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of each gage installations and any post-processing applied to the data, and shall aiso include a section presenting the collected data, including maps and time-series plots.The post-processed survey and gage data will also be made available to city staff. Task 2 Pertorm Simulations of Existing Conditions The consultant shail develop a two-dimension (2D) hydraulic model to simulate water circulation and mixing within the Redwood Shores Lagoon. The model shall represent the key processes controlling mixing and exchange between the Lagoon and the neighboring San Francisco Bay channels and also internal exchange between different sub-regions of the Lagoon. The use of a 2D model will allow the Consultant to resolve spatial variations in mixing and exchange within the Lagoon. Even if the Lagoon as a whole experiences the desired volumetric exchange rate, sub-regions may experience insufficient circulation leading to poor water quality and undesirabie sedimentation and plant growth. The hydraulic model will predict water quality indicators such as the hydraulic residence time and volumetric exchange rate, and shall be setup to accommodate potential modifications to existing lagoon conditions. Subtask 2-1 Model Setup, Calibration,and Validation The 2D model shall be configured to resolve circulation and mixing at the scale of the narrowest channels, such that it can provide insight into the physical causes which lead to insufficient mixing at any particular location. The model shall simulate the key physical processes which drive mixing and exchange, including gravity- driven inflows and circulation, pump operations and the hydraulic function of existing channels, culverts, and tide gates. The modeling effort shall include sensitivity analysis to evaluate the importance of additional processes such as wind-driven mixing and evaporation, and shall include these additional processes as needed to accurately represent conditions at the lagoon. The hydraulic model shall be calibrated to match the observed water levels and salinity data collected under Task 1-3. Ideally, this new data from Task 1-3 will cover a range of water levels and salinities. Salinity can serve as a passive tracer which drops in response to precipitation and runoff and then recovers as Bay water replaces the freshwater. So calibrating to salinity changes will provide greater confidence that the model is not only exchanging the right amount of water (which could be determined from water levels alone), but that the model is also characterizing the mixing within the Lagoon. Subtask 2-2 Virtual Tracer Assessment Once the model is calibrated and validated, it can be used to better understand the existing patterns of hydraulic exchange and mixing both for the local problem spots and for the lagoon at large. Simulated passive tracer releases shall be used to map the predicted hydraulic residence times and exchange rates across the Lagoon's sub-regions. This tracer analysis will be processed to produce maps depicting the spatial variation of hydraulic residence times and across the entire lagoon. These variations in water quality parameters shall be correlated with the physical parameters which drive mixing and exchange, including 2D representations of w�ter levels, currents, and bed shear stresses within the lagoon. Consultant shall provide an engineering memorandum describing the model set-up and calibration for existing conditions. This memorandum shall include a description of the data sources used in the development of the hydraulic model and shall describe model calibration and validation based on REV:04-09-14 VR Page 11 of 16 ATTY/AG R.2014.048/E SA_88464