WET was founded in 1989 by a small group concerned about the county’s environmental policies (or lack thereof). During WET's first five years, its principal efforts were directed at public education about environmental issues.

In 2005, the Board of Directors secured IRS nonprofit status and focused on the rapidly increasing county sprawl development.

In 2011, water quality and the health of the Wicomico River and its watershed were added to WET’s mission. WET worked with the government and other NGOs to develop a watershed management plan for the Wicomico River. In 2016, WET stepped into the lead position of volunteer coordination, outreach, communication, and funding for the Wicomico Creekwatchers program.

In recent years, WET’s advocacy and policy has included active engagement with issues related to waste management, clean energy, clean water, wastewater treatment, public health risks, and environmental equity.