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Tour of the Conejohela Flats

The Conejohela Flats are a combination of low-lying islands and mud flats on the Susquehanna River in Pennsylvania about three miles south of Columbia and Wrightsville, located just offshore from the small settlement of Washington Boro in Lancaster County.

The Conejohela Flats are alluvial islands that develop from the forces of erosion and deposition and the building up of large amounts of sediment (soil, silt, sand, and coal silt derived from upstream coal mining waste), which alters their shape and size. Major floods from severe weather events can dramatically change islands. Ice during the winter devastatingly carves out large chunks of land and soil altering the landscape. The dredging of river channels, construction of dams, pollution and erosion of soil caused by poor agricultural practices, intensive logging of the watershed, and acid drainage from coal mining in the past and still today has harmed natural areas such as the Conejohela Flats and on a greater scale the health of the Susquehanna River and the Chesapeake Bay. An effort has been made in recent years to restore the health of the river and Bay, but much work remains to be done.

The Safe Harbor Dam (located on the Susquehanna River about 6 miles south of the Conejohela Flats) was built in 1931 to generate electricity. With construction of the dam, the river behind it backed up, flooding many of the low areas of land and islands creating the 11.5 square-mile reservoir known today as Lake Clarke. The dam also became a huge trap for upriver sediment that flowed into the shallows of the river, expanding and creating new islands such as the Conejohela Flats.

The operators of Safe Harbor Dam are required by their Federal Energy Regulatory Commission (FERC) license agreement to not raise the water level of Lake Clarke above a certain set amount so that a percentage of mud flats are exposed from April 15-October 15 during the shorebird migration period. Safe Harbor is permitted to increase the water level to generate more hydroelectric power during the non-migration season.

Water Safety

Remember: safe use of rivers and any designated trails, at any time, is your responsibility! Water trail maps are for informational and interpretive purposes only and are not meant for navigational purposes, nor do they take into account level of skills or ability required to navigate rivers. The National Park Service, Chesapeake Conservancy and/or the individual trail associations assume no responsibility or liability for any injury or loss resulting directly or indirectly from the use of water trails, maps or other printed or web-based materials. Learn more about water safety.

Image Credit: Henry T. McLin / Flickr

Navigational Hazards

Paddling the Flats is most suitable for canoes, kayaks, and paddleboards because of the shallow water conditions and chance of becoming stuck. -Mud flats, sand bars, and channels are constantly forming and reforming, there is no set route, making each paddle trip to the Flats a new experience.

Weather is unpredictable and conditions can change quickly and unexpectedly. Always check the weather and water levels. Contact Shank’s Mare Outfitters or check for conditions. -Leave No Trace. Respect nature and wildlife. Enjoy from a distance.

Be aware and respectful of waterfowl hunters. Do not disturb duck blinds.

Pack proper equipment and clothing depending on the season and conditions. Take along plenty of water, binoculars, camera, and bird guide.

Paddlers must adhere to life jacket, sound-producing device, and registration/launch permit requirements. Use light source during dark hours.

For more detailed information on paddling regulations and safety see the Pennsylvania Fish & Boat Commission (PFBC) safety webpage or the Pennsylvania Boating Handbook For PFBC launch permit information and requirements use