Thick jets of processed sewage arc out 30 to 40 feet from giant moving spreaders at Birmingham Farm in Kansas City, Mo. Frank Morris for NPR hide caption

itoggle caption Frank Morris for NPR

Algae blooms in the mouth of the Elizabeth River in Norfolk, Va., on July 31, 2010. Rain, high temperatures, and pollution from agricultural runoff made for ideal algae bloom conditions. Morgan Heim/AP hide caption

itoggle caption Morgan Heim/AP