detail to inform landscape planning; and (3) implementation of the TMDL will involve wetland restoration to reduce downstream nutrient loads, and therefore the Project may help implement the TMDL.

The primary overall purpose of this Project was to explore how numerical simulation and statistical modeling could be combined with existing wetland assessment and reporting tools to create a coherent, watershed-based approach to wetland beneficial use protection. Any relevance to the existing nutrient TMDL for the demonstration area is an intentional, but secondary benefit of this Project.

PFAS Stays in San Francisco Bay

SFEI senior scientist, Dr. Rebecca Sutton, published a new study in the journal Chemosphere showing that it will take almost 50 years for PFOA concentrations in water to stabilize in San Francisco Bay. This pales in comparison to the trajectory of PFOS concentrations that will not stabilize in sediment and fish for 500 years. PFOS and PFOA are harmful to humans, causing liver damage, endocrine disruption, fertility decrease, and cancer.

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