TAHOMA — Divers have started laying barriers in Emerald Bay as part of the largest Asian clam eradication project in Lake Tahoe’s history.The $810,000 Lake Tahoe Aquatic Invasive Species program aims to eliminate a 5.5-acre population of Asian clams from the mouth of Emerald Bay and control the invasive species whose numbers have grown exponentially since 2002, when the first clamshell was discovered on a beach. For the next four to six weeks, crews will line the area with thin rubber barriers and organic material from Aspen trees to cut off the clams’ supply of oxygen.The isolated population in Emerald …