Bacteria levels in beach water are monitored at 45 public beaches in Virginia on the Chesapeake Bay and Atlantic Ocean during the swimming season (May-September). Water samples are collected weekly by Local Health Departments and analyzed by local laboratories for enterococci bacteria. If bacteria levels exceed Virginia’s Beach Action Value of 104 MPN/100 mL of water, a swimming advisory is issued (MPN=most probable number, a unit for bacteria measurement).
For full information on beach monitoring practices and bacterial monitoring, visit the Virginia Department of Health's website.