If you live in a developed part of Lathrop, there’s a very good chance that you have better protection than most when it comes to protecting your home from the rising waters of the San Joaquin River.
According to a release issued last week by the City of Lathrop, the portions of the city that have the largest concentrations of homes are also protected by levees capable of at least withstanding a 100-year flood.
And if you’re a River Islands resident, you’re in even better shape. The developed portions of the master planned community along the San Joaquin River have for 10 years been protected by 300-foot wide levees that are capable of withstanding 200-year flood water levels, which is the new standard for all development within a flood plain area.
In the report City Manager Steve Salvatore informed residents that Lathrop is not currently in danger of flooding with the river as it flows through the community sitting well below flood stage for anybody who lives on the eastern side of the levee.
Some low-lying areas adjacent to the levee have had seepage issues – the byproduct of high water raising the surface water table and not traditional flooding – and at least one Lathrop neighborhood built on the river side of the levee, Haven Acres, has had as much as three feet of water inside of the mobile homes.
And even though Reclamation District 17 has been doing some work in Lathrop – including building a seepage berm – Salvatore said that the work is not reflective of underlying problems with levee integrity like has been seen in some adjacent areas.
The areas to the south of the Union Pacific Railroad tracks and the undeveloped portions of River Islands are both protected by rural levees, which offer only 50-year flood protection and would be vulnerable to high water.
But with Lathrop’s place along the reworked channel of the San Joaquin River – the San Joaquin originally flowed along the “Old River” route through Tracy and eventually into the Delta above Antioch but was rerouted for navigation and flood control purposes in the late 19th and early 20th centuries – a large portion of the water that is currently threatening levees in South Manteca and rural Tracy will never flow passed the community as it continues along the Old River route and into the Paradise Cut Inlet.
While the likelihood of flooding in developed Lathrop is low at this point, the conditions of the river could change – especially with a record snowpack in the watersheds above the reservoirs that feed the San Joaquin River – and the city urges residents to remain current on information and be prepared to evacuate if the unexpected were to happen.
In addition to having clothes and personal effects handy, emergency personnel also urge people to make sure that their vehicle is gassed, necessary medication is readily available and an emergency supply of cash is also on hand.
The San Joaquin River at both Vernalis and Mossdale is expected to decline over the course of the next week now that the spillway at Don Pedro Reservoir has been closed.

To contact reporter Jason Campbell email jcampbell@mantecabulletin.com or call 209.249.3544.