Reso 2025-151 Environmental Hazards Element General Plan

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S A N L E A N D R O G E N E R A L P L A N E N V I R O N M E N T A L H A Z A R D S 7-7 Landslides and Erosion Landslides are relatively common in the East Bay Hills, especially during high intensity rainstorms. Most slides occur naturally, but they may be exacerbated by excessive grading, improper construction, and poor drainage. The San Leandro Hills have a history of destructive landslides, including a 1998 event that required the relocation of two homes and threatened five others. Any additional development in the hills must be carefully engineered to avoid the risk of further property damage or loss of life. Projected increases in the intensity of atmospheric river events and extreme precipitation associated with climate change may also exacerbate existing landslide risks in the San Leandro Hills. Erosion is the wearing away of the soil mantle by running water, wind, or geologic forces. It is a naturally occurring phenomenon and ordinarily is not hazardous. However, excessive erosion can contribute to landslides, siltation of streams, undermining of foundations, and ultimately the loss of structures. Removal of vegetation tends to heighten erosion hazards. The City enforces grading and erosion control ordinances to reduce these hazards. Maintenance programs along San Leandro Creek also reduce the threat of erosion. Wildfire The risk of urban wildfire in California has increased dramatically as a result of population growth on fire-prone hillsides and the effects of drought and climate change. The danger is not just limited to rural areas. In 1991, an urban wildfire took place just eight miles north of San Leandro causing 25 deaths and $3 billion in property damage and resulted in the loss of over 3,000 homes in the Oakland Hills. Resolution No. 2025-151 Exhibit A 7 of 84