Lock and Dam number 3

 dam, lock (water navigation)

This is lock and Dam number 3 on the Mississippi it is a navigation dam and lock on the Mississippi River 6 miles upstream from Red Wing, Minnesota. Its position on a bend in the river makes downbound navigation difficult, because of an outdraft current that tends to sweep towboats and barges away from the lock toward the gated part of the dam. The outdraft current has resulted in many accidents, including 11 incidents since 1968 when tows collided with the gated part of the dam. A related problem is with the low and weak embankments on the Wisconsin side. Navigation accidents can render the 4 roller gates inoperable, resulting in overtopping and erosion of the embankments. The three Wisconsin side embankments divide the 8-foot head at the dam into three steps and work together as part of Lock and Dam 3. Failure of the embankment system could result in accidental drawdown of Pool 3 with significant economic and environmental consequences.