East Bay Municipal Utility District (EBMUD), colloquially referred to as "East Bay Mud", is a public utility district which provides water and sewage treatment services for an area of approximately 331 square miles (860 km2) in the eastern side of the San Francisco Bay. As of 2018, EBMUD provides drinking water for approximately 1.4 million people in portions of Alameda County and Contra Costa County in California, including the cities of Richmond, El Cerrito, Hercules, San Pablo, Pinole, Lafayette, Moraga, Orinda, Danville, Oakland, Piedmont, Emeryville, Berkeley, Albany, Alameda, San Leandro, neighboring unincorporated regions, and portions of cities such as Hayward and San Ramon. Sewage treatment services are provided for 685,000 people in an 88-square-mile area (as of 2018). EBMUD currently has an average annual growth rate of 0.8% and is projected to serve 1.6 million people by 2030. Headquartered in Oakland, EBMUD owns and maintains 2 water storage reservoirs on the Mokelumne River, 5 terminal reservoirs, 91 miles (146 km) of water transmission aqueducts, 4,100 miles (6,600 km) of water mains, 6 water treatment plants (WTPs), 29 miles (47 km) of wastewater interceptor sewer lines and a regional wastewater treatment facility (WWTF) rated at a maximum treatment capacity of 320 MGD.

The Hayward Fault Zone is a right-lateral strike-slip geologic fault zone capable of generating destructive earthquakes. The fault was first named in the Lawson Report of the 1906 San Francisco Earthquake in recognition of its involvement in the earthquake of 1868. This fault is about 119 km (74 mi) long, situated mainly along the western base of the hills on the east side of San Francisco Bay. It runs through densely populated areas, including Richmond, El Cerrito, Berkeley, Oakland, San Leandro, Castro Valley, Hayward, Union City, Fremont, and San Jose.