Many Americans know the name Kesterson as the California site where thousands of birds and fish were discovered with gruesome deformities in 1983, a result of exposure to selenium-poisoned farm runoff. Thirty-five years later, it is one of the oldest unresolved water problems in the state. Selenium, a naturally occurring element, is essential to people and animals alike in small doses. But selenium continues pouring off many San Joaquin Valley farms in larger quantities, which can be toxic.