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<br /> <br /> <br />List of Tilt-Up Buildings (Continued) <br /> <br />5.12.3 Flooding <br />Flood hazards in San Leandro are associated with overbank flooding of creeks and <br />drainage canals, dam failure, tsunamis, and rising sea level. <br />5.12.3.1 Overbank Flooding <br />At one time, flooding along creeks and streams was relatively common in San <br />Leandro. These hazards were greatly reduced during the 1960s and 1970s when the <br />Alameda County Flood Control and Water Conservation District (ACFCWCD) <br />channelized the lower portions of San Leandro Creek and constructed flood control <br />ditches in the southern part of the City. <br />Although the flood control channels were effective, they did not eliminate flood <br />hazards entirely. During the last 40 years, urbanization in the watersheds has <br />increased impervious surface area, which has resulted in faster rates of runoff and <br />higher volumes of stormwater in the channels. Recent maps published by the <br />Federal Emergency Management Agency (FEMA) indicate that a 100-year storm <br />(e.g., a storm that has a one percent chance of occurring in any given year) could <br />cause shallow flooding in parts of southwest San Leandro. <br />In 1999, the City appealed the flood zone boundaries established by FEMA, believing <br />that the number of flood prone properties had been overestimated. Revised maps <br />became effective in February 2000. Although the revised maps show fewer <br />properties in the flood zone than the 1999 maps did, the zones may still be <br />overstated. According to FEMA, there are still 1,870 homes in the Manor, Floresta <br />and Springlake neighborhoods within the 100-year floodplain. Flood insurance costs