A 165-year-old British development firm started as an international shipping concern employing clipper ships is on the verge of doing something the State of California has failed to do for the better part of 50 years — reduce the chance of flooding along the San Joaquin River between its confluence with the Stanislaus River and where the Old River splits away.
Somerston’s Holding’s subsidiary — Cambay Group — that is developing the 11,000-home River Islands at Lathrop planned community is working with the non-profit River Partners to acquire a large swath of land needed to widen the Paradise Cut. In doing so it will take pressure off of the narrowest and most flood-prone segment of the San Joaquin River where levees have failed 11 times since 1929 flooding farmland south of Manteca. And now that development has spilled into areas within the City of Manteca that flooded in 1997, the Paradise Cut work will enhance flood protection for thousands of Manteca city residents as well.
At the same time River Islands is committed to bankrolling the work on its side of Paradise Cut to create a 300-foot wide “bench” — a raised area from the edge of the historic flow area to the new levees the development firm has put in place — as well as plant vegetation on portions where it is legal to do so. The bench will be created by leveling the older 12-foot high levee and spreading dirt back toward the new 18-foot high level.
Some of the Paradise Cut bottomland will still be farmed as part of the multi-dimensional project that improves flood control, restores wildland, develops regional recreational use, and creates a permanent greenbelt.
“Swainson’s Hawks like to eat grain,” noted River Islands Project Manager Susan Dell’Osso as she drove along the new levee Friday.
That levee is part of 18 miles of new levees encircling Stewart Tract — the outer Delta island that is now known as River Islands. A segment of the levee work recently completed includes the 300-foot wide super levee along the river that is now viewed as the platinum standard for flood protection by experts. It was created by building a parallel “levee” to the existing levee and then filling the gap with dirt. The approach — born of necessity after River Islands’ permits to enlarge and strengthen the original levee languished in the state and federal review process for years — took advantage of loopholes. At first federal and state flood protection bureaucrats weren’t happy about the end run. Now, however, Dell’Osso said agencies bring others to River Islands to show them what they hold up as “the model” for doing it right.
River Islands submitted paperwork to do the actual Paradise Cut widening work in 2003. They were told it would be an 18-month process. The Army Corps of Engineers is still reviewing the process.
The solution the England -based developer is pursuing essentially affords more than 265,000 San Joaquin County residents protection against the ravages of 100-year-floods and event 200-year events. The 100- and 200-year monikers are a reference in flood lingo not to how often an event will occur by the intensity level. As more of the San Joaquin River watershed is paved over or has roof tops placed on it, the more frequent flooding becomes.
The solution creates a safety valve by widening Paradise Cut to the south from where it branches off the San Joaquin River and passes beneath Interstate 5 just north of the Interstate 205 interchange to where it connects with the Old River.
It is an idea that has been floating around the state Department of Water Resources since the 1980s.
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.
It was included in 2012 as part of the department’s Central Valley Flood Protection Plan. Modeling shows if the seven-mile long Paradise Cut was widened by 1,000 feet to the south, it would lower water levels at Stockton, French Camp, and Lathrop by two feet to enhance 200-year flood protection by directing some water to the south Delta and away from downstream levees.
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, flooded 2,000 homes as well as other structures, forced the evacuation of 2,000 people, and caused property losses in excess of $80 million.
The River Islands’ Paradise Cut 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.
While awaiting Army Corps approval, Cambay agreed to put aside $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.
Dell’Osso said River Islands is involved in the Paradise Cut effort to be a good neighbor and steward of natural resources. To provide strong flood protection for the planned community per se the Paradise Cut widening is not needed.
The Paradise Cut endeavor has been embraced by environmental groups as it would allow the restoration of habitat.
The Paradise Cut project is independent of efforts to secure 200-year flood protection for lands and cities on the eastside of the San Joaquin River from Lathrop/Manteca to Stockton but it would enhance those efforts. That levee work needed has been pegged at more than $160 million.
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 relieve 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.”
Paradise Cut is essentially the last place on the San Joaquin River to create a smaller version of the 41-mile Yolo Bypass of the Sacramento River that successfully stopped perennial flooding of Sacramento.
Paradise Cut would send water around the problematic bend at Mossdale where the San Joaquin River channel narrows. The bend, due to the pressure of water hitting it, is where boils often develop during high water. Boils are a precursor that can signal levee failure can occur.
The widened seven-mile long Paradise Cut would create a permanent greenbelt of at least 1,500 feet in width to separate Tracy and Lathrop.
