Pact Is Signed to Protect Great Lakes The United States and Canada signed an accord in Washington on Friday to protect the Great Lakes, the world's largest freshwater system. The agreement, which updates promises between the two nations first made in 1972, sets goals for each country to address invasive species like the Asian carp; curb phosphorus runoff, which can contribute to algae blooms; and cut pollution from industry and vessels. Each nation will now need to develop policies to implement their common objectives, according to the agreement.