The San Joaquin River that is imperiling farms in South Manteca and roughly 40,000 residents in Lathrop and Weston Ranch would be less of a threat today if it wasn’t for the state and federal bureaucracy.
Modifications of the Paradise Cut that runs under Interstate 5 between the Manthey Road interchange and the Interstate 205 junction — a solution that an Army Corps of Engineers’ study determined would significantly reduce pressure on levees by lowering water level by 1.8 feet — could have been started as early as 2005 and funded by Cambay Group, the developers of River Islands at Lathrop.
When Cambay Group filed for a permit with the Army Corps of Engineers in 2003 to modify Paradise Cut, they were told the review process would take 18 months. Fourteen years later the Army Corps is reportedly nearing the end of the review process as the five reclamation districts battle around the clock to prevent a catastrophe from happening.
Many people who live and farm east of the San Joaquin River and south of Manteca were under the impression River Islands were supposed to have done the work years ago. They made that point during a Manteca City Council meeting in early 2016 regarding the proposal to spend $168 million to make levee improvements to meet a state mandate for 200-year flood protection. River Islands wanted to do the work a decade ago but the bureaucratic review process with the state and federal government has stretched out the government’s own timetable by 12.5 years.
Paradise Cut widening
would lower river by 1.8 feet
Paradise Cut has historically taken pressure off the San Joaquin River when it nears flood stages. It has little water in it much of the year.
River Islands’ proposal is to add 200 acres to the 600 acres that are within Paradise Cut that runs from the main river channel prior to it reaching Mossdale Crossing and runs parallel to the Middle River Channel. They also want to restore habitat.
The River Islands project is based on a proposal made years ago that resurfaced in 2001 in an Army Corps of Engineers report to create a river bypass to reduce the potential for flooding in Manteca, Lathrop, and Stockton.
The Lower San Joaquin River Flood Bypass proposal was formally submitted to the California Department of Water Resources in March 2011 by the South Delta Levee Protection and Channel Maintenance Authority and other partners. It was an effort to secure $5 million to create the new flood bypass in the last corridor of undeveloped land between Tracy and Lathrop.
Engineers determined expanding the Paradise Cut would reduce flood stages significantly at Mossdale Crossing — 1.8 feet under a 50-year event as well as under a 100-year event such as the 1997 flood that inundated 70 square miles between Manteca and Tracy.
At the same time it would offer habitat and migration territories for juvenile steelhead, salmon and spawning split tail that are driving some water use debates.
It would also allow upstream reservoirs such as Don Pedro and New Melones to be managed more conservatively to reduce water releases during the rainy season and spring runoff to conserve water for summer use.
State expert: Futile to
keep raising levees
David Kennedy, the longest serving director of the Department of Water Recourses, in 1998 wrote the following about the Paradise Cut bypass proposal in the forward of the second edition of “Battling the Inland Sea”: “Recognizing the futility of simply raising the levees, flood control experts will now evaluate the feasibility of removing levees in some locations and simply letting future flood flows pond onto adjacent lands. Further, consideration is being given to opening up some form of bypass through the south Delta to relive pressure on the levees as the San Joaquin River flows into the Delta. It is hoped these issues will be resolved and changes will be made before the next flood.”
That may turn out to be wishful thinking now that the same conditions that led to the 1997 flood that covered 70 square miles south of Manteca — heavy snow melt, reservoirs filled to the brim, heavy rain and wind, as well as statured levees — exist again.
Cambay Group wants to set levees back on the north side of Paradise Cut as well as on the south side. They provided $700,000 for land acquisition and agreed to spend money to do the necessary work that was pegged at between $1.8 million and $3 million six years ago.
The levees stretching from the confluence of the Stanislaus River north to the French Camp Slough are now under around the clock inspection patrols are part of four different reclamation districts — River Junction, McMullen, Walthall, and Wetherbee.
River Junction is at the confluence of the Stanislaus and San Joaquin rivers is always hammered hardest due to its location. Walthall and Wetherbee protect rural enclaves just outside of Manteca at the western end of Woodward Avenue. McMullen covers the area between those two areas and River Junction.
Government gave RD-17
levees split decision in 2010
Reclamation District 17 oversees the levees from a point midway between Mossdale and the San Joaquin River’s confluence with the Stanislaus River to French Camp Slough on the northern edge of Weston Ranch. That is the key reclamation district that protects Lathrop and Weston Ranch. It also involves where the river bends at Mossdale where water pressure pounds the levees.
The federal government in 2010 gave a split decision to the effectiveness of the Reclamation District levees. The Federal Emergency Management Agency granted the levees 100-year flood accreditation a week after the Army Corps of Engineers said RD-17 was among seven of the 10 Central Valley levees they inspected did not meet federal safety criteria and could be threatened in a flood or storm. The Corps conducts Central Valley levee system inspections every five years with engineers literally walking them.
It was the same year RD-17 was awarded $62.4 million in state bond money to strengthen levees.
The work funded was designed to maintain protection against a 100-year flood event and go a long way towards 200-year protection. The 100-year and 200-year monikers are a bit misleading as they are described as flooding that has a chance of happening every 100 years based on natural conditions. As more valley soil has been paved or built on run-off has increased significantly reducing the times between major flooding.
The money was wedded with $1 million raised from a $37 parcel tax assessment over five years that a majority of 4,000 home owners in Lathrop, Weston Ranch, and the extreme southwest edge of Manteca voted to put in place. The parcel tax made it possible to secure the state bond money.
The parcel tax also allowed the district to secure a $10 million U.S. Army Corps of Engineers grant to improve flood protection for a large swath of land generally west of Interstate 5 from Mossdale north to Weston Ranch and a large chunk of the developed portion of the City of Lathrop.
The work involved building a series of berms next to 21 crucial spots in the levees. The 50-foot long by 4-foot high berms will serve to strengthen the levees if water manages to seep through.
River Islands at Lathrop has resolved their flood concerns by creating 300-foot wide levees at a cost of $70 million to take 900 acres on Stewart Tract out of the floodplain.
In addition River Islands pent $2 million on studies to prove to the state that the levees created in 2006 provide 200-year flood projection as mandated by Senate Bill 5.
The last floods were in 1997 when roughly a dozen breaks along the San Joaquin and Stanislaus rivers ended up flooding 70 square miles, damaging more than 800 structures, forcing 2,000 people to flee, and ultimately caused $100 million worth of damages.
The Army Corps of Engineers spent $2 million to patch the existing levees after the 1997 flooding to restore them to the same condition they were in prior to the failure.
The biggest recorded flood in modern South County history started in 1950. It caused flooding west of present-day Interstate 5 in Lathrop. Flood waters threatened San Joaquin County Hospital and came within four miles of downtown Manteca. There were 2,000 people evacuated. Today, if the same flooding occurred, it would force 40,000 people to flee.
To contact Dennis Wyatt, email email@example.com