San Francisco Bay and its watersheds are polluted by legacy polychlorinated biphenyls (PCBs), resulting in the establishment of a total maximum daily load (TDML) that requires a 90% PCB load reduction from municipal stormwater. Green infrastructure (GI) is a multibenefit solution for stormwater management, potentially addressing the TMDL objectives, but planning and implementing GI cost-effectively to achieve management goals remains a challenge and requires an integrated watershed approach. This study used the nondominated sorting genetic algorithm (NSGA-II) coupled with the Stormwater Management Model (SWMM) to find near-optimal combinations of GIs that maximize PCB load reduction and minimize total relative cost at a watershed scale. The selection and placement of three locally favored GI types (bioretention, infiltration trench, and permeable pavement) were analyzed based on their cost and effectiveness. The results show that between optimal solutions and nonoptimal solutions, the effectiveness in load reduction could vary as much as 30% and the difference in total relative cost could be well over $100 million. Sensitivity analysis of both GI costs and sizing criteria suggest that the assumptions made regarding these parameters greatly influenced the optimal solutions.
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This technical memo describes the purpose, functions, and structure associated with the newest addition to the GreenPlan-IT Toolset, the GreenPlan-IT Tracker. It also shares the opportunities for further enhancement and how the tool can operate in concert with existing resources. Furthermore, this memo describes a licensing plan that would permit municipalities to use the tool in an ongoing way that scales to their needs. The memo concludes with a provisional roadmap for the development of future features and technical details describing the tool’s platform and data structures.
Over the past 200 years, many of the channels that drain to San Francisco Bay have been modified for land reclamation and flood management. The local agencies that oversee these channels are seeking new management approaches that provide multiple benefits and promote landscape resilience. This includes channel redesign to improve natural sediment transport to downstream bayland habitats and beneficial re-use of dredged sediment for building and sustaining baylands as sea level continues to rise under a changing climate. Flood Control 2.0 is a regional project that was created to help develop innovative approaches for integrating habitat improvement and resilience into flood risk management at the Bay interface. Through a series of technical, economic, and regulatory analyses, the project addresses some of the major elements associated with multi-benefit channel design and management at the Bay interface and provides critical information that can be used by the management and restoration communities to develop long-term solutions that benefit people and wildlife.
This Flood Control 2.0 report provides a regional analysis of morphologic change and sediment dynamics in flood control channels at the Bay interface, and multi-benefit management concepts aimed at bringing habitat restoration into flood risk management. The findings presented here are built on a synthesis of historical and contemporary data that included input from Flood Control 2.0 project scientists, project partners, and science advisors. The results and recommendations, summarized below, will help operationalize many of the recommendations put forth in the Baylands Ecosystem Habitat Goals Science Update (Goals Project 2015) and support better alignment of management and restoration communities on multi-benefit bayland management approaches.
The Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) is a novel partnership between regulatory agencies and the regulated community to provide the scientific foundation to manage water quality in the largest Pacific estuary in the Americas. The RMP monitors water quality, sediment quality and bioaccumulation of priority pollutants in fish, bivalves and birds. To improve monitoring measurements or the interpretation of data, the RMP also regularly funds special studies. The success of the RMP stems from collaborative governance, clear objectives, and long-term institutional and monetary commitments. Over the past 22 years, high quality data and special studies from the RMP have guided dozens of important decisions about Bay water quality management. Moreover, the governing structure and the collaborative nature of the RMP have created an environment that allowed it to stay relevant as new issues emerged. With diverse participation, a foundation in scientific principles and a continual commitment to adaptation, the RMP is a model water quality monitoring program. This paper describes the characteristics of the RMP that have allowed it to grow and adapt over two decades and some of the ways in which it has influenced water quality management decisions for this important ecosystem.
Urban runoff has been identified in water quality policy documents for San Francisco Bay as a large and potentially controllable source of pollutants. In response, concentrations of suspended sediments and a range of trace organic pollutants were intensively measured in dry weather and storm flow runoff from a 100% urban watershed. Flow in this highly urban watershed responded very quickly to rainfall and varied widely resulting in rapid changes of turbidity, suspended sediments and pollutant concentrations. Concentrations of each organic pollutant class were within similar ranges reported in other studies of urban runoff, however comparison was limited for several of the pollutants given information scarcity. Consistently among PCBs, PBDEs, and PAHs, the more hydrophobic congeners were transported in larger proportions during storm flows relative to low flows. Loads for Water Years 2007-2010 were estimated using regression with turbidity during the monitored months and a flow weighted mean concentration for unmonitored dry season months. More than 91% of the loads for every pollutant measured were transported during storm events, along with 87% of the total discharge. While this dataset fills an important local data gap for highly urban watersheds of San Francisco Bay, the methods, the uniqueness of the analyte list, and the resulting interpretations have applicability for managing pollutant loads in urban watersheds in other parts of the world.
Contaminant concentrations from the Sacramento-San Joaquin River watershed were determined in water samples mainly during flood flows in an ongoing effort to describe contaminant loads entering San Francisco Bay, CA, USA. Calculated PCB and total mercury loads during the 6-year observation period ranged between 3.9 and 19 kg/yr and 61 and 410 kg/yr, respectively. Long-term average PCB loads were estimated at 7.7 kg/yr and total mercury loads were estimated at 200 kg/yr. Also monitored were PAHs, PBDEs (two years of data), and dioxins/furans (one year of data) with average loads of 392, 11, and 0.15/0.014 (OCDD/OCDF) kg/yr, respectively. Organochlorine pesticide loads were estimated at 9.9 kg/yr (DDT), 1.6 kg/yr (chlordane), and 2.2 kg/yr (dieldrin). Selenium loads were estimated at 16 300 kg/yr. With the exception of selenium, all average contaminant loads described in the present study were close to or below regulatory load allocations established for North San Francisco Bay.