More By allowing ads to appear on this site, you support the local businesses who, in turn, support great journalism. MORE HOMES BEING BULT IN FLOOD ZONE New homes fees will cover part of cost of $180M levee upgrades 10-12 years away This overlay on a flood map shows much of southwest Manteca would be covered with 3 to 5 feet of water in the event of a 200-year flood — larger than the 100-year event in 1997. The orange line is the existing dry levee while the red line is its extension. Twenty-four years ago today Manteca was breathing a collective sigh of relief that the flood that devastated 70 square miles along the San Joaquin River forcing 2,000 rural residents to flee left the city intact.