Santiam Lake is a lake in the U.S. state of Oregon, west of Three Fingered Jack in the Cascade Range. It is headwaters for the North Santiam River and drains a portion of the southwestern Mount Jefferson Wilderness. The lake is stocked bi-annually with Brook and Rainbow trout. It can be accessed from various trails in the Jefferson Wilderness, including S…Santiam Lake is a lake in the U.S. state of Oregon, west of Three Fingered Jack in the Cascade Range. It is headwaters for the North Santiam River and drains a portion of the southwestern Mount Jefferson Wilderness. The lake is stocked bi-annually with Brook and Rainbow trout. It can be accessed from various trails in the Jefferson Wilderness, including Santiam Lake Trail #3491. It is located about 6.5 miles northwest of Santiam Junction, Oregon.