Manteca leaders will need to decide whether they want to pursue dry levees or essentially declare areas south of Peach Avenue and west of Union Road off limits for future urban expansion.
New federal and state guidelines require cities to enhance protection for land designated in 100-year- floodplains or else leave it undeveloped.
“We have to decide either to protect it or we’re not going to develop it,” Community Development Director Frederic Clark told the council during a mid-year budget session on Thursday.
Regardless of what decision Manteca’s elected leaders ultimately make, it will have major ramifications.
If the council elects not to pursue levees, it would significantly reduce the city’s potential to expand south. Should that happen, it would require the city to make buyers of other homes yet to be built to shoulder more of the cost of four interchange improvements along the 120 Bypass - including the proposed interchange at McKinley Avenue as well as the new Austin Road interchange. The combined cost of all the interchange work has been pegged as high as $200 million.
It would also impact the alignment of the extension of McKinley Avenue that generally would head south from the 120 Bypass and then swing east to a new Austin Road interchange on Highway 99.
Not building the levees could ultimately mean less traffic on Union Road and Airport Way than would be generated if thousands of additional homes could be built in the 100-year floodplain.,
If dry levees are built, it would eventually seal the fate of the semi-rural character of the area as well as farming in general as urbanization would be allowed to occur.
Should the city opt to go with levees it would have to work to some degree with Reclamation District 17. Since they would be dry levees, the city could put an assessment mechanism in place to pay for their construction. The biggest problem, though is deciding where they will go and how to secure the land.
It is highly likely that whatever location would be picked for a dry levee that not everyone is going to want it going across their property. That could set the stage for a stalemate unless the city opted for cantankerous eminent domain proceedings, something elected leaders have had little stomach for in the past.
Since there are a lot of five and 10 acre rural estates closer to Manteca, the odds are the city would have to go farther south into working farm country to find a location that may have less opposition. In doing so, the city would be tapping into prime farmland that creates other policy issues.
Sixteen years have passed after the 11th major levee break since 1927 on the San Joaquin and Stanislaus rivers threatened rural Manteca, part of the city as well as Lathrop. The 1997 break flooded 60 square miles between Manteca and Tracy and left parts of Wetherbee Lake homes under water for months. The area is all west of Union Road and south of Peach Avenue.
Voters approved over $1 billion for flood protection work in the area – Proposition 13 in 2000. All of the money, though, was “borrowed” to help the state cover deficit spending.
Save for emergency repairs made by the Army Corps of Engineers immediately after the 1997 flood and a potential breach six springs ago that simply restored the levees to their pre-flood conditions, nothing has been put in place to enhance levee durability on the weak Manteca side of the San Joaquin River near the confluence of Stanislaus and San Joaquin rivers.
Work has been completed, though, on upgrades being paid for by special property tax assessments along the San Joaquin designed to protect southwest Manteca, Lathrop, and Weston Ranch.
Nothing, though, is being done on the Stanislaus River. If a levee fails there it can trigger a domino effect on dry levees between that river and Manteca.