President Fawn Sharp said Tuesday the emergency measure is aimed at protecting water quality in the tribe-owned lake.
She said tribal leaders are concerned leaky septic tanks owned by non-tribal residents in the area may have caused untreated sewage to get into the lake. The tribe has detected pollution in some areas of the lake and plans to conduct more water quality tests.
Sharp said the tribe plans to monitor any fish caught by tribal members. She said they are also worried about reports of illegal fishing by non-tribal members and docks being built illegally on the lake.
The lake is located on the southwestern edge of Olympic National Park.