More than half of California’s reservoirs are contaminated with high levels of mercury, says the Los Angeles Times. Nine local water boards and state authorities have called for a statewide plan to lower mercury levels in 180 of the state’s 300 reservoirs and warn fishermen that their catch may be poisonous. But mandatory health advisories won’t happen for at least two years. In the meantime, the State Water Resources Control Board is asking reservoir owners to voluntarily post warnings, especially about top-of-the-food-chain species like bass, which are more likely to carry the neurotoxin in their tissues than species that feed primarily on algae and other plant material.
Bass is also a major draw to sport anglers, who bring in significant tourism and recreational dollars each year. Reservoir owners routinely stock their waters with the species to attract more sport fishermen. But state officials would rather see owners add more rainbow trout and crappie, which, because they are lower on the food chain, bioaccumulate less mercury. Some fishermen suspect that the real aim of the mercury campaign is to malign bass, since the non-native species often feeds on protected and endangered native fish.
Most of the mercury found in California’s waterways and fish comes from coal-fired power plants in developing nations, where anti-pollution technology is often outdated. “When released into the air, mercury travels great distances, contaminating oceans, lakes and rivers,” says the Times.