Josh Hill, a marine biology teacher at Mar Vista High School, lost count of the number of times he’s gotten sick from swimming in the ocean at Imperial Beach. “It’s just kind of sad that we have this awesome natural resource that we don’t get to use,” he said. He and a group of students are raising awareness about water pollution by taking weekly water samples of the ocean and publishing their results online. Every Thursday, Hill and his students collect water from the south end of Seacoast Drive and the Imperial Beach Pier.