A tar ball from the Deepwater Horizon oil spill washed ashore near the Treasure Island subdivision in Lake Pontchartrain as people fish near the Rigolets in Slidell, Monday July 5, 2010. MATTHEW HINTON / THE TIMES-PICAYUNE

By Matthew Hinton, The Times-Picayune
Posted: Monday, July 05, 2010, 8:06 PM A tar ball from the Deepwater Horizon oil spill washed ashore near the Treasure Island subdivision in Lake Pontchartrain as people fish near the Rigolets in Slidell, Monday July 5, 2010. MATTHEW HINTON / THE TIMES-PICAYUNE

Oil has reached Lake Pontchartrain