City of Irvine
2020 Local Hazard Mitigation Plan
Risk of Future Events
Due to the presence of several dams in and near Irvine, many residents and businesses could be at risk of inundation in the case of significant dam failure. All dams identified in Exhibit 3-1 are considered to have an “Extremely High Downstream Hazard classification due to the prox imity to homes and businesses. Some of the potential consequences of dam failure from these facilities are death or injury, displacement of people from their homes, damage to existing public and private buildings, damage to infrastructure, loss of services from utilities, loss of government services, and economic losses. The DSOD requires periodic evaluation of dams based on confirmed or unconfirmed safety issues, probability of failure, and the potential consequences. All dams that may impact Irvine currently meet satisfactory conditions regarding dam safety.
Climate Change Considerations
Climate change could increase the risk of dam failure in the future. More intense rainstorms may increase the likelihood that reservoir infrastructure could become overwhelmed, including the dams that control floodwaters from inundating Irvine and the rest of Orange County. Indirectly, increased climate change- induced rains may cause more erosion, which could compromise the structural integrity of the dam or the foundation it sits on. For these reasons, monitoring of changing precipitation regimes and conditions is recommended to ensure future conditions are better understood.
Diseases and Pests
This section discusses agricultural pests, epidemic/ vector-borne diseases, and tree mortality hazards in the City of Irvine.
Description
A disease is a serious type of illness that affects an organism (trees, the human body, etc.) to the degree that normal activities can become more hampered, difficult, or even impaired. In serious cases, diseases can result in significant damage or even death. For humans, some diseases only affect the person who is infected — in this case, the disease would be considered non-contagious. For example, a person can be infected with Lyme Disease by interacting with an animal infected with ticks, but the infected person cannot then spread Lyme Disease to another person. Diseases that are spread from one person to the next are described as being contagious. While both types of disease are a hazard of concern for Irvine, contagious diseases are particularly concerning since they can result in multiple cases of the same disease if proper precautions are not enabled. Pests are organisms whose presence is generally considered a nuisance due to the public health and property damage they can cause. Examples of pests include mice, rats, mosquitoes, and invasive insects that cause damage to natural assets (trees). These organisms can be vectors, or transmitters, of disease which are spread by pests to animals and humans. Occasionally, the disease may spread first to an intermediary, like a domesticated animal, where it may evolve into a form that can survive in humans. These kinds of vector-borne diseases are known as zoonoses. Apart from posing risks to public health, pests can also damage property, such as trees or other landscaped areas, either by directly consuming the plant material or spreading infectious diseases. In serious cases, pests can cause the death of the tree or plant specimen they are infesting.
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