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Public Review Draft <br />Page 36 San Leandro 2021 Climate Action Plan <br />Drought <br />A drought occurs when conditions are drier than normal for an extended period, making less water <br />available for people and ecosystems. Droughts are a regular occurrence in California; however, <br />scientists expect that climate change will lead to more frequent and more intense droughts <br />statewide. Overall, precipitation levels are expected to remain similar, with more years of extreme <br />precipitation events. East Bay Municipal Utility District (EBMUD) obtains fresh water supplies for <br />San Leandro and other East Bay communities from the Mokelumne River watershed in the Sierra <br />Nevada. <br />Drought conditions can cause smaller streams to run dry, which can subsequently harm the plants <br />and animal habitats within the ecosystem. In an early-century drought (2023 to 2042), the City could <br />experience a drop in average precipitation from an average of 19.0 inches per year to an average <br />of 16.7 inches per year, which would lower baseflows in streams from an average of 4.9 inches per <br />day to 3.7 inches per day.34 In a late-century drought (2051 to 2070), precipitation could also drop <br />to an average of 16.7 inches per year and cause baseflows in streams to drop to 3.6 inches per <br />day.35 Drought conditions could lower water quality and raise water temperatures, reducing <br />dissolved oxygen levels and promoting algae growth that can harm a variety of fish species.36 <br />Wetlands and riparian habitats could experience increased soil erosion, degradation of landscape <br />quality, and loss of biological productivity. Since wetlands act as a buffer between developed areas <br />and San Francisco Bay, helping to protect the community from SLR and bayshore flooding, <br />degradation of wetlands could reduce the amount of water that the ecosystem can absorb and limit <br />the protection that the wetlands provide. Drought conditions can also dry out vegetation, increasing <br />its vulnerability to pests and disease and promoting wildfire conditions. <br />Extreme Heat <br />Extreme heat occurs when temperatures rise significantly above normal levels. In San Leandro, an <br />extreme heat day occurs when temperatures reach above 88.8 degrees Fahrenheit (°F). As shown <br />in Figure 9, the number of extreme heat days in San Leandro is projected to increase from 4 days <br />historically, to an average of 12 extreme heat days per year by midcentury and an average of up to <br />22 extreme heat days per year by the end of the century. <br />Extreme heat can also occur in the form of warmer nights when temperatures do not drop overnight <br />and provide relief from the heat. In San Leandro, a warm night occurs when the temperature <br />remains above 60.9°F.1 As shown in Figure 10, the number of warm nights in San Leandro is <br />projected to increase from an average of 4 historically, to an average of 50 warm nights per year <br />by midcentury, and an average of up to 120 warm nights per year by the end of the century. <br /> <br /> <br />1 According to Cal-Adapt, a warm night occurs when daily minimum temperature is higher than 98 percent of the <br />observed daily minimum temperatures between April and October from 1961 to 1990. <br />80