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City of San Leandro Alvarado Commerce Center Project <br /> 60 <br />i. Would the project expose people or structures to a significant risk of loss, injury, or death <br />involving flooding, including that occurring as a result of the failure of a levee or dam? <br />The project site is located in the inundation areas of two dams: Upper San Leandro Reservoir and <br />Lake Chabot. Lake Chabot is classified as a high hazard dam because its failure could result in a <br />significant loss of life and property damage. The California Division of Safety of Dams (DSOD) <br />inspects each dam on an annual basis to ensure the dam is safe, performing as intended, and is not <br />developing problems (San Leandro 2016a). <br />EBMUD owns and operates these two reservoirs, which store runoff from local watersheds for <br />water supply. Lake Chabot was built in 1892 and impounds approximately three billion gallons of <br />water that is used for non-potable water supply, emergency water supply, conservation/storage of <br />local runoff, and recreation (San Leandro 2016a). <br />Four miles upstream is the Upper San Leandro Reservoir, which was constructed in 1977 and holds <br />more than 13 billion gallons of water. This reservoir is closed to public access, except for the trail <br />system, and is used for raw water storage. While failure of these dams is extremely unlikely, most of <br />San Leandro would be flooded in the event of a dam failure of either Lake Chabot or Upper San <br />Leandro Reservoir (San Leandro 2016a). <br />Requirements for earthquake and flood safety for the EBMUD dams are imposed by the DSOD. <br />Chabot Dam is inspected monthly by EBMUD personnel along with annual inspections by DSOD <br />personnel. DSOD requires that embankments under its jurisdiction are safe enough to withstand a <br />maximum credible earthquake without an uncontrolled release of reservoir water. In 2003, DSOD <br />requested EBMUD to perform a stability evaluation of the Chabot Dam. The results, which were <br />issued in 2005, indicated that upgrading the dam and retrofitting the outlet works was warranted. <br />An Environmental Impact Report (EIR) was certified in December 2013 that discusses the proposed <br />seismic upgrade program in detail and the dam improvements are expected to begin in 2016. <br />However, EBMUD considers both Lake Chabot and Upper San Leandro dams to be stable and does <br />not expect them to breach (San Leandro 2016a). <br />The risk of dam failure is extremely low, with seismic strengthening soon to take place at Lake <br />Chabot, and continuing maintenance and further improvements taking place at both dams in the <br />future (Leandro 2016a). In addition, the project does not involve residential uses and would not <br />substantially increase the population of the area. Further, the project would not increase the <br />number of employees such that substantial indirect population growth in the area would occur <br />(Section 10, Population and Housing). <br />Due to the very low probability of a dam failure that results in inundation of San Leandro and that <br />no housing or population increases would occur from the project, this impact would be less than <br />significant. <br />LESS THAN SIGNIFICANT IMPACT <br />j. Would the project result in inundation by seiche, tsunami, or mudflow? <br />The nearest largest body of water to the project is the San Francisco Bay, which is over two miles to <br />the west of the project site. The project is also over two miles from Lake Chabot to the northeast. <br />Since the project site is not near any large bodies of water and is two miles inland from the San <br />Francisco Bay, the project site would not be subject to inundation by seiche, tsunami, or mudflow. <br />No impact would occur. <br />NO IMPACT <br />357