The broad valley of the Wallkill River nestles between the main Appalachian Mountains and the New York-New Jersey Highlands, supporting much local agriculture.

In the beginning of its course it drains the eastern section of Sussex County, New Jersey, then flows through the Wallkill River National Wildlife Refuge at the New Jersey/New York state line.

Other than the brief segment that follows the Orange-Ulster line, there is only southern Orange County, where it divides the towns of Minisink, Wawayanda and Wallkill on its west from Warwick and Goshen to the east.

[4] 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.

[4] In Ulster, vacationers frequented the Springtown neighborhood of New Paltz during the late 19th to early 20th century, making use of the Wallkill for recreation.

Many of the larger older homes still on Springtown Road were boarding houses for these people escaping from the summer heat to the cool banks of the Wallkill River.

While some focus on this Watershed was already occurring amongst government agencies, the WRTF created a non-governmental group that actively sought the volunteer participation of farmers, business people and other ‘ordinary’ citizens, in addition to government and conservation agency employees, to provide for broad-based leadership in protecting the Wallkill River and its watershed lands."

[8] In late summer 2016, the Wallkill River Watershed Alliance, along with Riverkeeper, documented a potentially toxic large blue-green algae bloom, prompting the two groups to warn that could be harmful to people, dogs or other pets.

[9] After the samples were taken from the River, New York's Department of Environmental Conservation confirmed a Harmful Algae bloom with High Levels of Toxins.