Beachgoers in Coronado – one of California ’s ritziest beach towns – are being greeted by bright yellow “water contact may cause illness” signs as sewage from Mexico continues to force closures ahead of peak summer. The contamination is largely tied to the Tijuana River, which carries untreated wastewater from Tijuana, Mexico, into the Pacific Ocean . From there, currents push polluted water north along the beaches of southern San Diego County, including Coronado. As much as 30 million gallons of sewage-tainted water can flow into the ocean daily, overwhelming the region’s ability to maintain safe beach conditions, the Wall Street Journal reports. Since 2018, more than 10 billion gallons of raw sewage have flowed into the Tijuana River, according to the International Boundary and Water Commission. “It was heaven on earth and now I call it paradise lost,” Whitney David, a retired surgeon and surfer, said. He told the outlet he ultimately left Coronado largely due to the ongoing sewage problem.…