It has a 1 in 200 chance of happening.
But 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, it would create a soggy Armageddon of sorts that would:
uflood 4,200 existing homes with 3 feet or more of water.
uendanger and force the evacuation of 10,698 residents in Lathrop outside of River islands, Weston Ranch in Stockton, and southwest Manteca.
uforce the evacuation of San Joaquin Hospital — the county’s major trauma center — as well as the county jail.
uforce first responders at nine fire stations, the Lathrop Police Department and the county sheriff to abandon their stations and key communication centers in the middle of a major emergency.
uLathrop High and Weston Ranch High would have water flowing through their campuses as would six other Manteca unified elementary schools.
uforce the closure of portion of Interstate 5 — the major West Coast freeway running from Mexico to Canada — and the 120 Bypass.
uwater would swamp the wastewater treatment plant serving 75,000 existing Manteca residents and more than 13,000 of Lathrop’s nearly 20,000 residents.
udisrupt Union Pacific Railroad train movements as well as damage tracks that Altamont Corridor Express relies on.
u182 commercial and industrial properties from Costco to the Lathrop Target and Tesla Motors to Simplot would be flooded.
And that’s just for starters. Modeling shows a number of existing homes would likely suffer water damage in fringe areas that could receive upwards of three feet of flood water.

Manteca certifies
adequate progress
for levee work
Manteca Councilman Mike Morowit Tuesday noted that while much of the talk has been about providing flood protection for future growth it is about protecting existing residents.
“We have kids involved and a hospital,” Morowit pointed out.
Morowit added if a 200-year flood did occur “there is a safety element to this (for existing residents) that we sometimes forget about.”
Morowit made his comments prior to the council adopting a series of documents to demonstrate to the state that Manteca is making adequate progress toward providing a 200-year urban level of flood protection in Reclamation District 17 as mandated by Senate Bill 5.
It is an annual exercise the city will have to perform — as long as they have the data or work in place to back up their declaration — every June until 2025 when the actual levee work has to be completed.
Tuesday’s council presentation provided a new number for the estimated costs of flood protection. It is now pegged at $200 million as opposed to previous estimates of between $170 million to $180 million.
Critics of the levee project such as longtime farmer Michael Fonseca who has 30 plus acres that may needed for an extended dry levee that serves a back-up when river levees break warm that the estimate may not include the price of land the city working with Reclamation District 17 would have to take to make the levee work.
Fonseca made a pitch to the council to “do the right thing” and take the proposed Raymus Express  off the table  permanently instead of just during the levee alignment debate in a bid to reduce opposition from people who may have either the levee, the expressway or both ultimately slice though their property.
“City politics thrive by sweeping confrontational issues under the rug and hiding behind consultants,” Fonseca said.

Levee work cost
now pegged at $200M
Manteca, Lathrop, and Stockton aren’t the only communities impacted by the Senate Bill 5 mandate. There are 85 cities in 33 Central Valley counties that have to comply.
Not spending what is now estimated to be $200 million would cost Lathrop, Manteca, and San Joaquin County billions upon billions of economic losses due to the state dictating those that don’t comply will not be able to continue urbanizing within 200-year floodplains.
Council members were also told a decision by the Army Corps to take Reclamation District 17 out of future Lower San Joaquin River flood control studies is making the $200 million levee project ineligible for federal assistance and as a result could jeopardize and y chance of state funding.
That means the $200 million cost would have to be spread out among 4,600 existing homeowners, 182 commercial and industrial properties as well as any future growth within the 200-year floodplain.
Critics have pointed to other flood protection solutions such as dredging between the confluence of th4e Stanislaus and San Joaquin rivers and Mossdale Crossing. Years ago the river during that stretch was deep enough to move barrages of grain. Silt build-up has now made such river movements impossible. Federal and state bureaucracies have made it clear that is not an option.
At the same time the 200-year flood protection model is not being allowed to take into account work in nearby areas including the widening of the critical Paradise Cut that serves as a pressure valve relief for high water on the San Joaquin River. River Islands has gained approval to widens the cut and restore the environment but has yet to been given the final permits to begin work.
Critics also noted the state required a model that has as many as nine levee breaks south of Manteca with no other level breaks occurring elsewhere to take pressure off local levees. Such a scenario is considered virtually impossible to happen but those bureaucrats implementing Senate Bill 5 in Sacramento had said flood protection must be based on such a scenario.