The
associated performance criterion is to provide year-round fish passage for native migratory fishes through
Locks and Dams 2 and 3 by 2025.
An impending threat to the northern reaches of the Upper Mississippi River ecosystem is the invasion of
Asian carp. Asian carp (bighead and silver carp) have established reproducing populations in Pool 18,
north of the high hydropower dam at Lock and Dam 19 at Keokuk Iowa. Individual bighead carp have
been found as far north as Lake Pepin, just downstream from Lock and Dam 3. Asian carp are large,
strong-swimming fish that can swim upstream through most of the Upper Mississippi River navigation
dams either through the dam gates during periods of high river discharge or through the locks during the
navigation season. Unfortunately, there are currently no effective barrier technologies that would prevent
the eventual invasion of Asian carp into the upper river.
A properly designed fishway at Lock and Dam 3 would probably not have any effect in speeding the
invasion of Asian carp northward into Pool 3 but would contribute to larger and more resilient native fish
populations. A fishway at Lock and Dam 3 will be designed with a water control structure at the upstream end to allow the fishway to be closed when large aggregations of Asian carp are in the tailwater.