Lock and Dam 3 Fish Passage Habitat Rehabilitation and Enhancement Project        

St. Paul District

Lock & Dam 3, Upper Mississippi River, Mile 797, Pierce County, Wisconsin, Congressional District: WI - 3




Habitat connectivity is essential to fulfilling seasonal and life stage-specific habitat needs for river fishes. Dams like Lock and Dam 3 reduce the connectivity of aquatic habitat by restricting movements of river fishes in addition to other effects of impoundment and river regulation. Impeded fish movements resulting from dams have been implicated in altered fish community structure and declines of many fish populations in rivers throughout the world (Northcote 1998, Pringle et al. 2000). Each migratory fish species has its own behavioral response to environmental cues for initiating migrations. Many fishes undergo pre-spawning migrations to spawning habitats, spawn in the spring, disperse to feeding habitats, and migrate to winter habitats in the fall. The timing of these movements varies considerably between species, and appears to be generally controlled by water temperature, photoperiod, and river flow. The timing of upriver runs of migratory fishes often does not correspond to times when the dam gates are open, thereby limiting access to upriver habitats. Restrictions on movements of migratory fish in a river system limit the extent and quality of habitats that they can occupy. Effects of reduced access to habitats can be expressed at the individual, population, and community levels. Many of the migratory fishes in the UMRS have declined in abundance in the seven decades that most of the navigation dams have been in place. The declines in abundance of skipjack herring and Alabama shad following construction of the Keokuk dam in 1913 (Coker 1929) were clear examples of population-level response to restricted range of migration. Restricted movements of fish between navigation pools may restrict gene flow within mussel species dependent on a single fish species as their glochidial host (Romano et al. 1991). Large spawning aggregations of migratory fish may once have played a key role in the life history and reproductive success of Unionid mussels in the UMRS.

Quick Facts

  • Approximate Acres: 660
  • State(s) Covered: WI
  • Land Ownership: U.S. Army Corps of Engineers
  • Management Agency: U.S. Army Corps of Engineers 


  • Alternatives for improving fish passage at UMRS navigation dams were examined in Wilcox et al.
  • Alternatives include assisted fish lockage, dam operation modifications, technical fishways,
    nature-like fishways, smaller-scale fishways through dam embankments, and large-scale fishways.


  • The Fact Sheet was approved in September 2010.