 The Mexicans would withdraw their water from the Rio Grande at the Acequia Madre about downstream from the point where the river starts to form the international border.The International Dam at the head of the Acequia Madre was completed in 1918, and improvements to the dam were completed in 1941.To ensure that they got their agreed share, in 1935 Congress authorized construction of the American Dam, 
which measures the Mexican portion before it reached the international border and lets it continue along the river to the International Dam, while diverting the rest along the new long American Canal to the Franklin Canal, used to irrigate the long El Paso valley.