The Salinas Valley Basin Groundwater Sustainability Agency (SVBGSA) on Thursday outlined a multi-hundred-million-dollar plan to halt worsening seawater intrusion by treating and pumping water back into the basin to create a protective barrier. No vote was taken, but the presentation put a spotlight on the project’s price tag — estimated between $700 million and $1 billion — and the unresolved question of who pays. … Agency leaders said recent studies show intrusion is more severe than previously understood, threatening municipal supplies and the region’s agriculture if left unchecked.