SALEM, Ore. -

Due to less snowpack and lower rainfall this winter, many Oregon lakes and rivers will be reaching historically low levels, which will expose previously unseen hazards to boaters this summer, state officials warned Thursday.

Stumps, rocks, logs and other obstructions could be just below the surface, resulting in hull or prop damage in areas that are normally navigable.

These obstructions also impact the water dynamics and the currents in rivers, which can increase the difficulty to navigate safely, especially for paddlecraft.

The state Marine Board is urging boaters to plan ahead and take the time to scout area waterways before launching your boat.

"No matter where you boat, most of our rivers and lakes will have obstructions that may not have been a problem earlier in the summer." says Ashley Massey, public information officer at the Oregon State Marine Board. "Water levels are changing quickly, so boaters need to assess the waterway each time they go boating."

Boaters can check the Marine Board website to see what's been previously reported, but that does not take the place of scouting ahead once at the river, and having a plan if you do encounter an obstruction you cannot safely navigate or portage around.

Trees, root wads and other natural debris are a common part of Oregon's rivers and streams, providing important ecological benefits such as fish habitat, sediment removal, etc. and can be very dangerous to boaters.

Deadheads (old pilings or logged tree stumps) may lie just below the surface, so keep a close watch for subtle changes in the water's surface. Strainers (trees hanging out from the bank) can trap a boat and the current could force it underwater.

Officials advise boarders to keep a sharp lookout downstream and use a quick-release anchor system for just such emergencies. Motorized boaters should operate carefully and pay particular attention to the surface dynamics ahead of where they're headed, especially while on-plane.

If paddling on rivers with whitewater rapids, any rapids designated as a Class III or higher, boaters are required to wear a properly fitting, U.S. Coast Guard approved life jacket.

Not sure where to put in or take out? Visit the Marine Board's Boating Access Map to help plan your trip at http://www.oregon.gov/OSMB/pages/access/access.aspx#Where_to_Launch_in_Oregon.

For reported navigation obstructions, visit http://www.oregon.gov/OSMB/Pages/safety/navigation_hazards.aspx.