Under a 2007 mandate from Congress, the Army Corps of Engineers conducted a two-year study, called the Great Lakes and Mississippi River Interbasin Study, of the problem of Asian carp entering the Great Lakes via Chicago's web of waterways. Asian carp are known as a "nuisance species" that quickly gobbles up the plankton, thereby threatening the food source of the sport fish in the lakes. Conservation groups want the Corps to block the accessways as quickly as possible, but sports fishers and commercial shipping companies worry that the impact of blocking the flow of the waterways will have on the lakes. The Corps' 210- page study estimates the cost of blocking the waterways at $18 billion. Explain what needs to be done under these circumstances and how the Corps should proceed.

(Michael Wines, "$18 Billion Price Put on Effort to Block Carp," New York Times, January 7, 2014, p. A10.)