<P> Less - obvious barriers were the rivers crossing the canal, particularly the Chagres (which flows strongly during the rainy season). Since the water would be a hazard to shipping if it drained into the canal, a sea - level canal would require the river's diversion . </P> <P> The most serious problem was tropical disease, particularly malaria and yellow fever, whose methods of transmission were unknown at the time . The legs of hospital beds were placed in cans of water to keep insects from crawling up them, but the stagnant water was an ideal breeding place for mosquitoes (carriers of the diseases). </P> <P> The project was plagued by a lack of engineering expertise . In May 1879, an international engineering congress led by de Lesseps convened in Paris . Of its 136 delegates, only 42 were engineers; the others were speculators, politicians and friends of de Lesseps . </P> <P> He was convinced that a sea - level canal, dug through the mountainous spine of Central America, could be completed at least as easily as the Suez Canal . The engineering congress estimated the project's cost at $214 million; on February 14, 1880, an engineering commission revised the estimate to $168.6 million . De Lesseps reduced this estimate twice, with no apparent justification: on February 20 to $131.6 million and on March 1 to $120 million . The congress estimated seven or eight years as the time required to complete the canal; de Lesseps reduced this estimate to six years (the Suez Canal required ten). </P>

Why did the united states decide to try to build a canal across panama instead of nicaragua