Safety element S-3: Flood Hazards

Only areas below are considered part of the General Plan.

Flood Hazards

Floods are natural and recurrent events that generally do not pose a hazard when they occur in an undeveloped area; it is only when floods interact with the built environment— typically in the form of structures built in the floodplain, where they obstruct floodwaters— that they become hazardous. Unfortunately, as development in floodplains has increased, the average annual losses due to flooding have increased. Menifee is in the lower part of the San Jacinto River basin, a regional watershed of more than 700 square miles.  Most flooding in Menifee is the result of flows along the San Jacinto River, Salt Creek, and several smaller drainages along the City’s boundaries (including Ethanac Wash, the creek through Quail Valley, Paloma Wash, and Warm Springs Creek).  The City of Menifee is aware of these flood-prone areas and has plans to improve or replace some of the existing flood control structures to reduce the flood hazards.

Although new storm drain improvements have been constructed within and north of the City boundary, Line A Storm Drain Channel, portions of Romoland continue to be designated a Special Flood Hazard Area Zone (SFHA) and therefore subject to federal floodplain management regulations. SFHAs are areas subject to a high risk of inundation by a “base flood,” also referred to as the 100-year flood (a flood having a 1 percent chance of occurring annually). SFHAs are regulated zones, requiring the mandatory purchase of flood insurance. They are also subject to special standards and regulations that apply to new construction, and in some cases, existing buildings. In addition, currently there is one Critical Facility, Heritage High School, that is located in the 100-year flood zone; see Exhibit S-7– Critical Facilities. The City of Menifee encourages the efforts of the Homeland/Romoland Area Drainage Plan participants’ efforts  and has funded improvements for flood control facilities necessary to facilitate removing the area from the 100-year flood zone. Exhibit S-5; Flood Hazards, shows the Flood Insurance Rate Maps (FIRMs) inundation limits for the 100-year and 500-year flood; however, it should be noted that the study areas are limited and the flood zones are incomplete. Consequently, there are areas outside of the mapped flood zones that are likely to be subject to flood hazards.

Goal

• S-3: A community that is minimally disrupted by flooding and inundation hazards.

Policies

• S-3.1: Require that all new developments and redevelopments in areas susceptible to flooding (such as the 100-year floodplain and areas known to the City to flood during intense or prolonged rainfall events) incorporate mitigation measures designed to mitigate flood hazards.
• S-3.2: Reduce flood hazards in developed areas known to flood.
• S-3.3: Use technology to identify flood-prone areas and to notify residents and motorists of impending flood hazards and evacuation procedures.
• S-3.4: Develop floodplains as parks, nature trails, equestrian parks, golf courses, or other types of recreational facilities or joint-use facilities that can withstand periodic inundation wherever feasible.
• S-3.5: Encourage neighboring jurisdictions to require development occurring adjacent to the city to consider the impact of flooding and flood control measures on properties within Menifee.
• S-3.6: Coordinate with FEMA to ensure that flood mapping and flood risk information is current and available.
• S-3.7: When feasible locate new essential public facilities outside of flood risk areas, including, but not limited to, hospitals and health care facilities, emergency shelters, emergency command centers, and emergency communications facilities or identify other methods to minimize damage if these facilities are located in flood hazard zones.

General Plan Exhibits

• Exhibit S-1: Fault Map
• Exhibit S-2: Slope Distribution
• Exhibit S-3: Liquefaction and Landslides
• Exhibit S-4: Geologic Map
• Exhibit S-5: Flood Hazards
• Exhibit S-6: High Fire Hazard Areas
• Exhibit S-7: Critical Facilities
• Exhibit S-8: Very High Fire Hazard Severity Zones and Public Facilities
• Exhibit S-9: Evacuation Routes