Testing for lead in water systems at San Diego Unified School District campuses began Monday, according to district officials. The testing program comes a couple of months after elevated levels of lead, copper and bacteria were discovered at three campuses in the San Ysidro School District. Testing previously took place at Emerson-Bandini Elementary School in Southcrest after a nurse saw a therapy dog reluctant to drink the water — which turned out to contain a variety of contaminants, including lead, according to multiple news reports.