San Diego County residents will have an opportunity to share their pollution concerns about the Tijuana River when officials from the Centers for Disease Control and Prevention arrive later this month to conduct a health survey. This is the first time that a federal agency is investigating the potential harm caused by millions of gallons of raw sewage pouring through the Tijuana River that have caused beach closures of more than 1,000 days. Residents living near the river say they have been suffering unexplained illnesses, including gastrointestinal issues and chronic breathing problems, because of the stench of hydrogen sulfide.