A Dallas-based engineering firm is being tapped to help design California’s plan to bolster its water supply system. Jacobs’ initial $93 million contract is for preliminary and final engineering design of a 15-year program known as California WaterFix. The Golden State’s largest water conveyance project carries a $17 billion pricetag. WaterFix, slated to begin this year, will upgrade 50-year-old infrastructure dependent on levees, which the state said puts clean water supplies at risk from earthquakes and sea-level rise.