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File Number: 20-124 The National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973 led to the creation of flood insurance rate maps (‘flood maps’ or FIRM) which classify the risk of flooding for each parcel of land. The flood maps have been updated many times since 1973 and the most recent update, in December 2018, indicates that when there is both high tide and high storm water runoff at the same time, there is a 1% risk of flooding for portions of the Marina Faire and Mulford Gardens neighborhoods. The District has designed modifications to the canal to prevent water from overtopping the north bank of the canal and reducing the risk of flooding for these neighborhoods by storing storm water during high flow and high tide conditions in the City’s dredge materials management site (DMMS) immediately adjacent and south of the canal. Additionally the District plans to reconstruct the exiting deteriorating tide gate structure approximately 465 feet east of Monarch Bay Drive Bridge. In 1977 the City built the Neptune Drive Bridge over the Estudillo Canal, the name of the road and bridge were later changed to the Monarch Bay Drive. The bridge carries the Bay Trail for bicycles and pedestrians and is used by service vehicles to maintain the trail, the marshland south of the Estudillo Canal, and a treated effluent pumping station. The bridge also serves as a secondary exit for the Heron Bay neighborhood should the primary neighborhood exit to Lewelling Boulevard be blocked for a significant amount of time. The southern abutment of the Monarch Bay Drive Bridge has experienced erosion due to storm surges and daily tidal flows and is in need of maintenance work. The northern abutment received maintenance work in 2014 and is in good condition. The work on the Estudillo Canal and the Monarch Bay Drive bridge are of similar character, requires permits from the same agencies, and contractors that are interested in one project are likely interested in both. These characteristics highlighted the opportunity for efficiency by completing the projects together. As such, the District prepared and submitted environmental regulatory permit applications for the combined project and has secured the necessary permits prior to beginning of construction. Analysis To improve the flood control capabilities of the Estudillo Canal west of Wicks Boulevard, the District, after completing a hydraulic study, requested permission to occasionally divert storm water in to the City’s DMMS during major storm events. The temporarily diverted storm water flow would then drain back into the Estudillo Canal within approximately 48 hours. Granting this permission will require that the City maintain the DMMS in a condition suitable for accepting the storm water and will allow the District to construct improvements, which will reduce the risk of flooding from the Estudillo Canal for approximately 1,100 parcels of land within San Leandro. It is uncertain whether or not the canal could be designed to prevent overtopping and not use the DMMS for temporary storage, but it is certain that if it is possible to prevent overtopping the project would be considerably more expensive. The District will need an easement to allow maintenance for a portion of the proposed improvements that encroach upon the City owned DMMS. This easement will be completed within six (6) months of executing the proposed Agreement. Page 2 City of San Leandro Printed on 4/15/2020 90