Laserfiche WebLink
Santa Ana 2020 Urban Water Management Plan <br />arcadis.com <br />7-3 <br />The following sections provide a detailed discussion of the City’s water source reliability. Additionally, the <br />following sections compare the City’s projected supply and demand under various hydrological <br />conditions, to determine the City’s supply reliability for the 25-year planning horizon. <br />Factors Affecting Reliability <br />In order to prepare realistic water supply reliability assessments, various factors affecting reliability were <br />accounted for. These include climate change and environmental requirements, regulatory changes, water <br />quality impacts, and locally applicable criteria. <br />7.2.1 Climate Change and the Environment <br />Changing climate patterns are expected to shift precipitation patterns and affect water supply availability. <br />Unpredictable weather patterns will make water supply planning more challenging. Although climate <br />change impacts are associated with exact timing, magnitude, and regional impacts of these temperature <br />and precipitation changes, researchers have identified several areas of concern for California water <br />planners (MET, 2021). These areas include: <br /> A reduction in Sierra Nevada Mountain snowpack. <br /> Increased intensity and frequency of extreme weather events. <br /> Prolonged drought periods. <br /> Water quality issues associated with increase in wildfires. <br /> Changes in runoff pattern and amount. <br /> Rising sea levels resulting in: <br />o Impacts to coastal groundwater basins due to seawater intrusion. <br />o Increased risk of damage from storms, high-tide events, and the erosion of levees. <br />o Potential pumping cutbacks to the SWP and CVP. <br />Other important issues of concern due to global climate change include: <br /> Effects on local supplies such as groundwater. <br /> Changes in urban and agricultural demand levels and patterns. <br /> Increased evapotranspiration from higher temperatures. <br /> Impacts to human health from water-borne pathogens and water quality degradation. <br /> Declines in ecosystem health and function. <br /> Alterations to power generation and pumping regime. <br /> Increases in ocean algal blooms affected seawater desalination supplies. <br />The major impact in California is that without additional surface storage, the earlier and heavier runoff <br />(rather than snowpack retaining water in storage in the mountains), will result in more water being lost to <br />the oceans. A heavy emphasis on storage is needed in California. <br />In addition, the Colorado River Basin supplies have been inconsistent since about the year 2000, with <br />precipitation near normal while runoff has been less than average in two out of every three years. <br />Climate models are predicting a continuation of this pattern whereby hotter and drier weather conditions <br />will result in continuing lower runoff, pushing the system toward a drying trend that is often characterized <br />as long term drought.