San Luis Reservoir in Merced County - one of California's largest artificial lakes - not only irrigates Central Valley farmland and supplies drinking water across Silicon Valley and the South Bay, but also draws swimmers, boaters and anglers year-round.
Yet for months at a time, forest-green blankets of algae spread across the lake's surface. Despite their calm appearance, these harmful algal blooms, or HABs, can disrupt water supplies, ecosystems and recreation activities - and pose serious health risks.
