The Upper St. Anthony Falls Lock and Dam have been servicing Minneapolis and the Mississippi River since 1963. But after nearly 52 years, the lock will soon be closed for good.
President Obama signed legislation approving the closure on June 10.
The impact of the closure remains to be seen.
“(The city is) looking at impacts. That's a tough question to answer. Nobody really knows at this point, I guess, on how you quantify that and what would happen. So our headquarters is looking into that question, too, and developing guidance for how to address that and moving forward,” said Chief Archaeologist Brad Perkl of the U.S. Army Corps of Engineers.
The key reason for the lock closure is to stop the spread of the invasive Asian carp species from continuing North. This lock is the Northern-most navigational structure on the Mississippi and the only way carp can advance up the Mississippi past the St. Anthony Falls.
The Asian Carp Regional Coordinating Committee reports that four different species have invaded U.S. waters since they were introduced in the 1960s and 70s. These species were supposed to aid farmers’ aquaculture ponds. About 10 years later, all species were spotted in the wild and have been rapidly swimming north ever since.
The Bighead Carp, Silver Carp and Black Carp are the most dangerous to native habitats. Bighead and Silver Carp are ravenous and consume large amounts of plankton and microorganisms that native fish rely on. They grow to be around 30 to 40 pounds on average but some have been found to weigh 110 pounds. Black Carp only feed on mollusks, but they can still grow to be seven feet long and threaten sturgeon and mollusk populations.
According to the Tip of the Mitt Watershed Council of Northern Michigan, Grass Carp were the first species of Asian Carp that was found breeding in the Great Lakes in October 2013. Although they are seen to be less of a threat, they can still cause harm to the ecosystem because they feed on large quantities of aquatic plants.
Eradication of the Asian Carp may not be possible according to the Asian Carp Regional Coordinating Committee. Asian Carp have no predators because there are no existing North American fish large enough to eat them, so the lock closure may be the best defense against the invasion at this moment in time.
Although the lock’s usage has declined over the years, there are still tons of materials transported up and down the Mississippi each year. Barges transport fertilizer, cement and aggregate and winter road salt up and down the river in immense quantities. Jessica Jones of the U.S Army Corps of Engineers said one barge is the equivalent of 58 large semis or 15 train cars and two barges can fit in the lock at once.
The lock closure will likely lead to an increased cost in these materials due to the transportation costs of trucking and will also increase truck traffic on the freeway system.
The Metropolitan Council estimated that annually 21, 316 more truck trips would be needed to accommodate the closed lock, resulting in a $21.5 million increase in transportation costs to Minnesota’s economy.
On the other hand, without the lock closure, the carp invasion could have a much larger impact on tourism and recreation throughout Minnesota. A 2011 Minnesota Department of Natural Resources (DNR) report stated that Minnesota has the largest rates of boating and fishing participation of any state in the U.S., which draws $4 billion annually. Silver Carp could greatly impact boating because they are startled easily by motors and can leap up to ten feet out of the water at the sound, which can injure people and damage property.