Floodplain Information — City Of Oxnard

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Floodplain Information Updates

The City of Oxnard has established this website to keep our residents updated on all FEMA activities that affect property in the City of Oxnard. Correspondences, flood maps, FEMA documents, and links to associated sites are provided within this webpage for your use. Please click here: FEMA Flood Maps, and follow the onscreen directions to determine if your property is in a floodplain.

Benefits of Natural Floodplains

Natural floodplains provide flood risk reduction benefits by slowing runoff and storing flood water. They also provide other benefits of considerable economic, social, and environmental value that are often overlooked when local land-use decisions are made.

Floodplains frequently contain wetlands and other important ecological areas which directly affect the quality of the local environment. Some of the benefits of floodplains to a functioning natural system include:

Fish and wildlife habitat protection
Natural flood and erosion control
Surface water quality maintenance
Groundwater recharge
Biological productivity
Higher quality recreational opportunities (fishing, bird watching, boating, )

See the Green Guide, published by the Association of State Floodplain Managers, for more information on the benefits of natural systems and the history of floodplain development.

Natural Floodplains and Flood Loss Reduction

Floodplains provide numerous flood loss reduction benefits as a result of their unique natural functions. Rivers and streams shape floodplain topography and influence riparian habitats and riverine ecosystems. Likewise, the physical characteristics of the floodplain shape water flows and can provide flood loss reduction benefits to include the following:

Excess water storage: Except in narrow, steep valleys and areas of coastal bluffs, floodplains allow floodwaters to spread out and temporarily store excess water. This reduces flood peaks and velocities and the potential for erosion. One acre of floodplain flooded 1 foot deep holds approximately 330,000 gallons of water. Flood storage is particularly important in urban areas where even small floods, for example from a 5-or10-year storm, can cause severe damage.

Flow rate and erosion reduction: In their natural vegetated state, floodplains slow the rate at which the incoming overland flow reaches the main water body in the area. Vegetation also reduces shoreline erosion. In coastal areas, floodplain features such as beaches, sand bars, dunes, and wetlands act as natural barriers to dissipate waves and protect back-lying areas from flooding and erosion.

Slowing runoff: A natural floodplain has surface conditions favoring local ponding and flood detention, plus subsurface conditions favoring infiltration and storage. Slowing runoff across the floodplain allows additional time for the runoff to infiltrate and recharge available groundwater aquifers when there is unused storage capacity. The slowing of runoff provides the additional benefit of natural purification of water as local runoff or overbank floodwater infiltrates and percolates through the floodplain alluvium (flat land area adjacent to a stream).

Flow regulation during non-flood periods: During non-flood periods, groundwater discharge acts to naturally regulate the flow in a river or the level of a lake or pond. In other words, during periods of abundant water, the water can enter the groundwater system whenever there is available capacity rather than contribute to seasonal flood peaks. During low flow periods, the water flows from the higher groundwater system into lower surface waters, so that the frequency and duration of extremely low flows is reduced.

Conserving Wildlife While Reducing Flood Risk

The nation’s coastal and riverine floodplains and surrounding land areas support large and diverse populations of plants and animals by providing habitat and critical sources of energy and nutrients for these organisms. Many species spend their entire lives in the habitats found in and adjacent to the floodplain. The wide variety of plants and animals supported directly or indirectly by floodplains constitutes an extremely valuable, renewable resource important for our economic welfare, aesthetic enjoyment, and physical well-being.

Community Rating System Program

The Community Rating System (CRS) is a voluntary incentive program that recognizes and encourages community floodplain management practices that exceed the minimum requirements of the National Flood Insurance Program (NFIP). Over 1,500 communities participate nationwide.

In CRS communities, flood insurance premium rates are discounted to reflect the reduced flood risk resulting from the community’s efforts that address the three goals of the program:

Reduce and avoid flood damage to insurable property
Strengthen and support the insurance aspects of the National Flood Insurance Program
Foster comprehensive floodplain management

Manage Floodplain Risk

Meeting National Flood Insurance Program (NFIP) requirements is the most cost effective way to reduce the flood risk to new buildings and infrastructure.

FEMA provides tools and resources to help communities navigate NFIP requirements and implement higher standards of floodplain management. State and federal agencies, tribal governments, local communities and property owners have a role in reducing flood risk and helping communities become more resilient.