The choice is simple for 22,000 property owners in parts of Manteca, Lathrop, and Stockton that have received ballots in the mail from the San Joaquin Area Flood Control Agency.
They can:
*vote yes and have annual assessments that, depending upon where their home is located in the 200-year floodplains, could run between $10.52 and $83.44 a year based on an 1,800-square-foot home, to make a $472 million flood protection project possible.
*vote no to effectively spike the project and — if they have a federally guaranteed mortgage — face the likelihood they will be required to obtain FEMA flood insurance at an annual cost averaging around $1,700 annually on top of existing home insurance premiums.
The flood insurance will not cover all damages incurred during a flood. At the same time, FEMA payments are notoriously slow.
The deadline for returning ballots is June 20.
The assessments will allow SJAFCA to leverage 67.7 percent of the cost of the $472 million project from federal and state sources.
That leaves a local share of $110.3 million.
Given the cost of the overall project that includes raising levees, developing seepage berms, cutoff walls, erosion protection and the extension of the dryland levee to the south of Manteca, the project cannot move forward without federal and state help.
If the assessments are not approved, it will effectively stop all building — new development to even adding on a room or a garage — in the area in the floodplain unless what is built is elevated out of the flood zone which adds significantly to building costs.
The state mandate for 200-year flood protection after it was determined by FEMA that the area around the San Joaquin-Sacramento Delta had the highest risk in the United States for a repeat of the 2005 Hurricane Katrina disaster in New Orleans.
The area covered by the levee work was expanded to include parts of Manteca east of Airport Way after a new California Department of Water Resources modeled showed there likely will be at least a tripling of flows in the San Joaquin River due to changing weather patterns.
The three times plus increase in river flows by 2070 would mean an additional five feet of water flowing by levees at the French Camp Slough.
Flooding losses on an annualized basis — meaning the cost of catastrophes that occur spread over a number of years — is placed at $47 million and would more than likely include a loss of life.
The DWR modeling plus pending changes in how FEMA identifies flood zones, meant an additional zone — that includes areas east of Airport Way in Manteca including parts of Del Webb, areas around Chaswick Square and farther south — was created.
The assessments in that area will be lower than elsewhere, averaging $10.52 a year.
That’s because the flood threat is the lowest.
Various models show precipitation patterns are slowly changing over Northern and Central California as they have done in a repeated cyclical pattern over the course of thousands of years.
As a result, flooding frequency is expected to rise.
Models point to less snow in the Sierra and more rain in the foothills and on the valley floor.
That means precipitation shifts could reduce the effectiveness of the flood control functions of major reservoirs. It may be due to more frequent warm rain melting snowpack throughout the winter, more perception falling below the basins feeding into reservoirs, or a combination of both.
As such, that increases the odds for flooding in Manteca — as well as Lathrop — given both cities are along the “last miles” where the 15,600 square miles of the San Joaquin River basin drains into the Delta.
Manteca — along with Lathrop, Stockton, and San Joaquin County — have been working to address the issue long before climate change entered the everyday vernacular.
It started with the California Legislature requiring more robust levees to protect against 200-year flood zones after levee failed in New Orleans during Hurricane Katrina.
Local concerns, though, preceding that as the paving over of land with impervious surfaces — streets, parking lots, rooftops, sidewalks and such upstream — had been increasing runoffs and the frequency of flooding measured by 100 year events.
In flood lingo, a 200-year event doesn’t mean a flood that will happen every 200 years.
Instead, it reflects the odds of such an event happening in any given year. That means there is a 1 in 200 chance of an event occurring in any given year requiring the levee work now being pursued.
Roughly 40 areas in California including Manteca-Lathrop-Stockton fall within peer reviewed science that designated 200-year flood plains. They must have — or be in the physical process of constructing — protection to guard against such an event by 2030.
If such areas fail to do so the state will ban all new construction including additions to existing structures whether it is a room, adding on to a commercial building, or putting in place an outbuilding such as a barn.
The San Joaquin Area Flood Control Agency — formed by the three cities and the county — is in the process of meeting the state mandate to start 200-year levee work by 2030.
Should a 200-year flood occur with multiple levee failures along the Stanislaus and San Joaquin rivers south of the Interstate 5 bridge before the merger with the 120 Bypass, engineers have indicated it would among other things:
*Flood 20,000 existing homes.
*Endanger and force the overall evacuation of 55,000 residents in Lathrop outside of River islands, Weston Ranch in Stockton, southwest Manteca, and rural areas
*Force the evacuation of San Joaquin Hospital — the county’s major trauma center — as well as the county jail.
*Force first responders at five fire stations, and the county sheriff to abandon their stations and key communication centers in the middle of a major emergency.
*Lathrop High and Weston Ranch High would have water flowing through their campuses as would seven other Manteca Unified elementary schools.
*Force the closure of portion of Interstate 5 — the major West Coast freeway running from Mexico to Canada — and the 120 Bypass.
*Water would swamp the wastewater treatment plant serving 90,000 existing Manteca residents and more than 14,000 of Lathrop’s nearly 34,000 residents.
*Disrupt Union Pacific Railroad train movements as well as damage tracks that Altamont Corridor Express relies on.
And that’s just for starters.
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To contact Dennis Wyatt, email dwyatt@mantecabulletin.com
