HIDALGO FALLS. The Hidalgo Falls are on the Brazos River five miles northwest of Washington-on-the-Brazos in Washington County (at 30°24' N, 96°11' W). The Hidalgo Cliffs rise above the falls, twenty feet above river level. They are surrounded by rolling hills that support post oak forest. The falls are a series of exposed limestone shoals that were formed by the erosion of the adjacent Hidalgo escarpment. They mark the dividing line between the middle and upper reaches of the Brazos River. Riverboats headed above Hidalgo Falls had to wait for a rise in the water level before proceeding upstream; if a boat's navigator misjudged the length of time the river would remain above normal level, the riverboat was trapped above the falls until the river rose again. The Brazos River above the falls offered limited access to upriver points during most of the year.
Pamela A. Puryear and Nath Winfield, Jr., Sandbars and Sternwheelers: Steam Navigation on the Brazos (College Station: Texas A&M University Press, 1976).