FLOODPLAIN MANAGEMENT

Flooding in San Joaquin

Flooding is the most common natural disaster in the United States, affecting all 50 states. Flooding typically occurs when there is a failure of water control structure, such as a levee, or when water due to rain and/or snowmelt accumulates faster than it can be absorbed or carried away by a river. San Joaquin County faces flooding risk from both of these causes.

In the early 1900s, many natural wetlands in the San Joaquin Valley were drained for agricultural use. A system of levees was introduced to prevent water from flooding the natural wetlands, which are still monitored and maintained by reclamation districts today. These districts have elected officials who patrol the levees to ensure their safety and upkeep.

In the San Joaquin Valley, there are four major rivers (the Stanislaus River, Tuolumne River, Merced River, and Mokelumne River) as well as smaller tributaries, that flow into the San Joaquin River. Melting snowpack from the Sierra Nevada as well as rainwater is carried through these rivers until they drain into the San Joaquin Delta. In a normal year, reservoirs hold the water until it can be released in a controlled manner downstream, but high precipitation can fill the reservoirs. Even on clear days, solar radiation can melt the snowpack, potentially overwhelming the reservoirs.

The San Joaquin Delta, lined with levees. Image Courtesy of St. Mary's College of California.

Floodplain Management

Budget

San Joaquin County’s Floodplain Management Program, administered through the Department of Public Works, is:

  • A collaborative effort of a community program of corrective and preventive measures for reducing flood damage to properties
  • Intended to protect public health and safety; reduce flood damage to buildings and contents; prevent increases in flood damage from new construction; and to reduce the risk of erosion damage
  • To protect the natural and beneficial functions of the floodplain
  • Administered in accordance with the Federal Emergency Management Agency's policies
  • An opportunity for homeowners, renters, and business owners in our community to purchase federally-backed flood insurance through the National Flood Insurance Program
  • Through the County’s participation in the NFIP Community Rating System, residents of San Joaquin County’s unincorporated areas qualify for a flood insurance premium rate reductions
Levee Breach along the San Joaquin River. The breach resulted in the evacuation of 500 people in Manteca. Image courtesy of the San Joaquin County Office of Emergency Services

San Joaquin County is dedicated to reducing flooding risks and participates in the National Flood Insurance Program (NFIP) Community Rating System (CRS). This program rewards communities that take steps that go beyond minimum NFIP floodplain management requirements to reduce the risk from flooding. The County has a CRS classification of 7 which means that County residents with properties in areas with a high level of flood risk receive a 15% discount on their flood insurance premiums each year.

The County's Water Resources staff is available to perform site visits for existing structures, proposed new structures, and expansions of existing structures, to assist County residents in reducing their exposure to flood damage. Please call the Public Works Water Resources Division at (209) 468-9596 for additional information.

You are encouraged to learn about flood risks, flood zones and how to protect you and your property in the event of a flood. Below is more on this subject as well as additional resources:

Flood Zones

Find your FEMA flood zone and other locally determined flood hazard areas by calling the San Joaquin Department of Public Works Water Resources Division at (209) 468-3605 or by clicking on the following link: Interactive Flood Zone Map

FEMA’s Flood Insurance Rate Maps (FIRMs), which map SFHAs, are also available through FEMA’s website at https://msc.fema.gov/. Paper copies of FIRMs, along with other flood awareness publications, are available for review at:

  • Cesar Chavez Central Library, 605 North El Dorado Street, Stockton, California
  • San County Department of Public Works, 1810 East Hazelton Avenue, Stockton, California

It doesn’t end with the FEMA flood zones. Other critical habitat and areas of risk are featured in the following map resources:

FEMA Elevation Certificates are used to accurately rate flood insurance policies. Elevation Certificate information about structures built or substantially improved in SFHAs since 1992 are available to the public by contacting San Joaquin County Public Works Department at (209) 468-3089.

FLOODPLAIN MANAGEMENT

Budget

1810 E. Hazelton Avenue
Stockton, CA 95201
(209) 468-3000

CONTACT US

  • Department of Public Works - (209) 468-3000
  • Water Resources Division - (209) 468-3000
  • Stormwater Hotline - (209) 468-3055
  • Chris Boyer - Flood Management - (209) 468-9360
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