As a volunteer, he worked on coastal cleanups and, with the guidance of prominent national environmentalist Lee Botts, organized and participated in public meetings for a stronger Great Lakes Water Quality Agreement between the U.S. and Canada.
From 1992 to 1998, he served as a litigating attorney with the National Wildlife Federation and Adjunct Clinical Assistant professor at the University of Michigan Law School in Ann Arbor.
Because of these and other efforts during his tenure, the Alliance for the Great Lakes also won the American Bar Association's Distinguished Award in Environmental Law & Policy, the first time for a public interest organization in the honor's history.
In his FY2010 budget, President Obama had established the Great Lakes Restoration Initiative to fund the work of 16 federal agencies within 11 Interagency Task Force departments.
Shortly after his appointment, Davis helped write the Action Plan guiding some $300 million per year under this presidential program to clean up Areas of Concern, prevent invasive species, restore habitat, reduce land-based pollution and ensure accountability.
[15] Also at this time, he helped establish the Asian Carp Regional Coordinating Committee to create a strategy[16] and guided the Initiative to fund work to address the imminent threat[17] of the fish showing signs of moving toward the Great Lakes.
[22] In 2012, he began working to build support within the Administration for another five years and, in March 2013, the White House announced its commitment, with Davis coordinating the effort to unify stakeholders around development of a new Action Pan.
[26] On January 21, 2018, Davis announced he was running for office, seeking the Democratic nomination for one of the nine commissioner positions at the Metropolitan Water Reclamation District of Greater Chicago in the March 20, 2018, primary.
Since joining the board, Davis has pushed to elevate environmental equity within the agency, led efforts to bring green infrastructure to suburban Cook County schoolyards, and insisted on the "polluter pays principle" for protecting public health from cancer-causing PFAS chemicals.