The natural obstacles to navigation at the bar of the river have led the Government of Columbia at different times to expend considerable sums of money in trying to open a canal from the river at Calawar to Carthagena, known as the Dique. The project has not, however, been very successful. The distance of this route is about 90 miles, and, although the four steamers employed upon it by the Dique Company have been tolerably successful, a large expenditure is said to be still required to complete the means of transport. As it is, the Government have dredges constantly at work on this artificial waterway. The Government are, moreover, canalising the river throughout its entire length, the cost being defrayed by charges on the traffic, which is steadily increasing.[124] The _Desague Real de Huchuetoca_.—This is a vast drain or cut that has been carried through the Cordilleras, that surround the Valley of Tenochillan, or Mexico, at Nochistongo, for the purpose of getting rid of the dreadful inundations which almost periodically came upon the city of Mexico. The Section of the Desague, for a considerable distance, is from 1800 to 3000 square metres (19,365 to 32,275 sq. feet). Its length from Vertideres to the Salts is 20,585 metres, or 67,535 feet. Near the old well of Don Juan Garcia, at the point where the ridge is highest, the cut in the mountain extends for a length of more than 2624 feet, to between 147 and 196 feet in perpendicular depth. For a length of over 3000 feet more, the depth of the cut is from 98 to 131 feet. Over a great part of the cut, however, the breadth is said to be by no means in proportion to its depth, so that the sides are much too steep and are every now and again falling in.