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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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DOI: 10.1061/JSWBAY.0000876

Suspended sediment concentration (SSC) is of critical importance to the management of San Francisco Bay (SFB), yet has not been a focus of sustained high frequency monitoring efforts in shallow shoal and slough habitats that make up a majority of the area of the South Bay (SB) and Lower South Bay (LSB). In this report, we provide a status update for year one of a three year collaboration between the San Francisco Bay Nutrient Management Strategy (NMS) and Regional Monitoring Program (RMP) with the South Bay Salt Pond Restoration Project (SBSPRP) to estimate high frequency SSC throughout the SB and LSB. As a part of this effort, 15-minute turbidity data from seven locations, collected as part of the NMS Moored Sensor Program (MSP), was paired with monthly discrete SSC sampling, with the goal of creating a robust turbidity-SSC calibration. An additional turbidity-specific sensor was also deployed and paired with discrete SSC sampling on the shoal near the Eden Landing Whale’s Tail. Here we present preliminary results from turbidity-SSC calibrations at these eight sites, which together span a range of environments (deep channel, shoal, slough) representative of SFB. Following completion of this calibration, resource managers will be able to convert continuous high-frequency turbidity data to SSC at locations throughout SB and LSB, greatly aiding future sediment-focused efforts

This report provides a project update for year two of a three-year collaboration between the San Francisco Bay Nutrient Management Strategy (NMS), San Francisco Bay Regional Monitoring Program, and South Bay Salt Pond Restoration Project, to estimate high frequency suspended sediment concentration (SSC) in San Francisco Bay (SFB). Through its role in monitoring water quality in SFB, the NMS maintains an array of autonomous sondes that record high frequency (15-minute) water column turbidity, amongst a suite of other environmental parameters. Turbidity data from these monitoring sites was combined with discrete SSC samples to create a bay-wide turbidity-SSC calibration, allowing for estimates of high frequency SSC.