Conejohela Flats facts for kids

The Conejohela Flats are a group of islands found in the Conejohela Valley. This valley is a large, flat area along the last 30 miles (50 km) of the Susquehanna River in Pennsylvania and Maryland, USA. The valley became flooded mostly in the early 1900s. This happened because three big dams were built: the Holtwood, Conowingo, and Safe Harbor dams. They were built between 1910 and 1931.

What the Conejohela Valley Was Like

Before the 1900s, the Conejohela Valley was a wet, marshy area. It had many wetlands and thick forests. The Susquehanna River would flood every spring. Bigger, more damaging floods happened about once every ten years. The valley had small waterfalls, fast-moving water (rapids), and marshes.

The river was very wide here. This made it hard for people to cross. Both Native Americans and early settlers found it difficult. This wide river also made it hard to trade goods across the lower Susquehanna. This was a problem for the early colonies of Pennsylvania and Maryland.

Crossing the River

To help people cross, a ferry service called Wright's Ferry started in 1730. Later, the first Columbia-Wrightsville Bridge was built. People once thought it was the longest covered bridge in the world. This wooden bridge was later replaced by stronger steel bridges. These new bridges were big enough for many types of vehicles. The modern bridge opened in 1930. It was later named the Veterans Memorial Bridge in 1980.

Why the Valley Flooded

Three large dams were built across the Conejohela Valley. This happened during the first 40 years of the 1900s. Their main jobs were to create hydroelectric power. This power was used for southern Pennsylvania, including electricity for trains like Amtrak. The dams also helped control the yearly flooding of the river. Another goal was to stop mud and dirt from the flats from flowing into the Chesapeake Bay.

Building the Dams

The first dam built on the lower Susquehanna was the Holtwood Dam. It was finished in 1910. The Conowingo Dam was built next, opening in 1928.

The Safe Harbor Dam had the biggest effect on the river's environment. When its gates closed on September 29, 1931, it flooded over 10 miles of the upper Conejohela Flats. This created a new, artificial lake called Lake Clarke. Most of the valley became covered in water. The few islands that are still left in Lake Clarke are low, marshy areas. They are about five miles north of the Safe Harbor Dam.

Wildlife and Nature

The Conejohela Flats that remain are important homes for many different animals and plants. The varying depths of the flooded islands in Lake Clarke are perfect for many kinds of fish. These include small feeder fish, pan fish (like sunfish), and large game fish that people like to catch. The Safe Harbor Dam area is now a very popular spot for fishing.

The low islands and the areas along the river (called a riparian ecosystem) also support many types of birds. Because of this, the flats are a favorite place for people who enjoy watching birds.