Clark County Public Health conducted more testing at Vancouver Lake on Monday to check on toxin levels in the water.
On July 20, the lake was placed under a caution advisory due to the presence of blue-green algae.
Blue-green algae is covering most of the lake now, according to Public Health, including the swim beach and other popular access points.
Public Health is asking people to avoid contact with water that is green, discolored or murky. Contact includes swimming, wading, kayaking, paddling and rowing.
Pets should also avoid contact with the water, as blue-green algae can be deadly to small animals that drink the water.
Public Health expects to have test results back later this week.