Lake Oahe is at its highest level in six years, and that's good news for boaters.

But a state Game, Fish & Parks Department official says the improvement in water levels doesn't come without risk.

Jim Riis says some felled cottonwood trees that were once lying high-and-dry on shore have floated into the Missouri River reservoir.

He says boaters should be on the lookout for those hazards.

Lake Oahe has risen nearly 24 feet since hitting a low-level mark in September 2006.