Wing dam

The Mississippi River in North America has thousands of wing dams which were originally constructed to reduce the amount of dredging required when the main navigation channel was maintained to at least 4+1⁄2 feet (1.4 m).

Since that time, additional conventional dams have been built to increase the water level in the river, doubling the depth of the navigation channel to 9 feet (2.7 m).

[1] While wing dams assist in assuring that rivers are navigable, they can also pose a threat to boaters.

[2] On the other hand, fishermen intentionally fish the quieter waters downstream of wing dams.

Some researchers believe that flooding is increased by wing dams; a 2013 theoretical analysis predicts that wing dams may lead to water level lowering for in-bank flows and to water level increases for out-of-bank (flood) flows.