Native Americans knew the river as Twischsawkin. At least three prehistoric rock shelters have been found in archaeological digs in the region. For the indigenous peoples, it was not only important for its arable land but for its geological resources. The river and its valley are abundant in flint and chert, from which they made spear points and arrowheads.
European settlers of the region named it first the Palse River, after New Paltz. Later, when it was clear that the river continued well beyond the original New Paltz patent, it took after the Waal river in their nativeNetherlands. They worked their way down it from the Hudson Valley in the 17th century, and were followed by the British after the colony changed hands.
Settlers recognized the agricultural possibilities of the Drowned Lands almost as soon as they moved in. Efforts to divert the river and create more farmland appear to have begun as early as 1760. It would take 66 years, however, before a canal succeeded in draining the land and making enough available to profitably cultivate.
By that time industry was beginning to harness the river, too, as Jacob Walden established his mill in the village downriver that would later take his name. Millers in the Black Dirt Region clashed heavily with farmers in what were known as the Muskrat and Beaver Wars for decades afterwards, since the millers needed the water to flow freely while the farmers depended on keeping it diverted. In 1871 the farmers finally won. What industry there was would be confined to Montgomery and Walden where the railroad ran nearby.
In August 1955, the river experienced record-breaking flooding when hurricanes Connie and Dianebrought heavy rainfall to the region. Heavy flooding of the river and its smaller tributaries from the April 2007 nor’easter forced a number of road closures and evacuations of homes in its flood plain in central Orange County.