LOW-HEAD DAM BASICS
Low-Head Dams in the U.S.
Low-head dams in the U.S.
Low-head dams are found throughout the U.S., with more than 13,000 low-head dams identified nationwide. The highest densities are in Maryland, Pennsylvania, New York, and central New England. While not every waterway has a low-head dam, they are widespread and important to recognize.
Recognizing low-head dams
Sometimes the smaller height of the low-head dam and relative calm of the nearby water makes them more difficult to recognize. Often, these dams are easier to see looking upstream, since there is usually a visible drop as water flows over the dam and downstream. Knowing what these dams look like can help people identify them, and avoid them when swimming, fishing, or kayaking and boating.
Fort Dodge Little Dam was located on the Des Moines River in Iowa. When built, it reached from one side of the river to the other. Upstream, the dam was barely visible except for a protruding concrete knob. The dam was easier to see downstream.
Peery's Mill Dam is located on the Little River in Blount County, Tennessee. It reaches from one side of the river to the other. A mill and the remains of its site are located on the north side of the dam. Water enters an outlet structure formerly used for a wood turbine located on the backside of the dam. Warning signs were not installed until 2019, when a 13-year-old girl drowned at Peery's Mill Dam.
The Monroe Drop Structure is part of the Long Tom River channel rectification project in the Willamette Valley, Oregon. The project was completed in 1950 after the construction of Fern Ridge Dam upstream in 1941. The structure is shown below after construction (left) and in its current condition (right). As described on the sign near the structure, the recirculating currents below the submerged dam can trap boaters. There are signs upstream and downstream of the dam to warn boaters.
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